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earthy quince [deleted]
7:27am, 13 July 2007
Well, Ultimate for me, anyway.
All future additional 285s I manage to snag from eBay to increase my lighting kit will be unhesitatingly modified to the same specs which I have learned through this process.
As an aspiring wedding photographer, I believe this will really give me the stats to mix with the big boys in terms of recycle speeds, battery pack longevity, yet with the added Strobist edge of traveling much lighter than big ol' mains-powered mono-lights.
Switcheroo

So, this is what started this whole monster-mod.
I was inspired by metropolicity and Ken Reppart's posts about custom Vari-power modules, one of which featured on the Strobist front page once.
Anyway, I simply started my investigative experiments by taking apart my own Vari-Power module and even though I have almost no electronics experience I quickly discovered that it was basically a switched series of resistors, with the auto range being a light-dependent-resistor.
So. Resistance at the Vari-Power socket determines the flash's power...
My first multi-meter and some twiddling with a couple of potentiometers later, I got me a table of values which basically told me that the less resistance, the less exposure.
I turned the flash over and over in my hands, mulling over where to put a set of sliding switches or something. Maybe the front? Where the Vari-Power module used to be?
Then it struck me. The exposure-assistant dial that I would never use even if I knew how to!
The picture tells the rest of the story, including my gory soldering skillz.
But that's a set of ten resistors plus open circuit which signals a full dump.
And I chose full-stop increments.
This gives me control right down to 1/1024th power!
Better than any stock unit I am aware of, and should suit all my needs from outdoor group photos to tiny macros without messing around with diffusers merely for the purpose of knocking down brightness.
Next step, mounting it inside the flash head. This was a really tight fit, but it does in fact fit.
It required breaking off the flyback transformer from the inside of the case, to which it is glued a short distance from the capacitor. A little ham-fisted, but mine was a used vintage and so the glue was pretty old and brittle anyway.
This left juuust enough space to jam the base of the switch in alongside the cap and transformer.
It is a really tight fit, and in fact is quite secure with a friction fit.
Then I routed the resistor-bundle across and out the hole already in the case for the existing cable. Soldered & plugged it into a blank space on the original board and all done.
I'm sorry I don't have photos of any of this. I promise I'll do a full set with the next unsuspecting 285 I nab off eBay.
Vivitar 285 Completed

All work completed, this is what my 285 now looks like.
As you can see, the useless exposure calculator on the side has been totally ripped out and replaced with the switch I made earlier.
A perfect fit, note that even the original indicator notch on the head of the flash is in the perfect position to serve me here.
This of course meant that the original Vari-Sensor module and it's associated socket was quite redundant. Again, I really got lucky here and got a really nice big rocker switch that was exactly the right size to mount in the hole left behind. This is the new power switch.
I think you'll agree it could easily pass for an original design without prior knowledge of what the flash actually looks like.
Finally, there's the outboard socket, which carries both power and synch. It's a microphone socket whose plug has a screw-on collar for a really nice, secure connection.
To elaborate: I knew I wanted to use an outboard SLA for power, so I got rid of the whole battery bay innards, leaving a nice big void inside the flash.
'Hmmm', thought I, 'that would be a very neat place to put the receiver trigger!'.
So I did.
But.
The flyback transformer is coaxial with the main capacitor, and just behind the base of the rotator switch. And it's a coil. Which means that it was causing interference with the receiver and causing the flash to trigger every time it topped off the charge in the capacitor.
Ugh. Tried shielding the transformer with aluminum-foil. No effect.
Tried shielding the receiver, but that of course stopped it from responding at all. Tried an extended antenna and the problem came back.
Blast.
Fine, so I can't put the receiver in the body of the flash. I ended up putting it in the Black Box (see that photo's description for more detail), and therefore needing a new pair of pins in my socket, hence the four you see here.
Now I just need some cosmetically convincing way to patch up or cover up the unused panel holes on the other two sides.
Black Box

So, this is the new power source for my Vivitar 285 (but it could be used for any strobe that uses 4AAs, since as you can see it's rated at 6 volts). Recycle times have been cut in half from even freshly topped-off NIMH AAs, which is a very nice improvement without seeming likely to allow me to meltdown the flash itself, particularly considering that the original design allowed an AC adaptor as an accessory.
Other modders may well recognize the green PCB near the socket. Yes, that is indeed the brains of a 16-channel eBay trigger.
It's been superglued at right-angles to a voltage stepdown module that throttles a parallel feed from the SLA to the 3-ish volts that the trigger would have expected from it's two AAAs.
I haven't yet the courage to see if more voltage would result in improved range, or just a dead component.
Observant Strobists might be wondering why the fifth pin on my DIN socket choice. Three reasons:
1) it was what was available to me (inexpensively - my blood is not rich enough to use XLRs) which provided a female. Putting male connections on a power supply is a big no-no.
2) All the sockets and plugs I have used (see also the corresponding details for the 285 mod) are typically used for purposes other than carrying power, so I hoped that if someone was crazy enough to go plugging their microphone or keyboard into random gear, the fact that this combination lead of five pins on one end and four on the other might ring the last alarm bell that this is a pretty weird custom jobbie.
3) the fifth pin goes to a fifth core in my wire, which forms an antenna extension the same height of my light stand and of course does not need to be connected on the other end.
No more silly comparisons with Pocket Wizards for me, no sir!
Wipes the floor with those overpriced monstrosities, with 100% trigger rates from a kilometer away when combined with my transmitter's antenna mod.
Finally, in the top-right of the photo, I used my Manfrotto quick-release shoes since I no longer need my tripod - at least not as much as I need my light!
With an appropriate combination of male/female parts for this and the flash itself, I can either mount this to the base cap of my light stand, or take the light stand out of the equation and just clip the flash directly to the top of it's Box (with an appropriate short cord) for floor-level lighting, or really tight quarters such as in a vehicle.
The weight of the SLA (just over a kilo) is a benefit in either case, providing a slight sandbagging effect if on the light stand, or being a secure anchor if it is the light stand.
All future additional 285s I manage to snag from eBay to increase my lighting kit will be unhesitatingly modified to the same specs which I have learned through this process.
As an aspiring wedding photographer, I believe this will really give me the stats to mix with the big boys in terms of recycle speeds, battery pack longevity, yet with the added Strobist edge of traveling much lighter than big ol' mains-powered mono-lights.
Switcheroo

So, this is what started this whole monster-mod.
I was inspired by metropolicity and Ken Reppart's posts about custom Vari-power modules, one of which featured on the Strobist front page once.
Anyway, I simply started my investigative experiments by taking apart my own Vari-Power module and even though I have almost no electronics experience I quickly discovered that it was basically a switched series of resistors, with the auto range being a light-dependent-resistor.
So. Resistance at the Vari-Power socket determines the flash's power...
My first multi-meter and some twiddling with a couple of potentiometers later, I got me a table of values which basically told me that the less resistance, the less exposure.
I turned the flash over and over in my hands, mulling over where to put a set of sliding switches or something. Maybe the front? Where the Vari-Power module used to be?
Then it struck me. The exposure-assistant dial that I would never use even if I knew how to!
The picture tells the rest of the story, including my gory soldering skillz.
But that's a set of ten resistors plus open circuit which signals a full dump.
And I chose full-stop increments.
This gives me control right down to 1/1024th power!
Better than any stock unit I am aware of, and should suit all my needs from outdoor group photos to tiny macros without messing around with diffusers merely for the purpose of knocking down brightness.
Next step, mounting it inside the flash head. This was a really tight fit, but it does in fact fit.
It required breaking off the flyback transformer from the inside of the case, to which it is glued a short distance from the capacitor. A little ham-fisted, but mine was a used vintage and so the glue was pretty old and brittle anyway.
This left juuust enough space to jam the base of the switch in alongside the cap and transformer.
It is a really tight fit, and in fact is quite secure with a friction fit.
Then I routed the resistor-bundle across and out the hole already in the case for the existing cable. Soldered & plugged it into a blank space on the original board and all done.
I'm sorry I don't have photos of any of this. I promise I'll do a full set with the next unsuspecting 285 I nab off eBay.
Vivitar 285 Completed

All work completed, this is what my 285 now looks like.
As you can see, the useless exposure calculator on the side has been totally ripped out and replaced with the switch I made earlier.
A perfect fit, note that even the original indicator notch on the head of the flash is in the perfect position to serve me here.
This of course meant that the original Vari-Sensor module and it's associated socket was quite redundant. Again, I really got lucky here and got a really nice big rocker switch that was exactly the right size to mount in the hole left behind. This is the new power switch.
I think you'll agree it could easily pass for an original design without prior knowledge of what the flash actually looks like.
Finally, there's the outboard socket, which carries both power and synch. It's a microphone socket whose plug has a screw-on collar for a really nice, secure connection.
To elaborate: I knew I wanted to use an outboard SLA for power, so I got rid of the whole battery bay innards, leaving a nice big void inside the flash.
'Hmmm', thought I, 'that would be a very neat place to put the receiver trigger!'.
So I did.
But.
The flyback transformer is coaxial with the main capacitor, and just behind the base of the rotator switch. And it's a coil. Which means that it was causing interference with the receiver and causing the flash to trigger every time it topped off the charge in the capacitor.
Ugh. Tried shielding the transformer with aluminum-foil. No effect.
Tried shielding the receiver, but that of course stopped it from responding at all. Tried an extended antenna and the problem came back.
Blast.
Fine, so I can't put the receiver in the body of the flash. I ended up putting it in the Black Box (see that photo's description for more detail), and therefore needing a new pair of pins in my socket, hence the four you see here.
Now I just need some cosmetically convincing way to patch up or cover up the unused panel holes on the other two sides.
Black Box

So, this is the new power source for my Vivitar 285 (but it could be used for any strobe that uses 4AAs, since as you can see it's rated at 6 volts). Recycle times have been cut in half from even freshly topped-off NIMH AAs, which is a very nice improvement without seeming likely to allow me to meltdown the flash itself, particularly considering that the original design allowed an AC adaptor as an accessory.
Other modders may well recognize the green PCB near the socket. Yes, that is indeed the brains of a 16-channel eBay trigger.
It's been superglued at right-angles to a voltage stepdown module that throttles a parallel feed from the SLA to the 3-ish volts that the trigger would have expected from it's two AAAs.
I haven't yet the courage to see if more voltage would result in improved range, or just a dead component.
Observant Strobists might be wondering why the fifth pin on my DIN socket choice. Three reasons:
1) it was what was available to me (inexpensively - my blood is not rich enough to use XLRs) which provided a female. Putting male connections on a power supply is a big no-no.
2) All the sockets and plugs I have used (see also the corresponding details for the 285 mod) are typically used for purposes other than carrying power, so I hoped that if someone was crazy enough to go plugging their microphone or keyboard into random gear, the fact that this combination lead of five pins on one end and four on the other might ring the last alarm bell that this is a pretty weird custom jobbie.
3) the fifth pin goes to a fifth core in my wire, which forms an antenna extension the same height of my light stand and of course does not need to be connected on the other end.
No more silly comparisons with Pocket Wizards for me, no sir!
Wipes the floor with those overpriced monstrosities, with 100% trigger rates from a kilometer away when combined with my transmitter's antenna mod.
Finally, in the top-right of the photo, I used my Manfrotto quick-release shoes since I no longer need my tripod - at least not as much as I need my light!
With an appropriate combination of male/female parts for this and the flash itself, I can either mount this to the base cap of my light stand, or take the light stand out of the equation and just clip the flash directly to the top of it's Box (with an appropriate short cord) for floor-level lighting, or really tight quarters such as in a vehicle.
The weight of the SLA (just over a kilo) is a benefit in either case, providing a slight sandbagging effect if on the light stand, or being a secure anchor if it is the light stand.
cankleswebb
16 years ago
wow, looks like the ultimate 285!
i'm most impressed by the hidden sync, could you post a how to for an antenna on the receiver? i tried, i started by cutting the bar (paperclip sized) assuming it was the aerial, and what i got was a dead unit.
i'm most impressed by the hidden sync, could you post a how to for an antenna on the receiver? i tried, i started by cutting the bar (paperclip sized) assuming it was the aerial, and what i got was a dead unit.
earthy quince [deleted]
16 years ago
I will do a full set of (properly lit) photos with the next one I mod in the same manner, but I certainly feel your pain. I killed two of my slaves monkeying with the antenna.
In the end, for this particular one, I just suppose I got lucky because for a start I didn't make any permanent changes.
All I did was twist a little wire around the middle of the bar, at a point where it shouldn't come into contact with any other components or traces on the PCB, then held it in place with a little solder.
At least then if I totally messed it up, I could de-solder it and undo the changes. Hopefully.
I should also say that I've modded the antenna on my transmitter, so it could very well be that it only happens by chance that the two modified antennas are working together on some resonant frequency via their interacting lengths.
I don't feel brave enough to go snipping off antenna lengths to explore this possibility.
In the end, for this particular one, I just suppose I got lucky because for a start I didn't make any permanent changes.
All I did was twist a little wire around the middle of the bar, at a point where it shouldn't come into contact with any other components or traces on the PCB, then held it in place with a little solder.
At least then if I totally messed it up, I could de-solder it and undo the changes. Hopefully.
I should also say that I've modded the antenna on my transmitter, so it could very well be that it only happens by chance that the two modified antennas are working together on some resonant frequency via their interacting lengths.
I don't feel brave enough to go snipping off antenna lengths to explore this possibility.
FlashZebra
Posted 16 years ago. Edited by FlashZebra (member) 16 years ago
But, you need a dial that goes to 11.
So, it will play louder than those that go to 10.
Enjoy! Lon
So, it will play louder than those that go to 10.
Enjoy! Lon
earthy quince [deleted]
16 years ago
Heheh, yeah. Actually, the underlying rotary switch has up to twelve positions, so I briefly did consider having some hidden position, but (1) I couldn't come up with anything useful to have for that function and (2) I wanted to make it easy for any future Voice Activated Lightstands to use.
masontrullinger
16 years ago
This is by far the most professional-looking set of flash mods I've seen. Any idea on how much it cost in parts and also how many hours you spent on this? Al Jacobs sells similar black box SLAs for around $100. He doesn't hard wire anything to flashes and suggest people get the quantum cables or make dummy batteries attached to a cable and a DIN plug that attaches to his black box. I have one and it works amazingly well but I think I want to try making a couple more for my other flashes. Your idea to incorporate the trigger into the power supply is awesome.
Thanks,
Mason Trullinger
www.photogels.com
Thanks,
Mason Trullinger
www.photogels.com
vamseekoneru
16 years ago
"I have almost no electronics experience"
Right.
I must admit you had me at the '1/1024th power'.. here I was already having visions of modding mine..
But then, at "The flyback transformer is coaxial with the main capacitor...", you lost me. It's all English to me :)
Seriously though. Super mod. It looks really professional. I think I'm going to try modding my own. At least the vari-power switch part. One day.. *sigh*
Right.
I must admit you had me at the '1/1024th power'.. here I was already having visions of modding mine..
But then, at "The flyback transformer is coaxial with the main capacitor...", you lost me. It's all English to me :)
Seriously though. Super mod. It looks really professional. I think I'm going to try modding my own. At least the vari-power switch part. One day.. *sigh*
andyptak
16 years ago
Although you say that you don't know a lot about this subject, you use words that I don't even know the meaning of!
I nominate you for the Nobel Prize for your superhuman effort here. Well done. how long did it take you?
I nominate you for the Nobel Prize for your superhuman effort here. Well done. how long did it take you?
Austin M. Shaffer
16 years ago
damn. ever since i worked in camera repair, i've always wanted to start modding the faults/drawbacks of flash units (also design/build guitar amplifiers/cabinets). this is exactly the kind of thing i wanted to start doing!!
i'm proud of ya!
i'm proud of ya!
earthy quince [deleted]
Posted 16 years ago. Edited by earthy quince (member) 16 years ago
Thank you all very much for the nice feedback.
Vamsee.K
andyptak
It's true! Most of the electronics tools I used, I bought and was taught how to use for this project!
I guess I just had some very good friends helping me, and also chalk it up to all those formative years of playing with Lego!
Maybe I should do a more detailed and independent follow up with my next light, because this was actually three projects in one post - could be confusing.
1) The better light output control
2) Move and improve the power source
3) Integrate the slave trigger
So in fact the ability to control the light down ten stops is quite a separate issue from the one about the parts of the flash causing RF interference with the trigger.
In short, don't get scared off of trying this yourself by my brain-dump of verbal diarrhea!
Standard Warning & Disclaimer
What you should be scared of, though, is the lethal voltage levels that can be present in a flash's innards, specifically that dirty great grey cylinder-o-death otherwise known as the 350volt, 1100uF capacitor.
If that bastard is holding a full charge, then it'll just be a waiting bear trap for something to short it's contacts.
If it's your finger, it'll burn a hole right through, nevermind grabbing one terminal in each hand, thereby making your heart part of the circuit.
So, watch yourself. Charging the flash, firing a full dump, and then immediately switching it off should help a little, but yeah.
Just be careful!
masontrullinger
Very well spotted! Note my photo's caption - I was inspired by Al Jacob's work.
His is more upmarket, such as a nice metal case and so on, but the basic concept of using an SLA was a great help to point me in the right direction.
Anyway, that's a very good question. Hmm, let's total it up:
SLA Battery Charger, $25
SLA Battery, $13
Plastic Enclosure, $4
Voltage Regulator Kit, $6
Manfrotto Quick Release, $50
Heatshrink, $1
Spool of Wiring, $5
DIN Plug (x2), $6
DIN Socket, $1
MIC Plug, $2
MIC Socket, $2
PCB Header Pin Pairs (x4), $4
Rocker Switch, $3
Rotator Switch, $3
Bunch-o-Resistors, $1
eBay Slave Trigger, $20
Which is a total of around AU$150, allowing for wastage and learning losses.
Note that the most expensive parts, the Charger and Quick Release are single-purchase and what I already had lying around, respectively.
To build another, it would be more like AU$100, or US$80-ish.
As you can see, that's a pretty worthwhile saving over Al's Black Box, which is twice as much, plus shipping, which brings to mind the fact that the L in SLA ain't there for decoration...
But, this reckons without the component of time spent, which is a point which has been brought up in the various eBay trigger threads.
If you're a high-level pro photographer, ponying up for PocketWizards and doing an hour-long shoot may be less of a money loss than going GadgetInfinity and spending a few hours soldering.
Similar caveat applies here.
Me, I'm not worth that much per-hour, so I am happy to pocket the change and learn a lot.
Given that the Strobist way involves Scavenged Black Drinking Straws, Cereal Box Cardboard, and quote "Tupperware and Trash Bags", plus of course the fact of all of your interest in my post, I suspect we're in good company here!
As to how much time I spent... that's hard to pin down, because I had a lot of stops-and-starts when I came up against an unexpected problem, or needed to consult someone for advice, nevermind the times I had to back up and redo something a few steps back.
To build one again from scratch, now that I know what I'm doing and have all correct tools at the ready? Hmm, I think I'll say it'd take about... 4 or 5 hours? I'll have a much better idea next time around.
It's true! Most of the electronics tools I used, I bought and was taught how to use for this project!
I guess I just had some very good friends helping me, and also chalk it up to all those formative years of playing with Lego!
Maybe I should do a more detailed and independent follow up with my next light, because this was actually three projects in one post - could be confusing.
1) The better light output control
2) Move and improve the power source
3) Integrate the slave trigger
So in fact the ability to control the light down ten stops is quite a separate issue from the one about the parts of the flash causing RF interference with the trigger.
In short, don't get scared off of trying this yourself by my brain-dump of verbal diarrhea!
Standard Warning & Disclaimer
What you should be scared of, though, is the lethal voltage levels that can be present in a flash's innards, specifically that dirty great grey cylinder-o-death otherwise known as the 350volt, 1100uF capacitor.
If that bastard is holding a full charge, then it'll just be a waiting bear trap for something to short it's contacts.
If it's your finger, it'll burn a hole right through, nevermind grabbing one terminal in each hand, thereby making your heart part of the circuit.
So, watch yourself. Charging the flash, firing a full dump, and then immediately switching it off should help a little, but yeah.
Just be careful!
Very well spotted! Note my photo's caption - I was inspired by Al Jacob's work.
His is more upmarket, such as a nice metal case and so on, but the basic concept of using an SLA was a great help to point me in the right direction.
Anyway, that's a very good question. Hmm, let's total it up:
SLA Battery Charger, $25
SLA Battery, $13
Plastic Enclosure, $4
Voltage Regulator Kit, $6
Manfrotto Quick Release, $50
Heatshrink, $1
Spool of Wiring, $5
DIN Plug (x2), $6
DIN Socket, $1
MIC Plug, $2
MIC Socket, $2
PCB Header Pin Pairs (x4), $4
Rocker Switch, $3
Rotator Switch, $3
Bunch-o-Resistors, $1
eBay Slave Trigger, $20
Which is a total of around AU$150, allowing for wastage and learning losses.
Note that the most expensive parts, the Charger and Quick Release are single-purchase and what I already had lying around, respectively.
To build another, it would be more like AU$100, or US$80-ish.
As you can see, that's a pretty worthwhile saving over Al's Black Box, which is twice as much, plus shipping, which brings to mind the fact that the L in SLA ain't there for decoration...
But, this reckons without the component of time spent, which is a point which has been brought up in the various eBay trigger threads.
If you're a high-level pro photographer, ponying up for PocketWizards and doing an hour-long shoot may be less of a money loss than going GadgetInfinity and spending a few hours soldering.
Similar caveat applies here.
Me, I'm not worth that much per-hour, so I am happy to pocket the change and learn a lot.
Given that the Strobist way involves Scavenged Black Drinking Straws, Cereal Box Cardboard, and quote "Tupperware and Trash Bags", plus of course the fact of all of your interest in my post, I suspect we're in good company here!
As to how much time I spent... that's hard to pin down, because I had a lot of stops-and-starts when I came up against an unexpected problem, or needed to consult someone for advice, nevermind the times I had to back up and redo something a few steps back.
To build one again from scratch, now that I know what I'm doing and have all correct tools at the ready? Hmm, I think I'll say it'd take about... 4 or 5 hours? I'll have a much better idea next time around.
jerrykids
16 years ago
man that vivitar has been pimped. i envy your acomplishment.
can you upload mp3's in there too?
can you upload mp3's in there too?
luxuriant party [deleted]
16 years ago
very nicely done!
I actually can't believe that I stumbled across this, because I'm in the process of doing something very similar - I've already got a functioning prototype super-285HV with an integrated ebay reciever (V2)... and I'm in the process of doing something similar to what you've done with the vari-power module. I'll post pics when it's done.
[techy mumbo-jumbo follows]
By the way - are you sure that the misfire was due to interference and not your power supply? I rewired the existing power switch with a couple of resistors to provide 3V power for the receiver - I had the same constant misfires until I put a capacitor right where the battery used to be... I guess that prevented spikes in the voltage, which led to no more misfires.
...I guess this is what happens when you're an engineer by day :-)
I actually can't believe that I stumbled across this, because I'm in the process of doing something very similar - I've already got a functioning prototype super-285HV with an integrated ebay reciever (V2)... and I'm in the process of doing something similar to what you've done with the vari-power module. I'll post pics when it's done.
[techy mumbo-jumbo follows]
By the way - are you sure that the misfire was due to interference and not your power supply? I rewired the existing power switch with a couple of resistors to provide 3V power for the receiver - I had the same constant misfires until I put a capacitor right where the battery used to be... I guess that prevented spikes in the voltage, which led to no more misfires.
...I guess this is what happens when you're an engineer by day :-)
earthy quince [deleted]
16 years ago
It couldn't have been the power supply because at that prototype stage, I just shoved the whole receiver into the body of the flash, so it was still running off its batteries as usual. Yes, they were freshly charged.
Makes no nevermind to me, though. I got my extra range out of that long cord, so all's well.
On the topic of power supplies, though, I tried to figure out the high-voltage connector, but got stumped. What do you think: would using a 12volt SLA instead of 6volt kill it, or boost it?
Makes no nevermind to me, though. I got my extra range out of that long cord, so all's well.
On the topic of power supplies, though, I tried to figure out the high-voltage connector, but got stumped. What do you think: would using a 12volt SLA instead of 6volt kill it, or boost it?
o7photographs
16 years ago
Hey Jonathan,
Can you give some details on the voltage regulator you used? I have been thinking about this for some time but haven't been near a decent electronics shop lately :(
thanks,
Richard
Can you give some details on the voltage regulator you used? I have been thinking about this for some time but haven't been near a decent electronics shop lately :(
thanks,
Richard
Zacker The One and Only
16 years ago
wow.. can ya put an Ipod Mini in there too?
lol nice job, makes me want one... why? idunno... cause its cooool!
lol nice job, makes me want one... why? idunno... cause its cooool!
luxuriant party [deleted]
16 years ago
I can't say I'm particularly interested in the HV connector and/or an SLA setup - light weight and portability are more important to me than recharge speed and capacity... so I'm afraid I can't help much with those suggestions. My initial thought is not to try the 12V thing unless you can find someone else who has done it - even if you could get it to work, the recharge would probably be so fast that you'd constantly be on the edge (or past it!) of burning up the flash... then again, maybe your next mod could be a liquid-cooled flash bulb :-)
Just one thing I'm wondering now is why you did the switches/resistors, rather than just throwing in a potentiometer(?) The only advantage I could see would be if you calibrated the individual resistors to each increment by 1/3 f-stop - or whatever (which, incidentally, would be extremely slick!).
Just one thing I'm wondering now is why you did the switches/resistors, rather than just throwing in a potentiometer(?) The only advantage I could see would be if you calibrated the individual resistors to each increment by 1/3 f-stop - or whatever (which, incidentally, would be extremely slick!).
earthy quince [deleted]
Posted 16 years ago. Edited by earthy quince (member) 16 years ago
Wow! Thank you for more of the kind words, and call me a pencil necked nerd if ya like (like there's any other evidence of that needed), but I'm quite over the moon with this post hitting the big time, getting a nod of approval from the chief Strobist himself...
For the regulator: I was getting a bit more than 6 volts from the SLA, at full charge.
More like 6.6v, which was enough to make me play cautious with my last functional GI slave and get a variable regulator as opposed to a straight 3v.
As to the various suggestions of mass-production: No, thanks!
I did this project to get a kit that fitted my needs and wants, and then get back out there.
In fact, the most common thought I had during this process was "I can't wait 'til this is finished".
Al Jacobs' Black Box has already been mentioned.
Go to his page, and the first thing he says is that he is doing this only since retiring from photography.
As I mentioned in my original report (it's a bit long to be just a post, isn't it?), I specifically wanted ease-of-use. This definitely did not mean trying to precision-twiddle a free-range dial when the light could be near ceiling height.
So, while I did use a pot' or two during my investigation and prototyping stage. I chose a positive, locked set of values for my final unit.
Interesting you should mention the 1/3rd stop thing, though.
In using a ten-way switch, I of course had to choose my increment.
I first thought "half-stops", but that only took me half-a-stop less than 1/16 power - no real improvement over the original Vari-power module, and well behind the versatility of today's manufacturer-dedicated TTL units, which usually go down to at least 1/64th, often 1/128th.
So I solved the problem and leapfrogged the competition by using full-stop increments, giving me control down to 1/1024th, as roddymac22 recognised.
Taking David's horse-shoes-and-hand-grenades line of reasoning fully to heart, I figured that any situation where I wanted - or needed - fractional-stop accuracy in my light ratios (since overall exposure can be controlled to the third-stop via aperture), setup time would plenty to allow moving of lights back-and-forth.
There is in fact a big void in the flash now where the old battery bay was.
A Nano could fit in there.
Heck, I could fit a Shuffle and mount a simple speaker.
As to why...
Maybe I could use that to amuse my hapless subjects as I moved the lights around?
Audio confirmation of my lights' settings and firings?
I would draw the line at my lights talking back to me when I positioned them poorly...
"Hey, I can't see the subject's face anymore!"
"That's because I umbrella'd you"
"An umbrella?! Come on! Hard light is better. I can be more efficient..."
"Quiet, you. I'm trying to think"
"Softie!"
"That's it! You wanna be dramatic? Fine, let's see how you like a full-straw snoot!"
"MMMmmmph! mbflbblfbblphhhh!"
o7photographs
16 years ago
Hey Jonathan,
You did put the 6.6 volts directly on the flash?
As I think of it, it isn't that much since with 4 alkalines you'd get 6v, the flash should be able to handle that .6 extra...
Richard
--------------------------------------
urban-exploring.com
strobist gel packs available!
You did put the 6.6 volts directly on the flash?
As I think of it, it isn't that much since with 4 alkalines you'd get 6v, the flash should be able to handle that .6 extra...
Richard
--------------------------------------
urban-exploring.com
strobist gel packs available!
roddymac22
16 years ago
"That's it! You wanna be dramatic? Fine, let's see how you like a full-straw snoot!"
"MMMmmmph! mbflbblfbblphhhh!"
LOL!
"MMMmmmph! mbflbblfbblphhhh!"
LOL!
luxuriant party [deleted]
16 years ago
Wow - so you actually selected resistors to correspond to each range? I'm most impressed! (unless it's a linear relationship, in which case, I'm only slightly less impressed, and might do the same on mine). Would you care to share the resistor values you used (assuming it doesn't involve peeling the heat-shrinkable tubing)?
PS: 1/1025, ie: 10 stops is quite impressive. I just measured mine yesterday and the minimum power I could get was just a smidgen under 9 stops lower than firing full tilt. Maybe I need a large gauge of wire to get that last stop :-)
thanks again for sharing all this info!
PS: 1/1025, ie: 10 stops is quite impressive. I just measured mine yesterday and the minimum power I could get was just a smidgen under 9 stops lower than firing full tilt. Maybe I need a large gauge of wire to get that last stop :-)
thanks again for sharing all this info!
grave.robbers
16 years ago
That warning about not touching the cap's contacts is one that should be strongly heeded.
I recently pulled apart my old digital point-and-shoot, to see if i could take it's flash unit off camera. Boy, did I get the shock of my life when I accidently touched the cap's contacts. It didn't burn my finger, but it hurt like hell, and scared the living daylights out of me.
I recently pulled apart my old digital point-and-shoot, to see if i could take it's flash unit off camera. Boy, did I get the shock of my life when I accidently touched the cap's contacts. It didn't burn my finger, but it hurt like hell, and scared the living daylights out of me.
infxualbydesign
16 years ago
If you are keen to mod a flash then do so expecting to get a zap. its not just the cap terminals either, in old flashes with slightly dodgy wiring any metal part could potentially be the conductor i found out the hard way with two of my flashes ( yes twice bitten)
once the mods are done though, the pain fades away into variable lighting bliss
once the mods are done though, the pain fades away into variable lighting bliss
Jano Myburgh
16 years ago
Very, VERY cool mod. I too would like to know what the resistor values were between stops & wehter it was a linear relationship. Thanks for putting this up.
earthy quince [deleted]
Posted 16 years ago. Edited by earthy quince (member) 16 years ago
Hey all. This is a follow-up since quite a few would like to know the final resistor values I used to control the 285's output.
To restate again, there's a pretty good chance that these particular values are specific to the 285, and potentially my individual unit.
Having said that, it's reasonable to assume that all such "auto-thyristor", "auto-eye" or other auto flashes of this era which are not TTL rely on a Light-Dependant-Resistor to work their magic, which is what we are playing off here.
It's therefore conceveable that only a handful of LDRs were commonly used for such purposes.
So. This is a guide only.
I strongly recommend using a couple of variable-resistance potentiometers to do exploratory exposures and nail down the exact values for your flash, especially of course if you don't want to use the same full-stop increments I did.
Final note is that these values were in some cases dictated by what fixed-value resistors were available.
For example, the actual 1/4-power resistance was 50k exactly, but funnily enough no such metal-film resistor is available.
Oh well.
These were all close enough. Which is probably why no one makes the other values.
Talk about circular reasoning.
100k
51k
27k
16k
11k
6.8k
4.3k
3k
2k
1k
I didn't have a 1k pot' to go lower than this with any kind of accuracy or ease, and I got all the values I needed so I stopped.
However, there is still more room for control.
Bridging the contacts, and therefore presenting pretty much zero resistance, did in fact produce a very, very low output which I didn't measure but looked quite a few stops down again.
Anyway, I hope this was a help even with all my long-winded ramblings. Thanks for the feedback and questions. Keep 'em coming!
To restate again, there's a pretty good chance that these particular values are specific to the 285, and potentially my individual unit.
Having said that, it's reasonable to assume that all such "auto-thyristor", "auto-eye" or other auto flashes of this era which are not TTL rely on a Light-Dependant-Resistor to work their magic, which is what we are playing off here.
It's therefore conceveable that only a handful of LDRs were commonly used for such purposes.
So. This is a guide only.
I strongly recommend using a couple of variable-resistance potentiometers to do exploratory exposures and nail down the exact values for your flash, especially of course if you don't want to use the same full-stop increments I did.
Final note is that these values were in some cases dictated by what fixed-value resistors were available.
For example, the actual 1/4-power resistance was 50k exactly, but funnily enough no such metal-film resistor is available.
Oh well.
These were all close enough. Which is probably why no one makes the other values.
Talk about circular reasoning.
100k
51k
27k
16k
11k
6.8k
4.3k
3k
2k
1k
I didn't have a 1k pot' to go lower than this with any kind of accuracy or ease, and I got all the values I needed so I stopped.
However, there is still more room for control.
Bridging the contacts, and therefore presenting pretty much zero resistance, did in fact produce a very, very low output which I didn't measure but looked quite a few stops down again.
Anyway, I hope this was a help even with all my long-winded ramblings. Thanks for the feedback and questions. Keep 'em coming!
luxuriant party [deleted]
16 years ago
thanks!
By the way, you were asking about the HV connector: I've taken a look at it, and as I understand the circuit (caveat: I'm a mechanical engineer, not electrical), the HV terminals can take a 300V input - either AC or DC. It seems to be pretty much a direct feed to the capacitor, and I'm guessing that the Vivitar AC adapter just has a transformer that brings the 115V AC current up to ~300V. So to answer your question, I think that connecting a 12V supply to the HV leads wouldn't do much. Again, I'm not certain about this, and wouldn't recommend that you try - just sharing my interpretation of the circuit.
Note for anybody reading above, who isn't already scared by the voltages invovled: do not try messing with this. 300V - especially when connected to a capacitor - is not something to mess around with unless you've *completely* confident in your abilities.
Also note that, even with the batteries disconnected, parts of the circuit board are connected to the flash capacitor. I really can't overemphasize the potential danger of fiddling with one of these units if you don't know what you're doing.
By the way, you were asking about the HV connector: I've taken a look at it, and as I understand the circuit (caveat: I'm a mechanical engineer, not electrical), the HV terminals can take a 300V input - either AC or DC. It seems to be pretty much a direct feed to the capacitor, and I'm guessing that the Vivitar AC adapter just has a transformer that brings the 115V AC current up to ~300V. So to answer your question, I think that connecting a 12V supply to the HV leads wouldn't do much. Again, I'm not certain about this, and wouldn't recommend that you try - just sharing my interpretation of the circuit.
Note for anybody reading above, who isn't already scared by the voltages invovled: do not try messing with this. 300V - especially when connected to a capacitor - is not something to mess around with unless you've *completely* confident in your abilities.
Also note that, even with the batteries disconnected, parts of the circuit board are connected to the flash capacitor. I really can't overemphasize the potential danger of fiddling with one of these units if you don't know what you're doing.
Entropy512
16 years ago
NICE mod!
Since starting to read Strobist (and ordering one of MPEX's SN1 kits this morning), I've been wondering about the feasibility of a remote trigger that had built-in remote power adjustment. (something which I have seen numerous people comment that they would love to have). The problem was that there would be no way to do remote power adjustment without cooperation from the flash. This mod reveals just how one would do such a thing. If a microcontroller could somehow switch those resistors in and out, you would then have a microcontroller-controlled flash output power.
A Gumstix Verdex XM4 is $130, the breakout board is $27.50. There should be some reasonably priced off-the-shelf low-latency wireless systems that would be able to support triggering and remote adjustment (plus a ton of other functions - even an Atmel AVR would be more than sufficient for remote power adjustment if you could solve the communications issue. The Gumstix would be massive overkill for anything but some sort of TTL variant.)
Since starting to read Strobist (and ordering one of MPEX's SN1 kits this morning), I've been wondering about the feasibility of a remote trigger that had built-in remote power adjustment. (something which I have seen numerous people comment that they would love to have). The problem was that there would be no way to do remote power adjustment without cooperation from the flash. This mod reveals just how one would do such a thing. If a microcontroller could somehow switch those resistors in and out, you would then have a microcontroller-controlled flash output power.
A Gumstix Verdex XM4 is $130, the breakout board is $27.50. There should be some reasonably priced off-the-shelf low-latency wireless systems that would be able to support triggering and remote adjustment (plus a ton of other functions - even an Atmel AVR would be more than sufficient for remote power adjustment if you could solve the communications issue. The Gumstix would be massive overkill for anything but some sort of TTL variant.)
Sean Phillips
16 years ago
Although I have no real intention of doing this mod, it is very cool and it got me thinking...
Why not put the power controller switch in the black box instead of in the flash. That way it is always at ground level where you are instead of up at 10 feet on a light stand. You can't run this thing without the black box anyway, so you should be able to have the brains and controls whereever you want them.
Just a thought.
Why not put the power controller switch in the black box instead of in the flash. That way it is always at ground level where you are instead of up at 10 feet on a light stand. You can't run this thing without the black box anyway, so you should be able to have the brains and controls whereever you want them.
Just a thought.
fir3bird
16 years ago
I wonder what the flash duration would be at 1/1024 power. That might make good flash for stopping bullets in flight. But at 1/1024 power it would have to be mighty close to the flight path.
luxuriant party [deleted]
16 years ago
Hey, congrats - you made it to the front page of strobist!
I've been going nuts lately trying to get the 10 stops of control that you've got, only to realize just now that you're using a 285, whereas I'm working with the newer 285HV - which I can only seem to get a range of 8 stops out of (minimum of ~1/256). I guess they don't make them like they used to!
I've been going nuts lately trying to get the 10 stops of control that you've got, only to realize just now that you're using a 285, whereas I'm working with the newer 285HV - which I can only seem to get a range of 8 stops out of (minimum of ~1/256). I guess they don't make them like they used to!
joneikifi
16 years ago
I noticed that there is no mention of a fuse in the circuit. I would recommend adding one near one of the battery leads. Otherwise a short circuit somewhere could start a fire.
MichaelBass
16 years ago
From one who loves to take things apart (and usually get them back together), AWESOME mod!
As a possible next generation prototype, if you were trying to get multiple ranges, you could add either a multiposition DIP switch (or another rotary selector switch) tied to different resistors prior to the input of your existing rotary switch. It would take some re-figuring of the current set of values, but this is how many timers get many different ranges, by having one controller act as the multiplier for the second controller.
Michael
www.MichaelBassDesigns.com
As a possible next generation prototype, if you were trying to get multiple ranges, you could add either a multiposition DIP switch (or another rotary selector switch) tied to different resistors prior to the input of your existing rotary switch. It would take some re-figuring of the current set of values, but this is how many timers get many different ranges, by having one controller act as the multiplier for the second controller.
Michael
www.MichaelBassDesigns.com
Tom Legrady
16 years ago
So you've improved the re-charge time by going with the SLA batteries, and you've extended the power control way beyond the original 1/16.
But I do wonder if you really need 1/1024. And you have unused space left over. If you add an extra capacitor in parallel with the original one, you'll double the power output, or go with three extra capacitors instead of just one extra for two stops extra light. Then instead of full power -> 1/1024, you get full * 4 -> 1/256, or full - 2 f- stops -> full + 8 f-stops. ( or the other way around, depending how you visualize incemental f-stops.
But I do wonder if you really need 1/1024. And you have unused space left over. If you add an extra capacitor in parallel with the original one, you'll double the power output, or go with three extra capacitors instead of just one extra for two stops extra light. Then instead of full power -> 1/1024, you get full * 4 -> 1/256, or full - 2 f- stops -> full + 8 f-stops. ( or the other way around, depending how you visualize incemental f-stops.
tim-j
Posted 16 years ago. Edited by tim-j (member) 16 years ago
@Tom:double the power output, or go with three extra capacitors instead of just one
But would the tube handle it over a long period?
But would the tube handle it over a long period?
Sean McCormack
16 years ago
I've spent hours searching through both metal and plastic project boxes in Maplin to suit their 6V SLA battery that I've used for my flash power. Nothing even remotely the same size. I may need to buy a bigger one and hacksaw it, issue being keeping it straight!
I was planning on putting the trigger circuit inside the battery compartment, so I'm glad to have read this and saved myself the bother!
I was planning on putting the trigger circuit inside the battery compartment, so I'm glad to have read this and saved myself the bother!
Nick Devenish
16 years ago
RE: The Capacitor.
If you have taken the batteries out, you could drain the capacitor by either carefully (i.e. without touching any metal contacts at all - plastic tongs or pliers I guess) connect a resistor between the two terminals to drain it slowly - if I remember my EE correctly, connecting a 2k resistor would take about 10 seconds to drain to 1% power, with a draw of 150ma through it. (4k 20s at 75ma you get the idea).
Otherwise, you could connect the two terminals of the capacitor directly to each other to short it, but I wouldn't like to make any comments on the safety of this to you or your capacitor - but at least the capacitor would be safely drained.
Oh, and testing that the voltage level across the capacitor is zero is a good way of testing it too - I think most flashes auto-discharge when turned off anyway.
If you have taken the batteries out, you could drain the capacitor by either carefully (i.e. without touching any metal contacts at all - plastic tongs or pliers I guess) connect a resistor between the two terminals to drain it slowly - if I remember my EE correctly, connecting a 2k resistor would take about 10 seconds to drain to 1% power, with a draw of 150ma through it. (4k 20s at 75ma you get the idea).
Otherwise, you could connect the two terminals of the capacitor directly to each other to short it, but I wouldn't like to make any comments on the safety of this to you or your capacitor - but at least the capacitor would be safely drained.
Oh, and testing that the voltage level across the capacitor is zero is a good way of testing it too - I think most flashes auto-discharge when turned off anyway.
davidh4976
16 years ago
I'm working on a mod to my 30-year old (original owner) 285 so I can have a better jack for the sync cord. I know you can use the red and black wire that go to the foot, but does anyone know what the green and white wires (that go to the foot) are for? They go to the thyrister...
BTW, nice mod!
BTW, nice mod!
FlashZebra
Posted 16 years ago. Edited by FlashZebra (member) 16 years ago
davidh4976,
The green and white wires go to the Vivitar sync port already in the flash foot.
As an aside, why are you adding a sync port, that Vivitar sync port that the green and white wires go to typically works fine. It is a reliable sync port if you get a good quality cord.
Enjoy! Lon
The green and white wires go to the Vivitar sync port already in the flash foot.
As an aside, why are you adding a sync port, that Vivitar sync port that the green and white wires go to typically works fine. It is a reliable sync port if you get a good quality cord.
Enjoy! Lon
davidh4976
Posted 16 years ago. Edited by davidh4976 (member) 16 years ago
I've used the Vivitar sync port and cord, but it doesn't seem to be a good fit.
I've managed to put a Radio Shack phono jack (#274-346) in the case (back side immediately next to the red/green ready light) and expect to get a good, consistent fit with that with a custom cable I'll make.. I can easily connect the phono jack to the red/black wires that go from the foot to the PCB board inside the flash. What has me puzzled is, why does the sync port use the green/white that go to the thyrister instead of the same red/black wires? Does the green/white have some other function?
I've managed to put a Radio Shack phono jack (#274-346) in the case (back side immediately next to the red/green ready light) and expect to get a good, consistent fit with that with a custom cable I'll make.. I can easily connect the phono jack to the red/black wires that go from the foot to the PCB board inside the flash. What has me puzzled is, why does the sync port use the green/white that go to the thyrister instead of the same red/black wires? Does the green/white have some other function?
FlashZebra
Posted 16 years ago. Edited by FlashZebra (member) 16 years ago
davidh4976,
The Vivitar plug fit seems vague, but it typically functions perfectly (with a good cord). This is a case where the perception of the fit is inconsistent with the actual performance of the fit.
Did you actually have misfires using the Vivitar connector, or are you just concerned about misfires based on your impression of the fit of the connector?
I think the hotshoe contacts and the Vivitar port contact are isolated from each other.
I think this isolation is accomplished by a mechanical switch that is connected to the Vivitar sync port. I speculate that when you push in a Vivitar connector, it activates a switch mechanism that activates the Vivitar sync port and isolates the hotshoe.
Enjoy! Lon
The Vivitar plug fit seems vague, but it typically functions perfectly (with a good cord). This is a case where the perception of the fit is inconsistent with the actual performance of the fit.
Did you actually have misfires using the Vivitar connector, or are you just concerned about misfires based on your impression of the fit of the connector?
I think the hotshoe contacts and the Vivitar port contact are isolated from each other.
I think this isolation is accomplished by a mechanical switch that is connected to the Vivitar sync port. I speculate that when you push in a Vivitar connector, it activates a switch mechanism that activates the Vivitar sync port and isolates the hotshoe.
Enjoy! Lon
earthy quince [deleted]
16 years ago
Wow, some serious activity on this thread!
And I actually made it to the front page! I am humbled.
So, anyway, there are some questions outstanding which I need to reply to, but I have been concentrating on my L102 submission.
Which I have finally turned in. Whew.
I kinda stink next to the other finals, but that is hopefully because I have procrastinated.
I guess I want to say thanks for all the interest, and I have acquired a second 285, mwahahah!
So, as promised, I shall more fully document the process with decently-lit photos of every step.
Replies to questions:
Jason Joseph Photography
Quite a few people have asked for me to do this to their flash.
I really doubt that it would be worthwhile for me to make the black box section of this mod for other people because someone else already does it much better than I likely could - Al Jacobs, who was recently linked to on the Strobist front page.
The second type is a 'maybe', and that is in the case of just wanting the 10-position output dial on the side.
This could conceivably be worthwhile even after various to-and-fro shipping costs were considered.
But, really. I wouldn't want to.
My reason is quite simple: I would rather get shooting with my gear than soldering more stuff for others.
Tell y'all what: If it gets to the end of L102 and I still totally stink, then I will hang up my camera in defeat, and take all incoming orders for modded 285s that come my way!
ssphillips
Putting the output control in the black box is a pretty interesting idea!
Unfortunately, I look at what I had to work with and what I had available and I realise this would have taken a lot more work and in fact I have no particular combination of components at my local parts store to run such an additional pair of wires down my cable-run.
At least, not in a way that satisfies me.
Thinking further...
Working with the flash in real-world usage, I have found that most of the time I am manipulating parts of the whole light-stand-flash-battery setup mostly around where the flash itself is.
Adjusting angle...applying gels or snoots...adjusting stand height... all of these are usually done while standing or at most bending over.
To have to squat down to ground level every time I wanted to change power is not quite a worthwhile trade-off for what I believe will be a relative minority of occasions where ceiling-height power adjustments might be an annoyance, and even if they were I may still have to fiddle around 'up there' anyway, with the aforementioned other lighting controls.
So, on second thoughts, I'm pretty happy with the setup as-is.
And I actually made it to the front page! I am humbled.
So, anyway, there are some questions outstanding which I need to reply to, but I have been concentrating on my L102 submission.
Which I have finally turned in. Whew.
I kinda stink next to the other finals, but that is hopefully because I have procrastinated.
I guess I want to say thanks for all the interest, and I have acquired a second 285, mwahahah!
So, as promised, I shall more fully document the process with decently-lit photos of every step.
Replies to questions:
Quite a few people have asked for me to do this to their flash.
I really doubt that it would be worthwhile for me to make the black box section of this mod for other people because someone else already does it much better than I likely could - Al Jacobs, who was recently linked to on the Strobist front page.
The second type is a 'maybe', and that is in the case of just wanting the 10-position output dial on the side.
This could conceivably be worthwhile even after various to-and-fro shipping costs were considered.
But, really. I wouldn't want to.
My reason is quite simple: I would rather get shooting with my gear than soldering more stuff for others.
Tell y'all what: If it gets to the end of L102 and I still totally stink, then I will hang up my camera in defeat, and take all incoming orders for modded 285s that come my way!
Putting the output control in the black box is a pretty interesting idea!
Unfortunately, I look at what I had to work with and what I had available and I realise this would have taken a lot more work and in fact I have no particular combination of components at my local parts store to run such an additional pair of wires down my cable-run.
At least, not in a way that satisfies me.
Thinking further...
Working with the flash in real-world usage, I have found that most of the time I am manipulating parts of the whole light-stand-flash-battery setup mostly around where the flash itself is.
Adjusting angle...applying gels or snoots...adjusting stand height... all of these are usually done while standing or at most bending over.
To have to squat down to ground level every time I wanted to change power is not quite a worthwhile trade-off for what I believe will be a relative minority of occasions where ceiling-height power adjustments might be an annoyance, and even if they were I may still have to fiddle around 'up there' anyway, with the aforementioned other lighting controls.
So, on second thoughts, I'm pretty happy with the setup as-is.
davidh4976
Posted 16 years ago. Edited by davidh4976 (member) 16 years ago
Anyone know where I can get a replacement screw for attaching the foot to a 285?
By the way, I figured out what the green and white wires are for. I was able to get a wiring diagram and determined that, in a stock configuration:
a. when you insert the sync cord into the hot shoe, it disconnects the hot shoe's normal contacts so you can only use the sync cord.
b. if you use the sensor extension cord to extend the sensor from the front of the flash, it has a hot shoe on it too and that also has a sync port.
c. the green/white wires extend the hot shoe disconnect function to the extended hot shoe.
If you never use the sensor extension cable, you don't need the green/white wires.
If you don't ever use the sensor extension cord, the green and white wires never come into play and are not needed.
By the way, I figured out what the green and white wires are for. I was able to get a wiring diagram and determined that, in a stock configuration:
a. when you insert the sync cord into the hot shoe, it disconnects the hot shoe's normal contacts so you can only use the sync cord.
b. if you use the sensor extension cord to extend the sensor from the front of the flash, it has a hot shoe on it too and that also has a sync port.
c. the green/white wires extend the hot shoe disconnect function to the extended hot shoe.
If you never use the sensor extension cable, you don't need the green/white wires.
If you don't ever use the sensor extension cord, the green and white wires never come into play and are not needed.
ben plattes
16 years ago
Thinking of doing this to two of my HV's, but I can't figure out what resistor corresponds to what power rating.
Also, where did you source your parts? I have a place lined up online, but I was wondering if there was some place better.
Thanks!
Also, where did you source your parts? I have a place lined up online, but I was wondering if there was some place better.
Thanks!
ben plattes
16 years ago
Inside the vari-power module, the resistors are
nothing (duh): 1/1
180k: 1/2
82k: 1/4
24k: 1/16
nothing (duh): 1/1
180k: 1/2
82k: 1/4
24k: 1/16
NabityPhotos
16 years ago
@davidh: how would the green and white wires be connected if you do use the sensor extension cord? I am replacing a broken foot on my Viv285HV.
Thanks.
- Ron
Thanks.
- Ron
NabityPhotos
16 years ago
I replaced my Vivitar 285HV foot tonight and figured out the wiring.
Initially, I had read that the red wire goes to the center pin and the black wire goes to the base, and the white and green wires are left unattached. With this arrangement however, the extension cord does not fire the flash, as pointed out by davidh4976 above.
The solution is to solder the red and white wires together to the center pin, and the black wire to the base. Just clip and set aside the green wire. I tested this out with a circuit tester first, then tested it again after I hooked it all up.
Initially, I had read that the red wire goes to the center pin and the black wire goes to the base, and the white and green wires are left unattached. With this arrangement however, the extension cord does not fire the flash, as pointed out by davidh4976 above.
The solution is to solder the red and white wires together to the center pin, and the black wire to the base. Just clip and set aside the green wire. I tested this out with a circuit tester first, then tested it again after I hooked it all up.
NabityPhotos
16 years ago
@mtreinik: haha - that was about it. I was half expecting my wife to sneak up behind me with the proverbial paper bag full of air and pop it..
aback expert [deleted]
16 years ago
here's what i envision as an ultimate power-supply/sync/output-adjustment product, that would require no mods on the part of the end user, just plug-and-play:
basically the same kind of "black box" that we have here, with the big battery, inert hotshoe mount, and radio trigger inside, but also with the output-adjust knob on the top face (or elsewhere).
then, a coiled cable (like a phone cord or some of the paramount cables), long enough for the box to sit on the ground/weight a stand and still reach to the flash when the stand is fully extended.
one end of the cable plugs into the black box: on the other end it splits into three leads: one that plugs into the socket for the vari-power unit (for output adjustment), one with a dummy battery pack that plugs into the battery bay in the flash (to power the flash), and one with a vivitar or PC plug (for sync). you could also include a shorty lead for when you're mounting the flash right on the box.
the connector on the black box would obviously have to be a multi-prong deal, i'm not sure what's out there that would work... there has to be something though. perhaps an old printer-cable plug or something? everything else seems fairly straightforward, at least no more complicated than what's been done here already.
this would give you all the benefits seen in this mod without any technical prowess needed of the end user and allow output adjustment without having to collapse and re-set-up the stand.
basically the same kind of "black box" that we have here, with the big battery, inert hotshoe mount, and radio trigger inside, but also with the output-adjust knob on the top face (or elsewhere).
then, a coiled cable (like a phone cord or some of the paramount cables), long enough for the box to sit on the ground/weight a stand and still reach to the flash when the stand is fully extended.
one end of the cable plugs into the black box: on the other end it splits into three leads: one that plugs into the socket for the vari-power unit (for output adjustment), one with a dummy battery pack that plugs into the battery bay in the flash (to power the flash), and one with a vivitar or PC plug (for sync). you could also include a shorty lead for when you're mounting the flash right on the box.
the connector on the black box would obviously have to be a multi-prong deal, i'm not sure what's out there that would work... there has to be something though. perhaps an old printer-cable plug or something? everything else seems fairly straightforward, at least no more complicated than what's been done here already.
this would give you all the benefits seen in this mod without any technical prowess needed of the end user and allow output adjustment without having to collapse and re-set-up the stand.
ben plattes
Posted 16 years ago. Edited by ben plattes (member) 16 years ago
for heavy duty stuff, xlr or neutrik microphone cables rule.
Robertv! (Edinburgh, UK)
16 years ago
I'd also use XLR cables, but watch out for the current required by the flash. A standard mic lead will struggle. If you do decide to go this way, try to get a "QUAD" cable. Not the maker, the type, it has 4 cores and a screen. Double up the wires as required. They're usually the same size as the 2 core ones and have less filler material. Also try to get a nice flexible neoprene lead.
If possible, try to use an unusual XLR too. I don't want your powerpack plugged into my desk or microphone accidentally. A 4 pin one would be a good bet.
If possible, try to use an unusual XLR too. I don't want your powerpack plugged into my desk or microphone accidentally. A 4 pin one would be a good bet.
ben plattes
16 years ago
just finished my version of this mod. it's awesome so far. will post a complete review when i'm done with the second one (one down, one to go...)
markjlinton
16 years ago
Does the use of resistors lock you into those specific settings on the output, wouldn't a good variable resistor give lots more flexibility with a simpler circuit to build?
Crantastic
16 years ago
The power values are not linear. The variable resistor will be linear. Meaning full power is at 12oclock, 1/2 is at 6oclock, 1/4 is at 9oclock and the rest all bunched up between 9 and 12 oclock.
Ramūnas
16 years ago
jonathankauphotography: could you take a pic of the flash igniting/disconnecting part of the board? its right next to the flash itself , I need to know the values of the resistors on it.
klevkoff
15 years ago
I am planning to try a few interesting mods to a 285 (haven't yet), but figured I'd add a few comments to the ongoing mods discussion (if anybody's still listening :)).
1) I don't have a schematic of the 285, but, in most of the thyristor control circuit schematics I've seen, the controlling resistors are passing pretty fast signals - so the inductance of the resistors may matter. Not that anything bad would happen - just that different types of resistors may give you slightly different results, so make the measurements with the type of resistors you plan to actually use before soldering anything permanently, or at least check. (Specifically, an inductive resistor might slow the signal down enough to prevent you from getting accurate short/low-power settings.)
2) Someone mentioned the possibility of putting the control into the battery box - with a direct wire. Same suggestion - perform final tests and calibration through the wire you plan to use - the capacitance of a long wire may also affect the exact results you get from each resistor.
3) Variable resistors (pots) aren't all linear - an "audio taper" or "log" one will provide (like it says) a non-linear resistance. Note that, unlike linear ones, they have a "low end" and a "high end" (with an audio taper, half resistance is at about 10 o'clock). They also make audio taper pots with a built in mechanical power switch - with separate terminals (remember the radios that click off when you turn them all the way down), which could be used to provide a dead short for shortest time or to provide a power-off click. Also remember that, if you use a variable, the power it can stand is proportional - if it's set at 1/2, then it can only stand 1/2 of full rated power (although I don't think it matters for this situation, not a bad idea to make sure it doesn't smoke at some particular setting though).
1) I don't have a schematic of the 285, but, in most of the thyristor control circuit schematics I've seen, the controlling resistors are passing pretty fast signals - so the inductance of the resistors may matter. Not that anything bad would happen - just that different types of resistors may give you slightly different results, so make the measurements with the type of resistors you plan to actually use before soldering anything permanently, or at least check. (Specifically, an inductive resistor might slow the signal down enough to prevent you from getting accurate short/low-power settings.)
2) Someone mentioned the possibility of putting the control into the battery box - with a direct wire. Same suggestion - perform final tests and calibration through the wire you plan to use - the capacitance of a long wire may also affect the exact results you get from each resistor.
3) Variable resistors (pots) aren't all linear - an "audio taper" or "log" one will provide (like it says) a non-linear resistance. Note that, unlike linear ones, they have a "low end" and a "high end" (with an audio taper, half resistance is at about 10 o'clock). They also make audio taper pots with a built in mechanical power switch - with separate terminals (remember the radios that click off when you turn them all the way down), which could be used to provide a dead short for shortest time or to provide a power-off click. Also remember that, if you use a variable, the power it can stand is proportional - if it's set at 1/2, then it can only stand 1/2 of full rated power (although I don't think it matters for this situation, not a bad idea to make sure it doesn't smoke at some particular setting though).
klevkoff
15 years ago
A few WARNINGS as well:
1) If they are connecting 300v directly to the capacitor through that HV input, it could be dangerous to just connect any old 300v supply. There could be specific requirements vis-a-vis current limiting and such, and you could well blow something up if you exceed them - on the flash or on your power supply. (The flash capacitor does get stressed, and heat up, from being rapidly discharged when you flash it - which is unavoidable. Recharging it super-fast from a massive supply will stress it further and make it heat up sooner or may even damage it.)
2) If the capacitor is connected directly to the connector, then the voltage on the capacitor is ON THE PIN of the connector. That would make that connector very dangerous to poke around in. (It would be NICE if they blocked it with a diode, but don't count on it.)
3) Fully discharging the flash by flashing it does NOT entirely drain the capacitor - only down to 50v or so. Even worse, some flash caps have a habit of "recovering" some of their charge over several minutes - even after you short them directly for a few seconds (some power is stored in the electrolyte like a battery). To be entirely safe, you should make up a discharge resistor with clip leads and leave it across the capacitor when you're playing nearby. IF that HV connector IS directly connected to the capacitor, a connector wired with a resistor on the right pins would be a handy way to do this.
1) If they are connecting 300v directly to the capacitor through that HV input, it could be dangerous to just connect any old 300v supply. There could be specific requirements vis-a-vis current limiting and such, and you could well blow something up if you exceed them - on the flash or on your power supply. (The flash capacitor does get stressed, and heat up, from being rapidly discharged when you flash it - which is unavoidable. Recharging it super-fast from a massive supply will stress it further and make it heat up sooner or may even damage it.)
2) If the capacitor is connected directly to the connector, then the voltage on the capacitor is ON THE PIN of the connector. That would make that connector very dangerous to poke around in. (It would be NICE if they blocked it with a diode, but don't count on it.)
3) Fully discharging the flash by flashing it does NOT entirely drain the capacitor - only down to 50v or so. Even worse, some flash caps have a habit of "recovering" some of their charge over several minutes - even after you short them directly for a few seconds (some power is stored in the electrolyte like a battery). To be entirely safe, you should make up a discharge resistor with clip leads and leave it across the capacitor when you're playing nearby. IF that HV connector IS directly connected to the capacitor, a connector wired with a resistor on the right pins would be a handy way to do this.
Chilin.Tran
15 years ago
in the midst of doing this mod and benjamin david plattes' mod.... radio shack only carries the a 6 step rotary switch. does anyone know where i can find a 10/12 step rotary switch? also, the different resistors, does anyone know where i can by an assorted pack of these or do i have to buy sets of 4-5 of them each at .99 a pop?
lastly, if anyone has done this mod or has these parts, i'd love to buy them off of you. please email me at chilintran@gmail.com thanks for the help!
lastly, if anyone has done this mod or has these parts, i'd love to buy them off of you. please email me at chilintran@gmail.com thanks for the help!
ruori
14 years ago
I found that my 285 has stopped working after several years of non-use. That is, the charging light does not come on even with fresh batteries, while the battery contacts appear as shiny as new. So, having done some soldering in my time, I thought I'd open up the thing and see whether I could spot something obviously wrong.
But I couldn't. That is, open it up. I unscrewed the four screws on the front of the unit, but nothing came loose. Can anyone help? I would hate to break the plastic parts. This is the flash I sort of grew up with.
But I couldn't. That is, open it up. I unscrewed the four screws on the front of the unit, but nothing came loose. Can anyone help? I would hate to break the plastic parts. This is the flash I sort of grew up with.
W.G.W.
14 years ago
you need to pry off the silver disc opposite the exposure calculator. Under the disc is a metal clip that holds the front and back together.
ruori
14 years ago
Thank you, W.G.W. Looking at the silver disc, I found a fifth screw (much shorter than the previous four.) However, unscrewing it did not have any effect. So, how does one "pry off" the disc? There does not seem to be anything to grip it by, say. It seems to be held in place by a kind of (black plastic) collar or ring.
Roger Krueger
14 years ago
Thoughts from 283, not 285 experience, but maybe relevant:
Old 283s with the round 2SB627 chopper transistor fry instantly on 12v (and they fry shorted, which is especially dramatic). The later ones with the rectangular-case chopper survive, but the poor thing sounded so frantic I never went beyond a first test.
Part of why I killed the 12v experiment is because it dawned on me that I was now delivering twice the voltage off the step-up transformer. If the circuit that shuts off charging when the target cap voltage is reached were to fail (and I've had a Sunpak do exactly that) it'd at least try to take the poor cap all the way to 700v, likely with ugly results.
Double caps are hard on the tubes, I figured about 1000 full-double-power pops per tube. But changing tubes on a 283 is trivial, never had a 285 apart; I'd assume the zoom head makes tube access harder.
Old 283s with the round 2SB627 chopper transistor fry instantly on 12v (and they fry shorted, which is especially dramatic). The later ones with the rectangular-case chopper survive, but the poor thing sounded so frantic I never went beyond a first test.
Part of why I killed the 12v experiment is because it dawned on me that I was now delivering twice the voltage off the step-up transformer. If the circuit that shuts off charging when the target cap voltage is reached were to fail (and I've had a Sunpak do exactly that) it'd at least try to take the poor cap all the way to 700v, likely with ugly results.
Double caps are hard on the tubes, I figured about 1000 full-double-power pops per tube. But changing tubes on a 283 is trivial, never had a 285 apart; I'd assume the zoom head makes tube access harder.
Eugeniu
12 years ago
how would i go about adding a optical slave onboard ( 3.5mm jack )
do i connect it to the red / black wires off the hot shoe ?
or can i put it elsewhere ... i have those peanut style optical slaves with 3.5mm mono jack
do i connect it to the red / black wires off the hot shoe ?
or can i put it elsewhere ... i have those peanut style optical slaves with 3.5mm mono jack
