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Gadget Infinity trigger internals

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Entropy512 says:

Since my day job is as an RF engineer and there's already a small mod community centered around the Gadget Infinity trigger system, I decided to pop open my GI transmitter and take some macro shots.

Here is a picture of both the top and bottom of the circuit board:



If you look at the part number on the board, it is labeled "FS-616", which I believe is the part number of the 16-channel studio trigger. Note that there are two unconnected positions for switches on each side of the channel selection DIPs. Can anyone who owns a combo of 16-ch and 4-ch equipment try seeing if they can trigger their 16-ch equipment with a 4-ch? It looks like the 4 channels of the 4-ch version are a subset of the 16, and the transmitters actually use the exact same circuit board.

As to how to remove the circuit board - Even though it looks like the header connecting it to the shoe PCB is a disconnectable header, I was only able to remove it by desoldering it. This was extremely difficult to do, even after removing as much solder as I could I had difficulty removing the board, and nearly destroyed the pads for the shoe connection in the process.

As to how the circuit works:
Acccording to http://blog.savel.org/2007/02/01/car-mp3-player/, the AM81SA10705 is some sort of shift register IC. I can't find ANY information on this chip whatsoever in any place I have looked. It appears to take the four bits from the channel selector and clock them out onto the pin in the upper left corner. The remainder of the circuitry APPEARs to be a simple CW oscillator with the frequency set by a 433 MHz resonator. This circuit seems to be keyed off and on by the output of the IC. I cannot figure out what clocks the IC itself. If I could find ANY information on it or a datasheet that would be much easier.

Unfortunately some of the components in the oscillator/transmitter circuit are not labeled what they are and none have values so it's difficult to figure out the exact design of the circuit, otherwise it would likely be easy to do all sorts of nifty modifications.

Another observation: If I'm interpreting this circuit correctly, the "channel" selection does not actually change the frequency, but changes the on/off sequence of the transmission. In short, this thing transmits a 4-bit number to the receiver, and if that number matches the receiver's DIP switch settings the receiver will trigger. In the case of the 4-channel triggers, two of the four bits appear to be floating high (i.e. set to 1.) regardless of DIP settings. Unfortunately while I have access to test equipment that could confirm this interpretation, I'm not able to use it for personal purposes. :(

If one wanted to improve the sync speed of this system they would have to figure out how the IC clocks out its data and increase this rate. The lack of any external clocking circuitry means that battery voltage may very likely have some effect, so I can see why the "replace the battery marked as for testing purposes only" supposedly improves sync speed.

A picture of my closeup (not macro yet, extension tubes are on the way!) setup can be found at http://andydodd.smugmug.com/gallery/3227400/1/180167059

More info: I pulled out my ohmmeter. The part labeled "N1" is one of the two white SMT parts, both of which appear to be RF-blocking inductive chokes. It appears they wanted seperate chokes for both the oscillator power supply and the power amplifier output.

C3 is a DC-blocking capacitor for the antenna.

The part labeled "273" is a 27k ohm resistor which does not have a label on the silkscreen. It appears to be a bias resistor for TR2, which is likely a bipolar transistor with the bias current and oscillator/resonator output connected to its base. (i.e. TR2 is the output amplifier of the transmitter.)

TR1 basically turns on the transmitter by providing it with a ground connection.

Edit: thonord posted a link to the datasheets for the big can over at www.flickr.com/groups/strobist/discuss/72157601512667943/ - As I suspected, it's a SAW resonator (a variant of a frequency crystal) and the circuitry near it on the board forms a basic RF oscillator.

I may try to create a schematic for the transmitter this weekend, unfortunately some component values (such as the inductors) are still unkown.
Originally posted at 8:51PM, 3 August 2007 PDT (permalink)
Entropy512 edited this topic 81 months ago.

Swordfish7 [deleted] says:

Man i wish i was better at electronics, i have been working on making a high speed flash trigger for way to long now..
thanks for the info btw
82 months ago (permalink)

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SoulJah says:

So...

Are they worth what they're charging us?

In anycase, which hole exactly do I solder a new antenna on to? I had an idea after fiddling with my USB wifi antenna. The length is about right to match the 433mhz frequency it's transmitting, around 4+ inches (4 inches + whatever lenght the trace is on the board).

I purchased a Mini PCI to RP-SMA male to mate it with my existing antenna later on. Advisable? Do I just connect the middle connector to the board? Would both be ok?
82 months ago (permalink)

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Entropy512 says:

Optimally - if you look on that picture, the hole in the bottom left corner, but you will have to cut the trace along the left edge. (Although many people have done fine without cutting the trace.)

Many people solder to the upper left hole instead, making the addon antenna an extension of the original one. While this can extend the antenna to a quarter wave, a 1/4 wave antenna with a 90 degree bend in the middle will behave differently (and not as well) as a straight one. Still it will be a significant improvement over the normal configuration.

I'd say they're worth what they're charging us, since they're charging us hardly anything. :) I couldn't possibly build one myself for the price they charge.

For the best results with a detachable antenna, you would need to properly ground the outer shield. In this case, there is an easily accessible ground point close to the upper left solder hole on the antenna - the upper four solder points of the DIP switches are grounded, and on this particular unit the leftmost of those is unpopulated.

Does anyone have both 4-channel and 16-channel units? Can you test to see if a 16-channel with all four switches works with a 4-channel with both switches off? (Note, the "on" label on the switches has been described as occasionally incorrect by some people, don't trust it.)
82 months ago (permalink)

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Mozella says:

>>........Souljah Pro User says:

So...

Are they worth what they're charging us?..<<

I'd say they're a bargain at twice the price.

I charge more to take a PICTURE of this device than what the Chinese vendors charge to send the device to me from half way around the world. LOL

Bob

Bob
82 months ago (permalink)

Brian2550 [deleted] says:

RF-04 & RF-616 Transmitters both fire the PT-04 & RD616 recivers
82 months ago (permalink)

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Entropy512 says:

OK cool, good to confirm my suspicions, and useful to know when shopping in the future. :)
82 months ago (permalink)

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kenkyee says:

Entropy: the V1 4-channel hotshoe triggers are compatible w/ the V1 16-channel 1/4" photo plug triggers. It's the usual 2-bit vs. 4-bit encoding (it was documented in one of the discussions at one point).

They supposedly changed the V2 trigger/receiver encoding (so they claim) so V1 and V2 are no longer compatible. I'm surprised Brian2550 got them to work because PT-04 is V2 and RF-04 is V1 (I think).
82 months ago (permalink)

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SoulJah says:

V1s trigger the V2's Channel 1. That's why I set mine to Channel 4, dip switch to O and N.
82 months ago (permalink)

Brian2550 [deleted] says:

Cactus V2 PT04 Are not compatible with PT04 or RF616receivers
82 months ago (permalink)

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ChatSauvage says:

When receiving the wrong items I tested to see if the 4ch would fire the 16ch with no luck. I think I had them both set to O & N, with the other 2 switches left in the 0 position (assuming that O, N & the other 2 switches in the same position are the 1's)
82 months ago (permalink)

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Entropy512 says:

If you look at the circuit board, the 4-channel version has the switches attached to the middle two pairs of pads. i.e. the 2 switches of the 4-channel version are the equivalent to the middle two switches of a 16-ch version.

So both the first and last switch of a 16-ch unit must both be off, and the middle two should match the settings of the 4-ch.
82 months ago (permalink)

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J0hno says:

I thought of analysing these devices before... but haven't gotten around to it because they just work fine for me.

To me, it makes sense that the mystery chip is a shift register with a serial output on pin 14. It should be easy enough to tell what it is doing by connecting a scope up to the baseband output - or even the RF output seeing as its only 433MHz.

Looking at the layout, I'd agree that its most likely binary amplitude shift keying, with a couple of start bits and then the 4 bits from the DIP switches in sequence

Has anyone done any comparison between the V1 and V2 models in terms of circuit design?
82 months ago (permalink)

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Entropy512 says:

I wish I had an oscilloscope for personal use. :) There's no way I'd be able to use one of the units at work for this kind of thing.

Being able to see the receiver board design would make things easier, but until I get additional receivers (I'll be ordering a 16-ch set soon most likely) I don't want to risk killing my current receiver. (It appears there is no way to remove the board and look at the bottom without desoldering all of the sync connectors.)

The more I think about it, the more likely this IC is some sort of UART with an internal clock. I agree that it is SOME sort of parallel-to-serial interface with the output on pin 14, what I can't figure out is where the clock signal is! :)
82 months ago (permalink)

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darren.whitley says:

Did you happen to go to the company website that is listed on the board?

www.yh21cn.com/English/Index.asp
82 months ago (permalink)

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J0hno says:

If I get the time, I'll measure the output out of mine tomorrow. It would be interesting to see just what it is.

Regarding the website - have you found anything useful there? On a related note, I wonder why people keep calling them "gadget infinity" triggers. Its no secret they are are YinHe brand triggers - because it is printed all over the box packaging they come in - or if you buy them through gadget infinity do they replace that with their own packaging?
82 months ago (permalink)

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the one and only roly says:

Johno the reason why people keep referring to them as the "gadget infinity" triggers is because this is the handle of one of the people who is selling them on ebay and by the looks of it is shifting large volumes of the stuff.

Maybe we should write to them and ask if they want to make a donation to strobist for all the business that is being sent to them :)
82 months ago (permalink)

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SoulJah says:

We buy it off of Gadgetinfinity.com. Cheaper shipping.
82 months ago (permalink)

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makelessnoise says:

I've seen conflicting advice around adding to the antenna on these. The conflicts I wonder about are two-fold:

1) What length of wire should be used? I've read that the ideal is a 6.6 inch antenna for a 433MHz signal. Since there's 1.25" strip in the board, I add a 5.35 inch length of wire (6.6 - 1.25 = 5.35) to do this properly.

2) To which hole should the length of wire be soldered? In the photo at the top of this thread, it is the hole at the top left, or the hole near the bottom left? Does it matter?

I did it this way. Do I need to change it?
Gadget Infinity Mod
Originally posted 78 months ago. (permalink)
makelessnoise edited this topic 78 months ago.

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jeffegg2 says:

I have both the original 4 channel transmitter / receiver, and the new V2s transmitter / receivers and even when set to the same channel, are not compatable. perhaps they changed the clock speed of the shift register? it could be that this freq was being interfeared with by the Vivitar285hv?
78 months ago (permalink)

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texas_bae says:

@makelessnoise- Using the picture at the very top of this thread as the reference, as you have previously, the end of the antenna on the pcb is top left. So, to achieve the 6.6 inch total length, you should have added your 5.35 inches to the end, or top left, opposite of what you did. Does it matter? While your antenna is not "optimal", I'd be willing to bet you have significantly improved it's performance already. The choice to change it is really up to you. Since you have already made the hole in the cover, you could either unsolder from your current postion, and solder the same wire to the other side, uncoil a couple of coils to reach the antenna cover/hole/thingy, and your done. Or, alternatively, you could unsolder, replace wire with 6.?? inch wire, resolder, and cut the trace on the PCB. The latter seems a little more drastic and if you not comfortable cutting the trace on the pcb, you might avoid this.
Originally posted 78 months ago. (permalink)
texas_bae edited this topic 78 months ago.

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makelessnoise says:

Yeah, I don't think I'll be cutting that trace. I'm trying to leave my mods largely "undoable" so I can remove all the mods and still have the original functionality...aside from a few holes, that is. Ha ha. The resoldering idea is a good idea. I'll try that. Oh, and you're right. I did see a huge range boost with the one mod.
78 months ago (permalink)

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Crantastic says:

Entropy: I've got access to some some antenna cores and winding wire and can build a fullwave antenna. What do I need to consider before making the antenna. (like if the impedance will smoke the transmitter)
78 months ago (permalink)

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monpunx says:

so what would cause the continues popping of the receiver?
78 months ago (permalink)

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Sim911 says:

@monpunx

Well as far as I understand the 433mhz frequency that these operate on is a common freq. for a lot of other things around the house. I have read that using some foil around them helps, but of course you cannot cover the receivers antenna. I am going to try and shield mine in the next couple days and post (if it works).
78 months ago (permalink)

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monpunx says:

@Sim911,

thanks for this, please do update this thread with the result, I'm still not satisfied somehow, that this would solve the continues popping. but I have to try it as well, and see for myself
78 months ago (permalink)

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fredsoo says:

I have both the 4ch and 16 ch units (V1 on the 4ch).

The 4 ch unit can trigger the 16 ch receiver.
The channels are arranged like this:

0110 = 11,
0100 = 10,
0010 = 01,
0000 = 00.

The outer switches (1 and 4) should always be off, and then the inner two correspond to the two switches on the 4channel version.

Has anybody checked with the V2s whether something similar is going on between V1 and V2? The dips could be just inverted, or maybe they forced the V2s to have dips 1 and 4 high (a configuration that can't be had by the V1s. If somebody has both V2s and 16ch receivers, it wouldn't be hard to find out.
Originally posted 78 months ago. (permalink)
fredsoo edited this topic 78 months ago.

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George Natis says:

@Entropy
nice research

Now if you could encounter the arising problem with any antenna extension (esp. Kuster) regarding the cmos banding symptoms on the 5D... :)
78 months ago (permalink)

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texas_bae says:

So I just picked up two used 16-channel sets. I have a V2 set. From what I've read, I've seen that the V1 and 16-channel sets are usable together. But not the V1 and V2. So, does this imply that the V2 and 16-channel won't work together?

Sorry if this is already covered elsewhere.
77 months ago (permalink)

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tarjei99 says:

AM81SA10705 chip found with google www.chipdocs.com/pndecoder/datasheets/WJ/SA1070.html
77 months ago (permalink)

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Tobe Whysoserious says:

makelessnoise:
Just to throw something in regarding the antenna length: the wavelength for 433mhz comes to
300/433=0.6928 meters, which is about 27.3 inch

this would make a quarter WL of 6.82 inch.

I'm not a signal technician, so I can't judge how much difference the additional 0.2 inch make.

www.csgnetwork.com/freqwavelengthcalc.html

Edit:
OK i've added a 1/8th WL 8.5cm 3.4in cable and seperated the internal antenna. The range is now approx. 20meters (5 story building)
www.flickr.com/photos/tobemayr/2102076378/
Originally posted 77 months ago. (permalink)
Tobe Whysoserious edited this topic 77 months ago.

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o7photographs says:

Anyone with better electronic skills dare to say somehting about using the recievers with a higher voltage?

tx, Richard

---
www.urban-exploring.com
77 months ago (permalink)

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aparatgraf says:

The chip is definitely not the TDMA PA SA1070. Judging from the dimensions and pictures the SA1070 is the size of a desk telephone. We certainly can't afford a GaAS amplifier like that.

I have no issue hijacking one of the scopes for this. I guess the first part would be to get a pinout for the parts, then figuring out what to probe.
77 months ago (permalink)

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gazpix says:

Anyone noticed sync speed droppingafter modding?
I did the 7 " wire in the top left hole and snipped backgradually til range increased method ...
much more reliable but now noticed not syncing above 1/30 sec. new batteries or old

Any thoughts
76 months ago (permalink)

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gazpix says:

Anyone ?
76 months ago (permalink)

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gordolake says:

What about the receiver antenna, any mods worth considering there?

@o7photographs "Anyone with better electronic skills dare to say somehting about using the recievers with a higher voltage?"

I'd suggest trying higher voltage on the transmitter rather than the receiver.


Steve
76 months ago (permalink)

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chris pants says:

i added an antenna, and lost a lot of range and reliability. does anyone have any ideas (other than, just take it off)? it's the kuster mod found here: jeremykuster.blogspot.com/2007/10/gi-cactus-v2s-modificat...
76 months ago (permalink)

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Steve M Smith says:

I have a transmitter and two receivers. One receiver works fine, the other has a range of just a few feet.

Even temporarily holding a 1/4 jack plug (without cable) onto the antenna track, effectively adding about 2", increased the range substantially.

I will be making a permanent modification today.

It is my opinion that just about any increase in length of the antenna will give a good increase in range (unless, possibly, you make it too long).

Considering the cost of these items, this is not a criticism of the original design of incorporating the antenna into the PCB, just an improvement.
72 months ago (permalink)

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mic.mark says:

Regarding shielding the receiver to cure constant popping - is there an easier way to do this?

My knowledge around the subject of RF is hazy. At best. But - would a microwave stop any stray RF from telephones, light switches, wifi etc? Just connect the flash to the receiver and pop the whole lot in the microwave. DO NOT TURN ON!

The shielding on the outside of the microwave should stop most RF, right? Or is it designed to stop only certain frequencies?
Either way, it won't hurt to try.
72 months ago (permalink)

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tschnitzlein says:

mic.mark, What are you trying to achieve? A microwave oven, when powered down is nothing else than a Faraday's cage - it shields electromagnetic fields irrespective of frequency. Radiation from inside doesn't get out, but radiation from outside doesn't get in either. If you put the receiver inside a microwave, it won't receive any signal - not even the signal you want it to receive.

Instead, constant receiver popping points to RF oversensitivity and/or poor antenna matching, or to some serious manufacturing defect. Or, I would suggest searching for sources of stray radiation in the vicinity of the receiver.

E.g. does the receiver still pop if the transmitter is switched off? Is a computer in the vicinity? Do you have some other remote controllers operating on RF in the neighborhood (think garage openers)? Is there an HAM radio amateur in your neighborhood? Is there someone using a walkie-talkie etc. ...
Originally posted 72 months ago. (permalink)
tschnitzlein edited this topic 72 months ago.

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mic.mark says:

tschnitzlein [migrated to Ipernity] - Simply trying to achieve this:

It's easier to eliminate stray RF as a cause of this problem by shutting the flash in a microwave than to hunt for local HAMs. If it still pops in the microwave, then that rules out RF interference and points to manufacturing defect. If it stops popping when shut in a microwave then it's stray RF and a replacement unit will not help.

I didn't suggest attempting to pop the flash from inside the microwave.
72 months ago (permalink)

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giwo says:

Interesting side note as to why some of the units with the same board may not work with one another. When I ordered my original trigger the pt-04 rf-04 combination was on backorder, so I order a single pt-01 rf-01 so I would have something to play with until I got the 4ch units. For those that don't know the 01 series doesn't have the dip switches and are a single channel. When my 2 4ch units finally arrived, I decided to do a little investigating and found that both units used the same circuit board, but the 01 had no dip switches. This situation was remedied easily enough but neither the transmitter nor receiver worked with the 4ch units. A little more investigation uncovered that both the receiver and transmitter of the single channel unit lacked a surface mount resistor that the 4ch units had. I scavenged a couple of matching resistors and suddenly found myself with 3 work transmitters and receivers. I would not be suprised if they used a similar scheme on the 4ch and 16ch units.
72 months ago (permalink)

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Entropy512 says:

I recall hearing somewhere that certain versions of the Cacti had issues with spontaneous triggering from Canon flashes.

I'm a Pentax user so I don't remember the details unfortunately.
71 months ago (permalink)

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EdwardHor.com says:

Would any of these antenna's work?
www.rfmodules.com.au/misc/ant.htm

Namely the helical stubby one?
71 months ago (permalink)

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Alfredk says:

You did mention improving the sync speed of this triggers? Well let me tell you, I shot a good portion of the afternoon today during a workshop with Don Giannatti and the GI's we were using triggered at 1/1250 with out any issues. So how much more sync speed do you want? The sync speed on this little triggers are mostly limited by the camera you use, I used my Nikon D70. Don is my witness :)
71 months ago (permalink)

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Entropy512 says:

For whatever reason, with some cameras the Cacti are SLOW.

My Pentax K10D and K20D sync at 1/180, but the Cacti can only do 1/125.
71 months ago (permalink)

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`Mark&Manna Photography is a group moderator `Mark&Manna Photography says:

@ alfredk...An afternoon with Don Gianatti? Now you're just BRAGGIN'! :-)
71 months ago (permalink)

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shovitswe says:

My K10D syncs perfectly with Cactus V2.

00 and 11 made the difference.. When 11 gave black bar 00 didn't.
71 months ago (permalink)

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Alfredk says:

Mark& Manna, no bragging here, I actually spent all day with him, Briana and 10 more photographers, we had a ball.
71 months ago (permalink)

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OliverDavidPatrick says:

@shovitswe: what do you mean by "perfectly" ? can you please tell me your results in maxing out sync.

I have a Sony R1 (leaf shutter) and "only" get 1/400 to 1/500th of a second, where normally (cable or on hotshoe) I get 1/2000.
71 months ago (permalink)

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shovitswe says:

@ Oliver

Perfectly for me is filling the whole frame at x-sync.
I synced at 1/750 with a D40.
Originally posted 71 months ago. (permalink)
shovitswe edited this topic 71 months ago.

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`Mark&Manna Photography is a group moderator `Mark&Manna Photography says:

Perhaps it's my own jealousy that makes your post seem like bragging, alfredk.....:-)
71 months ago (permalink)

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rudy__ says:

I have a Sony R1 (leaf shutter) and "only" get 1/400 to 1/500th of a second, where normally (cable or on hotshoe) I get 1/2000.


You get "only" 1/400 to 1/500? Poor guy. I wonder what you actually get at 1/2000 though. Does your flash fire just as the shutter is opening, or half way through, or much before but still overlaping the open period, or ...

When you are talking about this range then you also have to consider the response time of the camera (when does the trigger pulse happen) and the response time of the flash.

The measurements I have done with a V1 wireless pair has been able to produce a trigger signal out of the receiver 640 micro-seconds after the trigger was presented to the transmitter inputs. This is the fastest it can do (and pretty fast at that). This was with a very good rf link with a tuned modified transmitter.
71 months ago (permalink)

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Jerry P. H. says:

I did not read the whole thread, but:

"Can anyone who owns a combo of 16-ch and 4-ch equipment try seeing if they can trigger their 16-ch equipment with a 4-ch? It looks like the 4 channels of the 4-ch version are a subset of the 16, and the transmitters actually use the exact same circuit board..."

I can vouch to you that I was told that they can. I bought 2 X studio strobe 16ch ones with 3 X four-channel ones, and was told by Mr Chan from GI that the 4CH transmitter will all trigger all receivers, 4 and 16 channel ones.

I should be receiving my GI setup in about 2 weeks.
71 months ago (permalink)

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rudy__ says:

The four channel unit is a 16 with 2 switches (4 combinations) compared to the 4 position (16 combinations).

At a recent shoot some of the guys that were using the four channel models had problems with their transmitter (unmodified). I had a 16 chanel transmitter that I used to trigger their strobes after I determined the switch combination equivalent to their receivers.

Now this was with a V1 transmitter. I didn't take a look at their receivers but they were the ones with the hotshoe connection. I don't think they were the V2s. The receivers I use are the type with the 1/4 phone plug and the internal AAA batteries.
71 months ago (permalink)

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Chris_Malcolm says:

I understand from previous discussions that the transmitter sends a string of coded signals. So the reason why sync speeds tend to go down as distance increases is simply poor reception -- if the receiver fails to identify the first code it might identify the second or third and fire on that. It's a common observation that mods which improve range often improve sync speed.

With regard to best antenna length, it's more complicated than simply getting the theoretically correct length for the nominal frequency. This is a cheap transmitter with secure stable frequency control, and the electrical characteristics of the aerial will affect the transmitter frequency. So the theoretically best aerial might produce the best signal, but have shifted the frequency away from the best frequency for reception.

So if you really want the best length of aerial you need to do some aerial length experiments , and check out the final result with all your receivers.

It's easy to do aerial length experiments with bare wire, just keep bending it over and keeping both sides of the bend in contact.

Note also orientation: you get best reception if the transmitter and receiver aerials both point the same way. Since the most usual receiver orientation is straight up, and the unmodded transmitter orientation is flat on its side, adding any small bit of vertical wire to it is likely to improve things simply because of orientation.

As many have observed, however, often pretty much any few inches added makes a really big improvement. Mine went from max distance of about 20 feet to about 200 without much difficulty. My biggest difficulty now is that I probably need an expedition and an assistant to experiment with longer distances. I can't be bothered :-)
71 months ago (permalink)

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rudy__ says:

Frequency stability is not really the issue with the transmitter. The problem is that a lot of people for a wavelength calculation as to the proper wire length for the 433Mhz frequency then they coil it up to reduce the length. Sorry but that is not the same thing.

Then there are some people that have an antenna and a length connecting wire that for some reason they think should be ignored because it is not part of the physical antenna.

Also the output amplifier is expecting to see a certain load. While an antenna might be optimum for radiation at a certain frequency that does not mean that you can just throw that on the output of an amplifier and everything will be fine. There have been a number of reports where people have used the correct 1/4 wavelength wire and the performance was worse than no modification.

The foil strip has a certain characteristic at the operating frequency. In order to deal with the impedance mismatch a compensating capacitor is typically used to tune out some of the reactive component of the impedance. I believe C3 is used for this.

Now when PhotoJoe sticks a 433Mhz antenna on these he may have a good antenna but it is not matched to the output of the amplifier in the transmitter because of the compensation that was used in order to use the little PCB strip antenna. And then on top of that most people leave the rest of the old antenna trace in place, expecting it has no effect in the circuit.

There is a lot going on here and the variable results reported is due to that. Fortunately almost any change will produce better results.

Another misconception by some people is that the different "channels" are different frequencies. This is wrong. All that the dip switch does is alter the code sent on the same frequency.
Originally posted 71 months ago. (permalink)
rudy__ edited this topic 71 months ago.

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NormMonkey says:

Entropy512, do you happen to know what the pulse width of the receiver output is? I don't have the equipment handy to measure it, but I'm wondering if the output pulse of the cactus triggers is enough to trigger a camera shutter via a remote release.

I've read that the pulse width for the shutter release signal on shutter release cables varies, but tends to be around 20ms. (for debounce).
71 months ago (permalink)

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OliverDavidPatrick says:

@rudy 216: "Fortunately almost any change will produce better results." well said !

So you're saying I'd have to fully insulate (electrically) my transmitter (sender) and even dremel off the short piece on the board which used to be the antenna ?

As far as my research went there are a few weak points that can be easily fixed:

1. Transmitter needs antenna ! Dunno which one, often a little wire works fine - be patient in finding the right antenna / wire length.

2. Power Source of the RECEIVER: the silly battery mount inside the receiver is - well, it's silly. It has proven to lose contact very often and those silly 3v batteries are a bit more expensive than others.

So: change the power source to 2x 1,5 V AA Alkalines from Walmart or similar or even 2x 1.2 V NIMH's will work just grand in an external battery pack.

Skillfully use your soldering iron to remove them silly clamps and solder a cable to the board - leading to your external battery pack.

3. Receivers which are picky on when they fire can be easily fixed by heating one of the soldering points of the antenna and prying the antenna out or in of the board.

Cactus v2s receiver / trigger after modification


ONE PIECE OF IMPORTANT ADVICE:

while you are playing with your v2s and testing in between wheter or not the performance (range and reliability) has improved don't get too close to the receivers when hitting the test button on the transmitter.
You can stand a good bit away, and if they work move closer.
The point of it is, that if you are too close to the receiver you don't know wheter you new antenna is working, because at very short distances the antenna doesn't come into play and has no effect whatsoever.
But while you're testing you want it to have an effect of course in order to know what you're doing.

Also do not put the receivers beside each other while testing, sometimes even perfectly working receivers will not work when they are too close to each other.

This is important because you don't want any false feedback while testing, it could lead you to the wrong conclusion.
Originally posted 71 months ago. (permalink)
OliverDavidPatrick edited this topic 71 months ago.

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rudy__ says:

Before anyone tries step number 3 above read this thread.
www.flickr.com/groups/strobist/discuss/72157605428918407/...

If your receiver never worked then you have nothing much to loose. But if you are just trying to get more than typical range then you are asking for trouble.

Also do not put the receivers beside each other while testing, sometimes even perfectly working receivers will not work when they are too close to each other.


This is true. These radios are of a simple design. The receivers can output enough energy in the antenna circuit to effect one another if they are too close.

Generally be very cautious about advice on these wireless triggers. Almost everyone has an opinion but there have been very few people here with enough (if any) background in RF design to provide any accurate answers.
Originally posted 71 months ago. (permalink)
rudy__ edited this topic 71 months ago.

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OliverDavidPatrick says:

Indeed, I have no background in RF. But I did everything step by step and got 2 jerky receivers (out of 4) to work perfectly after only performing this one thing with the receiver antenna.

All I can say for sure is that it worked for me on both right after only performing the antenna thingy on the receiver - I don't know why though...

Maybe that stupid wire that I slightly moved is part of a cirtuit which tunes to the frequency or in fact it's the actual antenna. I tried straightening it (it was slightly bent already) and bended it back with no success. Hell, I've honestly tried everything but the only thing that worked is the thing above.

Oh, and btw: still running on my first set of batteries, no moodyness when it comes to performance. They work straight - day in day out - without misfires or even random pickups (hickups ?)

Even dropped em a couple of times, but they refused to die and kept on working. Still I would like to pour some epoxy into the housing sometime I get a hand on that stuff.

It's not the ultimate radio trigger as this product can only be called a joke, but for the starving strobist like me it's good bargain for the money and it let's me educate myself lighting-wise.

If you want to work professionally though, you need digitally coded channels, so nobody will start firing your flashes. Aaaw, I would so much like to organize / participate in a Berlin Strobist Meet, but with the Cactus that's not gonna happen....

EDIT: @rudy: stupid me, I just read the thread (you posted the link above). Thanks for the info
Originally posted 71 months ago. (permalink)
OliverDavidPatrick edited this topic 71 months ago.

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OliverDavidPatrick says:

@rudy: one last question: would you think it would interfere too much with the circuit functionality if I bent the little board which is on 90° angle almost flat against the main board (whithout touching it of course) ?

I would like to get a different housing for my cactus and also a different switch, which makes it easier to see whether they're on or off.
71 months ago (permalink)

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Entropy512 says:

"Frequency stability is not really the issue with the transmitter. The problem is that a lot of people for a wavelength calculation as to the proper wire length for the 433Mhz frequency then they coil it up to reduce the length. Sorry but that is not the same thing."
You're correct about frequency stability. Cheap as it is, it's crystal-controlled. (Actually nowadays the cheapest way to make a single-frequency transmitter is to use a crystal...)

"Then there are some people that have an antenna and a length connecting wire that for some reason they think should be ignored because it is not part of the physical antenna."
Yup, unless the wire is a matched transmission line (coax, twinlead, etc), it will have an effect. This receiver probably doesn't have a 50 ohm output so it would be next to impossible (and not worth it) to try and add such a transmission line.

"Also the output amplifier is expecting to see a certain load. While an antenna might be optimum for radiation at a certain frequency that does not mean that you can just throw that on the output of an amplifier and everything will be fine. There have been a number of reports where people have used the correct 1/4 wavelength wire and the performance was worse than no modification."
Yup, 1/4 wave is optimum for an approx. 50 ohm impedance. With this amplifier - who knows what the best length is, because no one has measured the amplifier's source impedance.

"The foil strip has a certain characteristic at the operating frequency. In order to deal with the impedance mismatch a compensating capacitor is typically used to tune out some of the reactive component of the impedance. I believe C3 is used for this."
Makes sense to me, although if I recall correctly (Smugmug and hence my own pictures are blocked here) that's a series capacitor, so it could just be DC blocking.

"There is a lot going on here and the variable results reported is due to that. Fortunately almost any change will produce better results."
Yup.

"Another misconception by some people is that the different "channels" are different frequencies. This is wrong. All that the dip switch does is alter the code sent on the same frequency."
Definately correct.

As to the person who asked the pulse width - I have no idea. It can trigger my Pentax K20D though.
71 months ago (permalink)

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rudy__ says:

@rudy: one last question: would you think it would interfere too much with the circuit functionality if I bent the little board which is on 90° angle almost flat against the main board (whithout touching it of course) ?

It should be OK. The actual receiver is a standard component that can be used for other products and with a different orientation. Now the reception pattern might be a little different but I doubt it would be any worse than it is not.

I don't doubt that your pulling out the loop antenna wire helped you, but for someone else's radio pulling it out could make things worse. From the correct center point there are two directions. If it was too far out, and you continued to pull it out, it does not get you where you needed to go. Some day(s) I will spend some time analyzing these units but I don't have time for it now.

As to the person who asked the pulse width - I have no idea. It can trigger my Pentax K20D though.

From my tests on these things (from what I remember) the pulse will be as long as the trigger presented on the input. With the transmitter, if you hold down the switch it will keep transmitting until you release it. The momentary flash of the LED is not tied to the length of the transmitted output.
Originally posted 71 months ago. (permalink)
rudy__ edited this topic 71 months ago.

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tim-johnson says:

Dang, I feel stupid after reading this. Maybe I should adapt the phrase, "I are a football player".
71 months ago (permalink)

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OliverDavidPatrick says:

@rudy: thanks for the advice on the orientation of the board.

Of course I also meant one should try to move it in as well, not only out.
Didn't see why I should have mentioned it, it just seemed too obvious.

Time is running out, once the Radiopopper JR. are out the Cactus v2s will become just too unattractive to buyers - unless they don't know about the Radiopopper JR's...
71 months ago (permalink)

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rudy__ says:

Didn't see why I should have mentioned it, it just seemed too obvious.

Maybe to you and me but a lot of people take these instructions literally.
Originally posted 71 months ago. (permalink)
rudy__ edited this topic 71 months ago.

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rudy__ says:


"The foil strip has a certain characteristic at the operating frequency. In order to deal with the impedance mismatch a compensating capacitor is typically used to tune out some of the reactive component of the impedance. I believe C3 is used for this."

Makes sense to me, although if I recall correctly (Smugmug and hence my own pictures are blocked here) that's a series capacitor, so it could just be DC blocking.

Driving in to work my thoughts touched briefly on this. Funny how the mind needs to keep busy.

The antenna trace after C3 does not connect to anything else. (see photo at top of page) So what if there was DC on the trace. It would have no effect as far as the antenna was concerned. If C3 was for DC blocking then why would it be necessary?
71 months ago (permalink)

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PSL images says:

I have 3 sets of these RF604's and I have modified the antenna differently in each TX,
I used a loose wound coil inside the case, another fed vertically through the case to make a proper antenna, and a simple whip antenna on the third, each was made at 1/4 wave length.
The whip appeared to give the best range, but was impractical, the external antenna was almost as good as the whip and far more practical, and the internal coil was a little better than no mod at all. I connected the antennas at C3 and disconnected the remaining track.
I'm now wondering about some RX mods, sometimes I find the RX suddenly stops working for no apparent reason, I have also noticed that sync speed is best when new batteries are fitted, and I wonder if the battery voltage is a factor, I'm going to try a 3.6v supply using a 5v regulator and 2 diodes in series with the output, which should provide the ballpark voltage from a standard 9v battery and see how it affects performance.
48 months ago (permalink)

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