KAP Video Switch
This pair of doodads lets me have up to 9.5V of switched, regulated power on my KAP rig for driving video hardware. The switch in the upper left goes in my RC transmitter. The circuitry in the lower right goes on the rig. Here's how it works:
The switch is a quad-pole, double-throw switch. Three of the four poles wire into one of the channels on my transmitter. Two 5k potentiometers are wired into the switch, which will feed the signals from one or the other into the RC radio. By dialing in two settings on the two potentiometers, the switch lets me flip between the two.
The fourth set of poles is used to control power to the video hardware on the ground. Flip it on, the hardware powers on. Flip it off, it all goes off.
Meanwhile up in the air, an RC switch from Pololu Robotics is wired into the channel that is tied to the switch on the ground. When the ground switch is flipped on, the RC switch powers on. When it's flipped off, the RC switch powers off.
The switch, in turn, is wired into a 2.5-9.5V boost regulator, also from Pololu Robotics. (They also make one that goes up to 25V.) This boosts the +Vbatt and Gnd lines from the RC channel to a regulated +9V and Gnd on the twisted power lines coming off the two boards. This plugs into the video transmitter on the KAP rig.
The net effect of all this is a switch on my transmitter that turns ALL my video gear on and off, both on the ground and in the air. It also eliminates the need for a second battery on the KAP rig strictly for the video.
A hidden benefit of this is that as long as the supply voltage is above 1.5V, the boost regulator will continue to supply 9V to the video hardware. I'll notice the sluggish servos on the rig long before the video will fail.