Re: CMUCam and low voltages
 

Well, not that it matters on the main breaker; once it goes, it goes! But you are right. If your voltage drops for just a second, your camera's gone. However, I wonder, wouldn't the camera simply reinitialize as soon as the RC came back? It would be the equivalent of a power off reset.

Re: CMUCam and low voltages
 

Your code would have to detect such a reset and reinitialize the camera - it would lose all of its registers. That's why it's a big deal.

Re: CMUCam and low voltages
 

Our camera works fine on the 5 volt supply of a free analog input port in our experience.

EDIT: Looking at http://www.cs.cmu.edu/~cmucam2/CMUcam2_manual.pdf, it seems that the internal circuitry regulates the voltage to 5V anyhow.

Re: CMUCam and low voltages
 

Doesn't the CMUCam have a nice big capacitor to filter the input power? And if it doesn't, wouldn't any good regulator design put one in? That would be able to prop up the camera power during momentary 12v sags.

And yes, I've cut power to the camera and it does link back up within a half a second. But in the 10-second autonomous, if that keeps happening, it could be bad... :)

Re: CMUCam and low voltages
 

The original post was that the camera started acting weird and calibration values changed with battery voltage. What you were experiencing was the power regulator on the camera was providing a varying voltage to the camera linear circuitry and therefore changing the RGB values provided to the rest of the camera.
As Mike and others pointed out, prior to the backup battery being introduced many teams were having problems with the RC and modems dropping out during competition. Frequently, the main battery is pulled down to as low as four volts on multi motor or inefficient designs. The RC requires at least 7 volts to operate and with a lot happening, IFI had designed in a dropout that would reset the RC when the input fell below 8 volts. The RC would take a few seconds to boot and then it had to reestablish modem link before the systems on the robot would be enabled. With the introduction of the backup battery, the main processor and radio modems stayed powered and linked when the main battery falls below the 8 volt cutout. A by product of the backup was the ability to use it for servo power and eventually the camera. Since RC output is controlled through the arena controller, the ability to power the camera when the robot is powered on and have it initialize before match start is a great benefit.
Please remember that the spare 5 volt output is after the main regulator in the RC and that will respond to main battery voltage less the 2 volts dropped across the regulator. Capacitors wouldn't be able to keep the power up in the camera long enough. The camera draws some serious current.