Figure 2 - This is a tiny half inch square audio and video transmitter
I originally made my own small video transmitter but it lacked audio and was very unstable as the robot moved around or when the batteries began to drain. This video transmitter is the output block of a small security camera reduced to its absolute minimal components, allowing it to send 900MHz audio and video back to a down converter. The small transmitter was very stable for several hundred feet, had very clear audio, and ran just fine from any DC power source from 6 volts to 12 volts. Having the video transmitter on a high frequency band will also help stop interference between it and the drive remote controller, which operates on the low 49MHz band.
Figure 3 - A micro sized NTSC composite video camera with low lux CCD
It was very difficult to find a suitable micro video camera in 2004 for this project. The camera had to be black and white for use with the invisible infrared night vision LEDs, have a CCD imager rather than CMOS for clarity, and also output a standard NTSC composite signal rather than a serial bit stream. I eventually found this extremely small high resolution black and white composite camera and did a little hacking in order to remove the onboard power supply, which was 4x the size of the actual camera. This camera was perfect for this spybot now that it was reduces to only 1/4 inch square and able to run from 8 to 12 volts DC power.