[Laser] 5 mw laser tranceiver kit

[Tim Toast]

I guess i would just forget about the transmitter and switches and try to come up with a resonably sensitive receiver first out of this 3 volt idea. Anything less just wouldn't be right for a kit. It would be nice if it could operate from 3 volts but that's secondary to the sensitivity. If we had to come up with a kit tomorrow i would vote for the KA7OEI v3.1 receiver. It's only three transistors and a chip basically so that's not bad as far as parts count. The nice 555 chip PWM AM plus MCW for the transmitter too. 
For a laser transmitter i would avoid using a fully collimated beam (as comes out of laser pointers) unless it is mounted on a tripod. The main limitation for this is some sort of easy adjustable focusing. Maby a good compromise is a fixed 1 to 5 degree wide beam. With uncorrected laser diodes, this would be a rectangle shape oriented horizontally. With a good sensitive receiver, it should matter less about a very tight beam collimation anyway. From scratch, an easy focuser could be made out of hardware parts - such as a lens glued to a nut which screws onto a hollow bolt partway to focus. For bigger lenses, threaded PVC plumbing parts.