Homebrew PCBs

oprystar wrote:
> Hello all,
> 
> I am wanting to build a seeking device (camera), or thermal heat 
> detector. No need for LCD, a blinking LED would be fine. I want to 
> use it to track game for hunters who can not recover wounded game 
> (mostly deer)that has been shot and difficult to find.
> 
> I have seen units for this in major sporting goods magazines and 
> websites. I think they are called game trackers.
> 
> Does anyone have, or know of, a schematic or layout for this or 
> similar device?

Just need a lens that focuses onto an IR photodiode. The lens needs
to be transparent and a low noise preamp connects to the photodiode.
AC couple the DC output of the preamp to an audio circuit. For
more sensitivity, use an optical chopper and synchronous demodulators.