I have a PerfectFlite Alt15K altimeter, and because of the tall grass at Bong, am planning on getting a beeper. However, the commercial ones require their own batteries. It seems a better solution would be to have all of the circuitry in the electronics bay running off of one power source to save weight.

I could build a beeper circuit, but I like how the commercial ones are launch activated. Anyone dealt with a similar problem? I'm thinking that if I get a better altimeter that doesn't require a funny battery size/voltage and has the means to trigger another circuit, I could use it to activate a homemade beeper.