The "timer" is the guts of a wind-up toy that I parted out. As the shaft turns it pulls the string which is connected to a contact on a spring which completes the circuit to the igniter deploying the parachute. The big problem with this design is that and soon as the toy started to unwind there was 15 seconds to screw the recovery coupler on, tuck the parachute in, put the nosecone on and have enough time for the rocket to launch and get up in the air. It didn't work... don't know why. I thought it was inventive though.
