In this project, I'll make a small circuit capable of controlling a servo, it is a servo tester made out of a 555 timer IC.

Your circuit must use only one transistor, no ICs. Diodes and RCL passives are allowed, but also no vacuum tubes, tunnel diodes, or other active components, you lateral thinkers.

Design Squad engineers Judy and Adam show you how to make a mini-alarm.

How difficult would it be to build a feed-back circuit that would automatically compensate for colder nights/warmer days, etc.