This circuit is from a 1965 Radio Electronics. The triggering transformer generates high voltage pulses. The generated light pulse depends on C1 and C2.
This circuit from Popular Electronics powers a small speaker. The transistor can be of general use...
When the sensor X1 is opened, the relay is energized. When waiting, the current drained is very...
This circuit for measuring bridges was found in the October 1995 issue of Electronics Now...