This circuit is from the 80's but uses common components today. The relay is voltage sensitive according to the power supply used. Transistors may be general purpose types.
This microphone preamp allows the use of high impedance crystal microphones with amplifiers that have...
This is the radio receiver for the previous infrared alarm radio transmitter. It contains the...
This amplifier for a sinusoidal function generator uses a 741 integrated circuit. The circuit is...