We found this circuit in a 1965 magazine. The circuit can be assembled with current equivalent transistors and the precision in generating the frequencies depends on the tolerance of the capacitors.
This circuit works with small 5 V incandescent lamps but can be modified to operate with LEDs. The...
This circuit found in Radio Electronics can be used in games to produce a random pulse train. The...
This photometer is based on a Wheatstone bridge that must be balanced by the linear potentiometer P1. The...