This circuit was found in a 80's Popular Electronics. The sensor can be any phototransistor. The circuit is indicated for an audio link modulated in pulses.
With this circuit it is possible to have a symmetrical source from a simple source with voltages from...
The basic idea of the circuit shown in the figure is to increase the brightness of an ordinary...
This regulator can use BD'136 as the main transistor and as a reference next to a BC548 zener. The...