Found in a 90s Popular Electronics, this circuit uses a simple 9 V source. The power can be used from the circuit with which it works.
Using in operational amplifier is possible to increase the dissipation power of a zener. This...
This circuit produces a whistle sound when acting on switch S1. Aids is applied to a transformer that is...
Found in an old Popular Electronics, this circuit has a gain of 20 dB. The integrated circuit is...