Found in a documentation from the 90's, this circuit already includes an amplification stage. The 12 V power supply allows its use in the car.
The gain of this amplifier is controlled by light shining on an LDR. The circuit is from a Radio...
This circuit produces a whistle sound when acting on switch S1. Aids is applied to a transformer that is...
This filter that rejects a frequency range determined by the double-T was found in the August 1993...