This circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit is based on a 741 that activates a buzzer with oscillator. R5 adjusts the sensitivity.
Found in an American publication from 1968, this circuit can be made based on a TIP42 that must be...
The circuit is suitable for small animations, with the movement effect of the LEDs in a matrix...
This power supply is indicated for the supply of not very powerful car radios of the AM and FM...