This circuit was obtained from the July 1970 issue of Radio Electronics magazine. Zeners are power types that can provide a good current to the circuit. Selection is made by rotary switch.
Scratch is the scratching noise that occurs on old, scratched discs and the rumble is the...
This circuit was obtained in the magazine Eletronica Prática 9 of 1977. The Italian magazine no...
In fact, it is a RF field indicator with an operational amplifier equivalent to the 741. This...