This receiver circuit was found in a Hands On Electronics from the 90s. The circuit uses a PLL 561B that is not a common component today.
The existence of field effect transistors at the input of the integrated circuit (operational...
This circuit generates a siren sound. It was found in the April 1969 Radio Electronics magazine. The...
Suggested by Siliconix in documentation from the 90s, this circuit can present gains of digitally...