This circuit for an optical audio link using LED or LASER was found in a 90s QST magazine. The circuit can use operational amplifiers like the 741.
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...