Found in a 90’s Popular Electronics, this circuit uses a component that can be difficult to obtain today. It achieves a 10 dB noise reduction with the indicated components.
Quadrature Generator for Transistor and SCR Testing This circuit was found in US 1980s...
We found this third-order Butterworth asymmetric filter in an old manufacturer documentation. The...
A pulse triggers this 800 Hz horn for a time determined by capacitor C1. Powered by 5 V the...