This simple metronome, from 1985 documentation uses only transistors and has two settings. For voltages above 6 V, up to 12 V, replace the BC557 with a BD136.
We found this circuit in an American technical documentation from the 1980s. The integrated...
This circuit is from a 1986 Revista Española de Electrónica. It consists of an amplifier with...
The timing of this timer found in American documentation depends on capacitor C1. This component can be...