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.
This source of some amps for voltages up to 40 V was found in an Italian magazine Elettronica...
This circuit simulates a diode whose characteristics can be adjusted with a trimpot. The circuit is...
This circuit was found in the Philips integrated circuits manual of 1990. The integrated circuit must...