In this 2001 circuit we have the way to trigger an SCR with a phototransistor. The circuit appears elsewhere in this section, obtained from publications from different eras.
This circuit generates signals from 0.01 Hz to 10 kHz, but uses unusual components today. The...
This 1969 Mullar circuit appears elsewhere on this site. The circuit uses germanium diodes and the...
This control circuit for direct current motors uses a 741 and an operational one of unusual power...