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.
The integrated circuit used in this filter is not very common today, but the configuration can be implemented...
In fact, this is the circuit also known as “vox”, that is, a relay triggered by sound. This...
This circuit makes it possible to reverse the direction of a DC motor through a relay controlled by a...