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.
We found this circuit in a November 1970 Radio Electronics. It uses a PUT or programmable...
We found this circuit in a technical documentation from the 1970s. It converts low frequency...
This modulated siren was found in the December 1974 issue of Radio Electronics magazine. A higher...