The integrated circuit used is uncommon today. We found this configuration in Motorola's 1990 Linear Databook. The triac can be any of the TIC series.
We found this circuit in an old American documentation. SCRs can be modern equivalent types. The...
We found this circuit in a 1990 documentation. The operational amplifiers are type 741 and the LED is...
This fast-acting circuit uses a 555. We found it in the November 1992 Radio Electronics magazine. The...