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.
The LED is optically coupled to the LDR1 sensor to provide negative feedback to the circuit and...
The idea of this circuit is a resistance meter or continuity test with a common microammeter or...
This selectable constant current source was found in an English publication in 1983. The...