This wired intercom circuit was found in an English publication from the 80's. The integrated circuit can be replaced by an equivalent, just like the transistor which is a general-purpose type.
This circuit uses a small photocell to trigger an auxiliary flash. The circuit is from a 1991 PE...
A touch of the X1 sensor causes the motor to be activated for a time that can be adjusted in P1....
This circuit allows the division of the frequency generated by an oscillator with the 4069 by two,...