This circuit is from the 80's but uses common components today. The relay is voltage sensitive according to the power supply used. Transistors may be general purpose types.
Suggested by General Electric in 1966 documentation, this circuit uses unusual components today....
1 We found this circuit in GE's 1977 semiconductor manual. The optical isolator uses an opto-SCR, and the...
This simple bridge unbalances according to the resistance variation in the electrodes. The circuit is...