We found this circuit in the May 1996 Electronics Now magazine. The relay must have a voltage according to the circuit power supply and a trigger current of no more than 50 mA.
Found in a 1980s American documentation, this circuit appears with variations elsewhere in this...
The circuit shown, with the printed circuit board, was found in an article in the June 1990 issue...
This interesting circuit converts BCD signals into a voltage that can be used in an analog...