This circuit activates a buzzer when the voltage applied to the input falls below a preset value in R1. The circuit is from an 80's American documentation.
The figure shows how to implement an OR function with two inputs, using a relay. The relay...
The integrated circuit used in this 1987 project is not very common these days. However, if found...
Found in American documentation from the 1980s, this circuit has a diode feedback. At the exit we...