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.
This circuit can be used as a shield for microcontrollers. The relay is power compliant, and the...
This Texas Instruments integrated circuit, available from Mouser Electronics, has a 91 dB common...
We found this circuit in a Radio Electronics of the 90s. The integrated circuit used is not common...