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 circuit shown in the figure can be used to detect the operation of infrared sources whose...
Found in a 90s Hands On Electronics, this small preamp finds applications like microphones and other...
This circuit was found in a 90s Popular Electronics. The frequency is determined by R3 and C1 that...