The circuit shown indicates voltages from 10 to 14 V used to monitor automotive voltage. One or two LEDs light up depending on the voltage.
The phototransistor can be of any type and the adjustment potentiometer 4M7. This circuit was...
We found this circuit in a Popular Electronics from the 90s. Its purpose is to monitor a power...
This configuration can be made based on other operational amplifiers. For other frequencies, the...