Overvoltage Protection

This is a tried and trusted design for the protection against overvoltages that can be configured for your own needs. The circuit can also be used to detect undervoltages; in that case the inputs of IC1 have to be changed over.The operation is straightforward. When the input voltage becomes too large, the voltage at pin 2 (inverting input) of IC1 becomes higher than the reference voltage at pin 3 (noninverting input). The output of the opamp will in that case become ‘low’. (It’s just like a maths lesson: higher times inverting can be thought of as + times – and that results in – .)