Mains Hum Filter

This mains 50 Hz interference hum filter using LCR components works well if you calculate the values of the components correctly. It uses the principle of the parallel L-C resonant circuit, which tunes out the hum. If you have long intercom wires carrying audio, then chances are that it will pick up some mains hum, and therefore this type is circuit helps to filter it out. If we were to use a standard 2.0 H inductor for the coil, what is the required value of the capacitor?

Calculations

To calculate the value of the capacitor, we can use the following standard formula for resonance.

Given the inductance value (L), we need to transpose it for C as shown above.

Now, we can calculate the capacitor value.