Nichtinvertierender Integrator (Prinzip)

This circuit is designed to replace the moving coil centre-zero meter which is used as a tuning indicator in many receivers. The cir- cuit dispenses with the moving coil and provides rapid and accurate tuning. The circuit employs two (unfortunately still fairly expensive) two-colour LEDs*, and operates on the principle of adjusting the tuning of the receiver until both LEDs show the same colour.