Free circuit schematics - wiparat.com

This project was requested by some correspondents wishing to setup their home-cinema set adjusting all the loudspeaker outputs to the same level when heard from the listening position. In practice this device is a simple (though linear and precise) ac millivoltmeter, using an existing multimeter set to 50 or 100µA fsd with the probes connected [...]

The circuit has a flat frequency response from about 20Hz to well over 50Khz. Input sensitivity is 100mV for a full scale deflection on a 100uA meter. Built on two common emitter amplifiers, the first stage has a preset resistor which may be adjusted for a FSD. The last stage is biased to operate at [...]