This circuit is learning about audio signals receiver through the air.
The circuit uses to take sound signal that feeds to reach the circuit round of electric heel one line at has low impedance the location around room or other area that cover the perimeter of the checking L1 be a wire involves on plastic axle of 100 – 500 amount receivers s round.
The part of op-amp that use of Motorola number MC3401P or of NS number LM3900? which be Op-amp 4 pcs.
The power supply can use since 9V-15V. This circuit can use the circuit calls model the individual. If power amplifier circuit of a transmitter has input that use Micro phone get.