This circuit for incandescent lamps was found in the January 1980 Radio Elecronics magazine. The sensitivity can be controlled by a potentiometer and the microphone used is of the dynamic type.
This circuit converts BCD inputs to analog voltages. The operational amplifier must be powered...
This circuit is suitable for the calibration of old analog oscilloscopes. It was found in...
This is the circuit of a hearing aid amplifier manufactured by Sony in the 1960s. The circuit was...