With only 1% distortion, this Motorola amplifier found in a 1968 documentation makes use of period components. The frequency response ranges from 10 Hz to 100 kHz.
This circuit was found in a Mullard transistor manual from 1960. Note the symmetrical power...
With the shadow over the sensor, it is possible to interrupt the sound of your amplifier using this...
This circuit puts the battery in the circuit when the voltage of a source is cut, preventing it...