Found in a 1924 documentation, this circuit is powered by 3 batteries, two of which are high voltage. The output is a high impedance headphone jack.
This 1/2 hertz high selectivity filter was found in the December 1990 issue of Radio Electronics...
The two power steps below are intended for use with the SAA1027 stepper motor control but can be...
This interesting circuit, found in a 1986 publication, includes a powerful audio amplifier. Being...