This circuit was found in the September 1972 issue of Radio Electronics magazine. The circuit uses an operational amplifier of the time and a symmetrical 9 V source.
With a coil formed by 7 turns of 26 AWG wire this circuit operates in the 27 MHz range. But you...
The circuit shown is a commercial electronic voltmeter sold in Japan in the 1960s. The circuit is fully...
This amplifier for recording heads was found in a Radio Electronics from September 1963. The...