Found in a Popular Electronics from the 90s, this amplifier uses an integrated circuit from the time. The circuit operates from the LF band up to 600 MHz with a gain of 16 dB.
This proximity relay circuit was found in the July 1990 Radio Electronics magazine. The supply...
This circuit is from an old operational amplifiers manual. However, the setting applies to modern...
Using an operational amplifier, the figure shows how to convert the waveform to low frequency...