This low noise microphone preamplifier circuit was found in American documentation from the 90s. The circuit requires special care with the layout. The power can be between 9 and 18 V.
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...