Found in a 90s Radio Electronics, this circuit uses a ceramic capacitor (C1) as a sensor. The operational amplifier is a double 741 of the time.
This circuit allows the measurement of very weak currents indicated on an analog instrument or...
Found in National Semionductor documentation this circuit combines a tone control with an...
Found in a 73 magazine from the 1980s, this circuit generates signals from 3.2 to 22 MHz. FETs can be...