We found this circuit in Radio Electronics from the 90s. The components are current. The sensor is a common general-purpose transistor. The connection to the sensor is made by twisted pair.
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...