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 generates pulses at a frequency that can be adjusted by a potentiometer. The circuit is...
This 1.5 A circuit is from the LM117 manual. The LM350 can be used for higher current, and the...
The circuit shown is from the 1994 Linear Applications Handbook by National Semiconductor. Other...