This circuit for old photo enlargers was found in a 1970s RCA manual. The components are from the time, but modern equivalents can be used.
This circuit is from a 1995 publication; The current is obtained by dividing 1.25 by R1. The...
We found this circuit in an old American publication. It is possible to test common FETs using a...
This circuit was obtained in a 90s documentation from Analog Devices. The sensitivity is in the...