This circuit was suggested by an Electronic Design from the 90s. Its purpose is to detect resistance relationships in circuits with resistive sensors for control purposes, by firing a relay.
This circuit is from an August 1984 Radio Electronics magazine. It monitors the state of a RAM...
In the figure we have the way to obtain an adjustable constant current source of 2 mA. The...
Found in a Maxim publication from the 90s, this circuit generates signals from 10 to 25 kHz with a...