We found this configuration in a 70s American documentation. The circuit makes use of operational amplifiers of the time. Modern equivalents can be tested.
This circuit is from an old American publication, using transistors of the time and operating with a 48...
This high quality audio preamplifier uses three bipolar transistor and is powered from 24 V...
The circuit shown in the figure allows a pressure switch to be used to turn a load on and off in a...