This circuit is an alternative to the previous circuit. We found it in the same article in the Radio Electronics magazine of March 1992. The integrated circuits are the LM3914.
This instrumentation amplifier with differential inputs was found in documentation from the 90s....
This circuit is from a Radio Electronics magazine from December 1958. The indicator instrument is analog...
Found in a 90s 303 Circuits, this circuit has an output power of 100 mW. L1 consists of 890 turns...