This high-sensitivity circuit was found in a 1980s documentation. The source can be a 9 V battery with a splitter to make it symmetrical. The shock can be 200 uH or more.
This narrowband data receiver is from the Philips Databook of 1990. The circuit is powered by 5 V...
This circuit was proposed by an old American documentation for listening to SSB stations. The...
This voltmeter for continuous voltages has several scales and is totally passive. The diodes are...