This circuit was found in a 1968 documentation. It makes use of both NO and NC reed-switches and small magnets attached to a card in the form that results in the drive combination.
The purpose of this circuit is to increase the sensitivity of a common multimeter in its voltage...
This is the modern version of the Galena radio in which the detector is a germanium diode (which can...
This circuit allows the measurement of very weak currents indicated on an analog instrument or...