This circuit was found in a 1980s documentation. The diodes may be general purpose diodes such as 1N34 or 1N60 and the indicator may be the lowest current range of a multimeter.
Found in old documentation, this circuit uses components that are still common on the market. The...
This circuit is from the American magazine that no longer exists Science & Electronics,...
This circuit was found in a 1969 US documentation. It provides a signal that can be externally...