The starter circuit shown in the figure was found in an old European documentation. The circuit makes use of an SCR which is still common and the diac can be of any type.
We found this circuit in a 1977 publication for radio amateurs. It serves to test general purpose...
The purpose of this circuit is to amplify the signal of a medium or high impedance microphone,...
This unusual circuit from a Popular Electronics of the 90s uses LED indicators, operating as a...