Found in an old Popular Electronics this circuit appears in other variations on this site and in this section. It uses a 7-segment common anode LED display as an indicator.
The HV2405E integrated circuit is not very common these days. This circuit was found in the August...
This circuit was found in an American publication from the 60's. Transistors are germanium types of...
This strobe light circuit for car spot adjustment dates to 1987, when there were no electronic resources...