This circuit was found in a 73 amateur radio magazine from the 90s. An LED extends the scale from 0 to 5 V to 10 to 15 V in this bargraph circuit. Other zener values can be used.
This low voltage lamp flasher can be powered from 12 V supplies. Frequency is adjusted by P1 and...
The transistors in this circuit, found in an American publication in 1975, can be replaced by...
This circuit, from an old publication, can also use modern transistors. Note that the unit is...