We found this circuit in a Radio Electronics from December 1963. The circuit combines valves and transistors and has a high input resistance. The circuit is powered by two batteries.
This circuit is from a 1982 documentation. It can be modernized using LEDs in series with 470 ohms...
We found this circuit in a 1985 technical publication. The circuit uses PUTs to drive lamps....
This circuit appears with variations in other points of this section. This version is from...