We found this circuit in the April 1978 issue of Radio Electronics magazine. The 2-digit circuit uses common TTL integrated circuits and must be powered by a voltage of 5 V.
In the figure below we have the main configurations of power supplies with the most used...
This circuit is a high voltage source for a gas LASER. We found it in a documentation from the...
This integrated amplifier was used in televisions from the 70s, with good sensitivity...