This circuit is from an old Japanese publication of 1962. The circuit uses two batteries, one for the filaments of the tubes and the other one of high voltage for the plate circuits.
This simple source with zener regulation is ideal for experimental projects with operational...
This circuit is from a 1977 Signetics manual. BC107 transistors can be replaced with BC547 and...
In the figure we have an old circuit for controlling two low-power lamps. The circuit is from...