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.
One 40108 Schmitt inverter or one 4093 gate can be used as a half monostable to be triggered by...
This signal generator found in Japanese documentation of 1973 uses an unusual integrated circuit...
This is the basic configuration of an operational amplifier as a current regulator. We found it in...