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 triac temperature control circuit was found in an 80s power semiconductor documentation. The circuit...
Figure bellow shows how n flip-flops can be associated to perform a shift register. Data is...
This circuit is from 1986 documentation, being adaptable in radios of that time. The circuit uses the...