Found in a February 1949 Radio Electronics magazine, this dual tube mixer has 4 inputs. Power must come from a 250V source.
This circuit was found in old documentation and can be implemented with other operational...
Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors...
This circuit is from a publication from the 70s, but it can be assembled with any diac and a Triac...