This circuit was found in a Signetics documentation from the 1980s. The integrated is a PLL and the SCR is a general purpose type The pitch frequency is given by R1 and C1 as formula next to the diagram.
This circuit is from an American 80's documentation. The transistor is general purpose,...
We found this circuit in an old American publication. It is possible to test common FETs using a...
This circuit was obtained from a 1966 magazine but can be easily assembled using the 2N2646 as a...