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.
Found in National Semiconductor documentation from the 90s, this circuit makes use of components from...
This circuit was originally designed to measure capacitance with an ICL7107 but can be used with...
The TDA7000 is a Philips integrated circuit that contains a complete FM receiver with the need for...