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.
September 2016 - It can be obtained from Mouser Electronics a kit for developing wireless remote...
This circuit was found in an old manual and can be applied to any operational amplifier. The power...
This is a circuit suggested by Linear Technology in a 1980s documentation. The integrated circuit is from...