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 interesting logic circuit was found in a manual of neon lamp applications. | Clique na imagem...
This variation of the previous circuit produces a pulsating sound when the sensor is activated. The...
This circuit allows controlling a LASER pointer with an input logic signal. R has 10 ohm for 3 V...