This QST circuit generates 4 frequency signals according to the crystals used. Transistors admit equivalents although the indicated types can still be found with some ease.
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...