Found in an old Radio Electronics, this circuit applies to frequency meters for frequencies up to 100 MHz. The input impedance is in the order of 1 M ohm.
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...