• on the breadboard

    helge04/15/2018 at 15:47 0 comments

    I eventually did put this together just to see it running:

    blue: 22nF ceramic caps (used for supply bypass, NE555 pin (5)), NE567 coupling to pin5 is done with 150nF, output and loop filter caps are 10µF electrolytics. The NE567 supply is further filtered with 1µF/100V + 10R metal oxide film resistor. The pots and remaining resistor are there to adjust the NE555 frequency and attenuate the sample signal.

    In my opinion this circuit is nice and simple and illustrates well the principle of synchronous detection and the general operation of the NE567, while in a broader sense provides a different tangent to phase-locked loops and lock-in amplifiers.

    If you want a light barrier, high noise high resisitivity or low signal detection experiment as a weekend project and learn something about lock-in amplifiers along the way, this might be a fun thing to try.