Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors support modern equivalents. The circuit can be used as a shield.
In this game, whoever tightens the sensors, which are metal bars or spent batteries, makes the...
This two input simple mixer uses two transistor and can b e upgraded to more inputs. Input...
This circuit is from a 1987 American publication called Electronics Handbook. The circuit can be...