Pendulum

Posted on Feb 6, 2014

This project is almost useless, I want just to realize a pendulum that swings endless. Nothing more. No use at all. This is not an original project but my version of a project of the past century, already seen in many different ways on the Net. This is my first time with a so small PIC. It`s very interesting. It can be used for a lot of different

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situations, substituting transistors, logic ports, NE555 and so on with a lot more flexibility. To the left, the signal at TP1 (see schematic diagram ), at the coil. Choosing the right magnet and coil, the voltage is enough to trigger a digital port of a PIC (a peak of 3V in this picture), no ADC is used. In this way the PIC can go sleeping for a long time between pulses, it works just for 10ms for each semi-cycle. The "Wake on input change" feature restarts the program every time the magnet passes over the coil. At TP3 we have the pulse that triggers the transistor for a new kick to the pendulum. I have used a PNP transistor to have a high side driving for the coil, so the pulse must be negative. The PIC10F222 works fine in the 2 to 5. 5V power supply range. The high level threshold for a digital input is related to the power supply. With 3V power supply we can see that the trigger starts when the voltage at GP1 rise above 1V. With a 5V power supply it needs an higher lever and therefore more time to start. There is a direct relationship between the amplitude of the input signal and the amplitude of the swing. Because the period of the pendulum is constant, for a larger swing (more distance to travel) it needs to run faster (V = S/t). The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit (Faraday`s Law of Induction). So, you can know if the...

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