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Cheap calculator hacking Answered

I put together a Solarbiotics Magbot Pendulum and it has a period of one second. I measured this by using a stopwatch and counting the swings for five minutes. . What I would like to do is count the number of times it swings back and forth over an extended period of time, for example 24 hours.   I came across an article showing how to use a cheap calculator to count the number of turns a shaft makes. A cam attached to the shaft presses the "+" key each time the shaft turns one full turn. to use it, you clear the calculator and press the "1" button. Then every turn the cam presses the "+" button and 1 is added to the sum being displayed. Every cycle of the pendulum causes the LED to flash (pulse)  once. I'd like to use these pulses to do the electronic equivalent of pressing the "+" button.  It might be possible to count these pulses using electronic circuitry (decade counters) but electronic calculators only cost about a dollar of two and I'd like to give that a try. Any suggestions would be appreciated.

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petercd

5 years ago

I rigged a small magnet on a wheel and wired a reed switch to the calculator's equals pad to count the number of turns. I somehow think a magnet might slow down your pendulum though, perhaps something in the optical sensing range might be better, then again that would probably involve more supporting electronic components.