Hello All

I am putting together a coil winding set up with a variable speed reversing DC motor. On the mount where the new coil is being wound I have a magnet. And below that a simple reed switch wired to the "equals" contacts on a old calculator I never use. When you are ready to count windings ... turn on the calculator and enter on the keypad " 1 + " . And every full rotation will press "equals" button and that's it folks. Simple !!!

Dodeca

How I do love simple genius

Sweet. very useful. Good RPM calculator too.

For those of you who found this didn't work on your calculator, try entering "1++" before triggering the equals key, and this will work fine. Good idea for coil wrap counting, Dodeca. Thanks for your post.

If you are trying to measure how fast the wheel turns ... then the " debounce circuit " will prevent multiple fast reed switch closure on a calculator . But I think it's faster than the daftmans mechanical method .

To measure RPM ...

I might try a magnet mounted on the wheel that passes by a small coil once per revolution going back to the computer sound card ( mic input ).

It might work ??? 4 free

Dodeca

Ive seen this also done with a pedometer. Just pop it open and it makes sense. Micro switch activated by a cam or reed/magnet.....

HaHaHaHa
old but it works and never missed up