SparkFun Forums

[USMCinfinity]

Hey guys, do any of you know any method or device that I can use to measure the speed of a moving table (circle)?

This is a very important aspect of calibration for a ADS calibration.

Regards,
Miguel A. Cruz

[analogon]

How fast is your table? About 1 RPM? about 5000 RPM?

[USMCinfinity]

10-20 RPM

[analogon]

You could put a mark on the table. Count the rotations for 1 minute.

If you needed more precision or wanted to display the speed continually, you could measure the period of rotation with a debounced sensor circuit and a processor. The sensor could be mechanical, optical or magnetic.

[USMCinfinity]

Know of any simple debounce sensor I could apply for this ?

[itikhonov]

Know of any simple debounce sensor I could apply for this ?

Two wires and a metal plate?

More high tech way is to use magnet + hall sensor, or phototransistor. It depends on your application.

[USMCinfinity]

I'm entertaining the idea of a hall sensor, but how would I convert the output of the hall sensor to speed?

[itikhonov]

I'm entertaining the idea of a hall sensor, but how would I convert the output of the hall sensor to speed?

It depends on application. You can use MCU with LCD or simple circuit hooked to PC via serial port, or get multimeter with counter.

Or just forget about hall sensor and use tachometer like http://www.multimeterwarehouse.com/DT6234Bf.htm

[Selenaut]

Try this: Put a strong magnet on the bottom of the table, near the outer edge. Set a reed switch (or some other magnetic switch) so that it will close when the magnet goes by. Then you can get a light to blink, or count the rotations, or whatever, when it's attached to a uC. This is how a bike rpm meter works.