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winchman
11-07-2005, 09:09 AM
I need a speed sensing system that will monitor the rotation of a wheel, close a switch when the wheel stops accelerating, then open the switch when the wheel stops turning or reverses direction. (I'll be happy if it going under 10rpm either direction.)

I can provide power to enable the circuit, but the circuit must become inactive once the wheel has stopped and the switch has been opened. The circuit must tolerate being interrupted at any point in its cycle, and it must start over from the beginning after being interrupted.

I can mount magnets just about anywhere in/on the wheel, or I could paint the wheel with a pattern for an optical device. The only power available is 12 volts DC.

Is there a way to do this? What kind of components will I need? How much will it cost? Is it something I can assemble from off-the-shelf items?

Roger

topct
11-07-2005, 09:22 AM
First thought, a controller from a garage door opener?

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Gene

manningrf
11-07-2005, 09:42 AM
The easiest way to accomplish this (in my opinion) would be to use a microcontroller in conjunction with a hall effect trigger. A basic stamp could be coded up to do this very easily, and it'll accept 12 VDC without modification. If you want details, drop me an email.

Michael

michael@manningrf.com

Doozer
11-07-2005, 04:02 PM
Use a PLC and an encoder or a resolver. Write the program to turn on the outputs you need. Automationdirect.com has all you need. The D-05 is a steal at $99. --Doozer

Evan
11-07-2005, 04:07 PM
Use a simple missing pulse detector circuit. Should cost less than $10.

http://home.cogeco.ca/~rpaisley4/LM555.html#22