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Best switch to detect motion?

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Emergentinsight

New Member
I have a mainly plastic disc that rotates on a shaft. Currently there is a mechanical arm that activates a switch which turns on a 9 volt LED light if the disc moves. I would like to update this to an micro switch that detects the movement of the disc. I am not opposed to mounting something on the disc as long I can keep it balanced. The low voltage DC switch must not create a drag on the disc and could be located next to the disc. The switch must also work at 0 degree Fahrenheit temps. What type of switch would you recommend and where can I obtain them?
Please let me know if you have questions.

Thank you for your help,
Steve
 

Grossel

Well-Known Member
You don't use mechanical switches for that, you use an optic detector. You need to look for one that has the sender and receiver placed next to each other but in a slightly different angle.
Look for "optical proximity detector".
 

KMoffett

Well-Known Member
Could you post a good photo of the current setup?

Ken
 

JonSea

Well-Known Member
Most Helpful Member
Along the same lines as Grossel suggested, you could use an optical sensor like this one from Elecrow. You could put a piece of reflective tape on the motor shaft or even a light/dark contacting line on the disk and aim thus sensor at it.

The sensor would output a string of pulses when the motor is turning (and either a high or low level when it's stopped). You would then need some kind of a circuit to signal when there is not a pulse stream that the motor stopped. I'd probably reach for a micro to do this but I'll bet others here could come up with a 555 timer circuit or something equally as simple to control a light or relay.

SmartSelectImage_2017-03-10-05-10-16.png
 

large_ghostman

Well-Known Member
Most Helpful Member
If the mechanical arm is metal you could use a hall effect sensor? But optical is better
 

JonSea

Well-Known Member
Most Helpful Member
Micro = microcontroller. You might recognize these as an Arduino but I use Microchip PIC18F-series parts and Swordfish Basic for my programming.

That's a bit of overkill and I'm sure a 555 timer chip could be set to trigger if the pulse string stopped.
 

Tony Stewart

Well-Known Member
Most Helpful Member
Show your plastic disk. Optical reflection method will be determined by reflection index marking. (black or foil depending on background.)
 

Emergentinsight

New Member
Shown in the picture above is the switch. A metal rod rides on the disc post until the reel moves. Then it drops into the metal fender washer on the back wall to complete circuit and turn on an LED. This is all housed within an 11" x 11" box of which the reel takes the majority of space. An electronic sensor would reduce the drag and could increase future enhancements.
 
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