Looking for a Low Cost High RPM Encoder

Technical Electrical
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#1

I need to determine the velocity of a hex shaft for a personal project, and I’m having a hard time finding hobbyist encoders that are rated for a high enough rpm (around 5-9,000.) If it comes down to it, I’ll probably buy one of Rev’s through bore encoders. But I’d rather not spend $30, especially when the resolution on the through bore encoder is overkill for the scope of my project. The criteria I’m looking to fulfill are:

  • Rated for around 5,000-9,000 RPM
  • Is able to interface with an Arduino (I assume that’s pretty much all 5v encoders)
  • Moderate resolution
  • Cheap

I’m familiar with encoders used in an FRC environment, but not so much with hobbyist encoders. Advice from anyone with more experience in the field of hobbyist electronics would be much appreciated.

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#2

If you’re spinning a wheel you can use a retroreflective sensor and 1 or 2 pieces of tape to create a low resolution encoder.

Also these have come in the KOP in the past: https://www.digikey.com/product-detail/en/cui-devices/AMT103-V/102-1308-ND/827016

3 Likes
#3

What juju_beans said. Or use an optical beam-break like a 3d printer optical endstop and put a disk with a hole/slice in it on your hex shaft. You’ll need slightly fancy coding for a single count per rev solution because what you’re going to measure is the time between rising edges of the pulse rather than counts per second. So you’ll want to put it on an interrupt pin and handle it as an interrupt.

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#4

Thanks for the suggestions, I’ll have to play around with some optical solutions and see what gives the best results.

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#5

If you measure velocity via time between ticks it will be very accurate… Or, at least as accurate as the tick placement. A single tick per rotation will always be 360* from itself.

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#6

Another way to do this would be to use a tiny motor as a generator, and read its output voltage on an analog pin. Not calibrated, but good relative numbers.

#7

I just wanted to also point out that CTR sells a tachometer sensor, if you’re going that route.
http://www.ctr-electronics.com/talon-tach-tachometer-new-limit-switch.html
It works natively with Talon SRX, but it has a 3 pin header that gives you the digital signal from the optical sensor that you can use trivially with Arduino.

#8

I ordered some hall effect sensors. Based upon my research, I think they’ll do the job just fine. I’ll report back on the success or failure of these sensors for those interested.

#9

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