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For my project, I need a rotary encoder. The first requirement for it is to be cheap, and I am not sure how to even start looking for them. The RLS magnetic encoders seem cool, but they are a bit more expensive than I would expect.

The supported speed should be 5000 rpm, which should not be a problem for any encoder.

In terms of resolution, it should best be a sine/cosine output, 256 or so cycles. It could be 100 or 1000; it doesn't matter much.

Unfortunately, I am not even sure which technology is the cheapest nowadays.

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In the past whenever I needed a rotary encoder, I took apart a computer mouse. I do not know if they will meet your requirements, but there's nothing cheaper.

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  • $\begingroup$ the geometry is different. but it's brilliant, might work for another project :) $\endgroup$ Commented Aug 6, 2021 at 3:36
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It's unclear to me what you consider "expensive", but then you are not even asking for a specific device recommendation, but just how to get started.

When I want to see what's available (often even not knowing exactly how the device or item I want is called), I don't hesitate but proceed straight to your usual scumbags - Amazon, AliExpress, ebay. A quick search usually brings up broad categories and more search words.

Secondly, I might go to more specialized vendors like Conrad (popular in Germany - probably similar to Mouser or something like that in the U.S.), but for whatever reason their search functions usually are not as forgiving as the ones from the Big Ones. They have the benefit of having better categories though, so you can drill down along functional requirements if you really do not know good search terms.

In this particular case, I find offerings starting at 2-3 EUR (encoders for manual use; i.e. control knobs - the ultra-cheap kind which basically comes without specs) to 15 EUR (rotary hand wheels as used in CNC machines, specified to 5000+ rpm) to 30+ EUR (dedicated devices looking like a motor, just in inverse).

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You could use a potenciometer (some are even less than 1 dolar) without the stopper preferible with multiple revolutions (logarithmic behavior could improve the final resolution), then with some circuite or in the microcontroller code you could configure it to map each potenciometer revolution (or value) to a motor revolution.

If your motor has 5000 rpm and let +-1rpm of tolerance i think could be a cheap solution.

although there are some encoders around 1 dolar, on internet they could cost at least 5\$ because of shipping/delivery, but if you look in a local store it should cost around 1\$.

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  • $\begingroup$ Where do you find such cheap encoders? $\endgroup$ Commented Aug 9, 2021 at 0:47
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    $\begingroup$ @GregoryKornblum i am from Colombia so the shop where usually get when need some electronic component is didacticaselectronicas , e.g: encoder1 cost around 0.66usd as reference they are only comercial so, import components. $\endgroup$ Commented Aug 9, 2021 at 0:56
  • $\begingroup$ Thanks, I'll check it out $\endgroup$ Commented Aug 9, 2021 at 1:44
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The cheapest option would be a digital hall effect sensor, and a wheel with 1 or more magnets on it. Or optical and a slotted disk if that's easier. See if you can make the design work with that before moving to a more expensive solution.

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