Unfortunately, they aren't cheap. It looks like the two main solutions are...
The Ultimarc SpinTrak - https://www.ultimarc.com/SpinTrak.html
TurboTwist 2 - http://groovygamegear.com/webstore/index.php?main_page=product_info&products_id=268
Both of these products start at $69 USD ( *cough* price collusion *cough* )
There are a bunch of DIY spinner articles that involved ripping apart old mice. The one that really caught my eye involved an old VHS VCR drum head.
I bought a couple old VCRs from the local thrift shop for $10 each. Ripped them apart. Extracted drums. The first one I ripped apart was very different in structure than the Instructables article. I put it aside unsure if I would be able to use it. The second one was similar to the article, so I was pleased.
The article made reference to a DIY circuit board, ripped apart mouse, etc, and I wasn't really keen on this solution.
I had read a few things here and there about the Arduino, and decided to dive in. I wanted to make a quadrature encoder. Here are a bunch of articles that I came across:
One of my personal problems (I blame my ADHD) is that I don't document enough. So I do a bunch of stuff, and then I don't know why I did it.
I had previously done a bunch of reading on all of this, and a couple months ago I ordered the following components.
330 ohm resistors
10k ohm resistors ( I keep accidentally typing resisters)
Arduino Leonardo Pro Micro ATmega32U4 w/ USB header - these things are about $5 CAD on eBay. I don't know if there is a significant difference between the $5 eBay versions and the $20 SparkFun version. We'll see when things start to come together if there are any issues with the cheap Chinese stuff.
So I have all this stuff, plus some other odds and ends I've been ordering off eBay for the past few months, and now I'm at the point where I should be able to start prototyping.
I asked myself if I had enough components. The articles I read above included some additional things like 100, 150, 220, 270, 4.7k, 5.6k, 33k, 470k, ohm resistors, 0.1µF (100nF), 1uF (1000nF), and 10nF capacitors. Do I need these things while working on this project?
Tangent! It's easier to type uF for microfarad, but using a 'u' is not accurate. The proper symbol is 'μ'.
Lowercase letter Mu / Mμ; micro sign or micron
ALT + 230
Option + m on Mac (hmm, maybe it isn't that difficult to type)
Also, ohm - Ω (Mac - Option + Z), unicode U+2126, alt+234. Something, something about Greek Omega -U+038F.
Back on track. Do I need all these extra components while working on this project? It's better to have them on hand than not. I hopped onto Arrow.com, and ordered a bunch of extra pieces. When possible, I splurged and ordered automotive grade components. We are talking about pennies difference here.
Don't worry about ammo vs reel - it's just the way they are packaged in bulk. Exact same components. Lower TCR is better, but not necessary in small projects like this.
To be continued...