From Technologia Incognita
Jump to: navigation, search

Can I ask why you chose a wheel? Cause, if I understand it correctly, you're not making the 'steering' wheel, but the 'full|half|slow' thing, right ? That is afaik not a wheel, but a handle that moves around a 'solid' circle, totally not like a wheel.
For that part you're better off choosing some sort of cylindrical body, like um, maybe a paint can, food container, anything but a wheel. The handle is harder obviously, for the right look it'd have to be copper/brass. I'm sure browsing through a market in the box of old 'hang- en sluitwerk' you'll find suitable stuff tho. Pity the Waterlooplein market is not what it once was...

The 'stops' might be made by utilizing and old electrical rotary switch, they had notches like that. checking space state with an arduino is simple enough; use a led and photodiode that counts slots in a slotted disc. If you need 100% certainty in which position it is (instead of relative) deploy a pair of leds and photodiodes and encode the slots binary like slot 1 __XX and slot 2 _X_X, that way you have 4 positions. With 3 pairs you have eight.

Ultratux 02:13, 20 November 2012 (CET)

I think the point was that 1) it's metal and 2) it's round, and the project can go from there. Maybe it's a little too narrow, but considering we only need one handle, and that will also add width to the whole construction, I think it's ok.
My only issue is that it's quite over-sized for a typical EOT, but that also has it's comical value.
Btw, why mess with leds and photodiodes when you can just use a rotary-encoder? I do think it would be nice to have LEDs for backlight (maybe different colours to signal something)
Dreamer 14:10, 20 November 2012 (CET)

The photo diode idea comes, I guess, from computer mice when they still had a ball in them instead of a camera. That ball drove an X and an Y axis, and on such an axis was a tiny slotted wheel, which a photo diode +led combo peeked through. We've all opened a mouse at one point I guess. So because that stuff is so easy to get and ubiquitous... I mean, non-optical mice are thrown away by the truckload these days, so... Don't know rotary encoders, but obviously they were uninvented at the time Logitech et al made their first mice, or they have too much friction which in a mouse wouldn't work for obvious reasons...
See nice pics of it here:
Ultratux 01:31, 21 November 2012 (CET)

Well, the idea of a rotary encoder is that each position encodes for a different signal. So you don't have to track where on the wheel you are, you just measure at which position the handle is located. Which is arguably much simpler. [1]
In my project box I have a spare rotary encoder, so we could use that. The only thing is that it has to be situated within the hinge somehow.
I think amx109 already had an idea how to do it though .. lets see if he sees these comments :P
Dreamer 10:22, 21 November 2012 (CET)