Guide Homebrew USB Knob

[jpaturzo]

This guide is to illustrate how to make your own "Knob", very similar to the Griffin Powermate, as seen HERE

Now, the knob I showcase HERE lacks some of the features, but mine can be built out of parts you have laying around the house. Mine didn’t cost me a penny, unless you want to count about $.02 worth of solder.



WARNING
If anything screws up or asplodes due to my directions, I take no fault.

Note
I'm not going into extreme depth in this guide, for a few reasons. The major one is I want people to adapt my method to different objects, not just the video head I used. It's a pretty simple mod, and I can see people adapting it to many things, so I don't want to lock people in to my idea. So in short, go nuts, mod crazy.


Mod Ingredients
Soldering Iron
Screwdrivers
X-acto knife / sharp stabby thing / prison shiv
Old USB optical mouse w/ scroll wheel (could use a PS/2 but I'll cover that later)
Some hook up wire
Video head from an old VCR (or any other suitable knob)


Step One
Plug your mouse to be modded in and make sure it works. This sounds trivial, but you need to make sure your computer doesn't crap on itself with 2 mice plugged in. A friend had this problem, though he did mange to cure it. How he did that, he hasn’t told me yet.

Step Two
Take apart the mouse. The point of interest is the encoder that the mouse wheel drives.

The encoder is at the top of the pic, next to the left button micro switch. Now your mouse may be different, and if you’re using a PS/2 mouse its almost for sure different.

Step Three
De-solder the encoder from the circuit board. Make sure you keep track of what pin is which. Solder extension wires from the circuit board to the encoder. I made mine about 5 inches long, so the encoder can clear the board pretty well.

Step Four
Time to salvage a knob. Mine comes courtesy of an old VCR that had a penchant for eating porno. Its the video head, which is easy to locate when you open up a VCR, considering its the only giant chrome knob looking thing in there.

Here she is. The great thing about the video head is that it’s split in half. One half rotates while the base is stationary. The little bit of shaft you see in this pic extends all the way through the base and is driven by the spinning part. It’s this shaft that is used to turn the encoder.

Step Five
The actual scroll wheel is used here since its what drove the encoder. I trimmed some plastic off the wheel so I had a flat surface to glue onto the shaft. I also ditched the rubber off the wheel since its not really needed.

Take some time and make sure its centered, so when you give the knob a hard spin, its not wobbling all over the place.

I glued it in place using Loctite 495. Its pretty close to regular cyanacrolyte, but cures super quick.

Step Six
Mount the encoder to the knob. I took care of this part by bending up a little bracket out of an old PCI slot cover. The idea is just to hold the encoder in place at the end of the shaft. For this part I used hot glue, but in a more permanent install, I would use the Loctite again.

As a side note, you can see the die cast Al base the knob bolts to.


This way as the knob spins, the encoder housing is static, but the encoder's wheel is being spun. This in turn lets you scroll through documents / play lists at an incredible rate.

PS/2 Notes
In my USB optical mouse, the wheel drives the encoder directly. In a PS/2 mouse, the wheel is attached to a slotted disc, which is an optical encoder, like this ONE . On one side there is a infrared led, on the other a phototransistor. You can use that kind of device, but instead of removing the encoder from the board, you need to de-solder the led and phototransistor and mount them adjacent to the slotted encoder which gets glued to the shaft. It should work the same, but would be a little more complex than my set up. For reference I'm using a cheap Labtec USB mouse

Conclusion
Plug it in and BAM, let USB work its magic. I can now scroll through my 4000 song winamp playlist in two spins.

The first pic in the post is the "finished" product. Right now I have it set up just as proof that I can make this thing work and it will eventually be packaged into my juke box PC case as a shuffle / volume knob. Visionism had the great idea of modding it into a keyboard, which I'd love to see the results of.

Adding LED's, a Plexiglas cover, and a nicer mounting plate are next on the list of things to do. Like I said, be creative with this one, there are tons of things you can use to control the encoder.

Any specific questions, feel free to ask, I know I probably left out something. I’m out of practice writing instructions, which is sad

[dubya01]

Looks interesting! I'll try this with my mp3 server/player, if I can find a broken VCR, or any other knob head.

[Captain Slug]

You could do something similar with a USB gamepad that has analog stick and some form of assignment software. You wouldn't end up with a cool knob though...

[Nath]

Very good mod mate, will definitely be using this in my next project.

[KelticFox]

I have something similar, but I use my XBox pad

[TheAnimus]

A standard rotery encoder can be in place of some mice wheels, it can also be easily hooked up to an rs-232 (COM) port. But then u have to worry about software to drive it.

[H311R4153R]

That looks good , maybe I'll build it into my mediacenter pc.

[GlassX]

I tore apart my old logitech optical mouse, by the wheel works differently. there is a light emitter which shoots a beam through the wheel, which has holes in it, and a receiver picks up the flicker on the other side

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So you cant "attach" a big wheel to the the encoder as such.

[deiol]

well at least now i have a reason for keeping that broken vcd around for 2 years... i can't throw ANY electronics away, i have a problem.

[Murdoc]

Originally Posted by GlassX

I tore apart my old logitech optical mouse, by the wheel works differently. there is a light emitter which shoots a beam through the wheel, which has holes in it, and a receiver picks up the flicker on the other side

     ()
[>]  () [<]
     ()

So you cant "attach" a big wheel to the the encoder as such.

Attach the mouse wheel to a big knob just make a piece of plastic to void the gap and glue it down, it should work.

'doc

[tom61]

Another source of knobs:
Old dead HDs. Remove the top, remove the plates and in most drives you end up with an interesting little knob that spins easily. YMMV, as the guts inside HD vary.

[Ghlargh]

I think these constructions have way too few steps per rotation, i would much rather use the optical sensor for the ball and have a gear or belt from the knob to get the correct sensitivity.

This can allso be used for the optical wheel, you just need to remove the little ball or tab that creates the steps.

Your observation about PS/2 and USB mice is dead wrong btw. Generally, epxensive mice have the optical sensor for the wheel, the cheap ones have the electrical sensor. The electrical sensor, the one that you use, has way shorter lifetime than an optical sensor wich, if cleaned, will not stop working until you wear down the wheel axel.

Originally Posted by tom61

Another source of knobs:
Old dead HDs. Remove the top, remove the plates and in most drives you end up with an interesting little knob that spins easily. YMMV, as the guts inside HD vary.

That's the spindle motor, the problem is that you cannot detect movement if you spin it too slowly.

[tom61]

Originally Posted by Ghlargh

That's the spindle motor, the problem is that you cannot detect movement if you spin it too slowly.

What do you mean? If you connect the encoder or encoder disc (if you're using an optical instead of clicky scroll) directly to the spinning part, it should be able to register any rotation equal to one click or one pass of a encoder spade. Most harddrives I've come across have a hole in the bottom connected to the spindle, glue the encoder wheel into that and you don't need any gears or pulleys.

[Ghlargh]

Originally Posted by tom61

What do you mean? If you connect the encoder or encoder disc (if you're using an optical instead of clicky scroll) directly to the spinning part, it should be able to register any rotation equal to one click or one pass of a encoder spade. Most harddrives I've come across have a hole in the bottom connected to the spindle, glue the encoder wheel into that and you don't need any gears or pulleys.

I have never ever seen a spindle motor with a rotating axel at the bottom, the axel is usually fixed to the bottom, and the "knob" is fitted to the outside of the axel on 2 ball bearings, unless you have a new drive, then there are other types of bearings too.

[tom61]

How many drives have you taken apart? I've only taken apart a few, but most had either a through hole, or the spindle mounted to a larger flywheel with what bolted to the HD chassis in between them. (spin as one, and a screw in the center of the flywheel)

Come to think of it, most of the ones I saw online were for a simular mod, except to one of the old-style ball mouse's axis encoder instead of a scroll wheel, so one's that didn't fit the use probably weren't posted.

I wonder what 'most' HDs are really like inside. So many different brands and varieties, you'd have to get a very big sample to say with certainty.

[Ghlargh]

Originally Posted by tom61

How many drives have you taken apart? I've only taken apart a few, but most had either a through hole, or the spindle mounted to a larger flywheel with what bolted to the HD chassis in between them. (spin as one, and a screw in the center of the flywheel)

Come to think of it, most of the ones I saw online were for a simular mod, except to one of the old-style ball mouse's axis encoder instead of a scroll wheel, so one's that didn't fit the use probably weren't posted.

I wonder what 'most' HDs are really like inside. So many different brands and varieties, you'd have to get a very big sample to say with certainty.

Yup, i have opened a bunch of harddrives. First off, every drive i have opened excepf for some really old ones, have motors made by either of 2 companies, Nidec and Sankyo.
Second, they all have a center axel, but it is fixed to the base of the drive, the only thing spinning is the center mount for the platters. The motor itself is mostly a Y-coupled 3 Phase motor.

[foxx]

YAY, I just made my own. It was originaly made from a hdd cd thingy but then I just made it with a normal cd-r(well 2 acualy.) I used the mouses circuite board as the base and some metal I found. And I glued it all together with hot glue.
On with teh pics.
The finished usbn,(usb-nob)

Without the cd.

The cd by its self, from the side. The white thing is a milk carton lid for grip.

The whole thing from side.

Now you were wondering, Whats the red led? IT GLOWS!!


THis was probibly one of my favorit mods cause of the weird things I used to make it(see above).This one also acualy works.


Now I am wondering how do you get it to control your pc's volume????

[theshadow27]

Originally Posted by jpaturzo

This guide is to illustrate how to make your own "Knob", very similar to the Griffin Powermate, as seen HERE

very very nice. got me thinking! which is hard to do. mod on!!!

[jpaturzo]

That looks pretty sweet Foxx, thats a pretty cool Idea. After using my knob for a while now, I hate not using it. It makes zooming around in Solidworks and Autocad much more fun.

[advance]

I think i saw this on hackaday a while back..