Non contact faders

[tos]

So, I hope that all of you saw Infinium noncontact faders. Nice piece of hardvare and fairly expensive.

How about we make a replic? What most of us have layin' around? Mouses...and even if we dont they are quite inexpensive thiese dayz. I think I've seen some [chinese crap probably] optical ones in computer stores for 3-5 euros. Laughable.

Idea A

for this we would reqire:

• nice gear-wheel binded with the encoder axel of mouse
  
• straight geared line (quite frankly I dont know the english term for this)
  
• And offcourse a fine casing[/ul]
  
  
  
  Idea B
  
  Now here we've got a nice idea but:
  
  • how exactly does the optical mouse works(I'll get my hands on one of thiese one of thiese dayz)
    
  • what chip to use & how to read the values
    
  • And offcourse a fine casing[/ul]
    
    
    Suggestions, "u r nuts", ideas, improovments....
    
  dev-optofader 1.GIF
  

[Wilba]

I researched how optical mice work a while ago and abandoned the idea of using the chip in my spare Microsoft Intellimouse Explorer. If you're interested, this was a cool dissection of one: http://www.theparticle.com/hardware/intellimouse/

There's a chip in it that does both the optical sensing (a tiny CMOS camera) and outputs movements as PS/2 or USB. All optical mice of the new breed (not the old kind that needed a special silvery mouse pad with lines on it) work by capturing a frame through the CMOS sensor (taking a photo) and comparing it to the frame it took last time, and working out where they are common and thus if the mouse has moved and in what direction.

So Idea B won't work for a very simple reason: no matter how nicely textured that surface is, there's no guarantee that moving the fader handle will generate exactly the same number of incremental movement events. The easiest way to describe this is that there's going to be some error between actual movement and sensed movement, due to the resolution of the sensor, the frequency of sensing, the speed of the actual movement, etc. The fader handle will get out of sync with the sensed position and then it becomes useless. Depending on how good the sensor is, and the bit that processes the movement events (a lot of PIC code to do that too!), it might not get out of sync for a long time, BUT there's no nice way to find out the starting state of the fader handle, as you can't measure absolute position, only relative. So it's not that good for a fader, IMHO.

If you used it as a relative movement sensor instead of an absolute position sensor, then it would work fine... i.e. you can turn an optical mouse upside down and use your finger on the sensor like a mini-trackpad.

You should consider something using a phototransistor and LED facing each other, and the fader handle attached to a piece of film that passes between them. The film can be a gradient fill of fully clear to fully black. With the right kind of extra circuitry, you'd get an analog signal that measures absolute position. I think I saw that once on a MIDI controller...

[Screaming_Rabbit]

Suggestions, "u r nuts", ideas, improovments....

... you're nuts  ;D  ;)

The expensive part in a linear fader is not the resistence path... it's the mechanical design! So, using a dual optical interrupter (or even a mechanical encoder) is propably more expensive than a resis. taper.

Greets, Roger

[tos]

Oh, I think I've 4got to mention that thiese part are supposed to be "recycled" from old mouses[mechanical] or cheap mouses[optics].

Anyway, I learbed something new, today, tnx rabbit.

Btw, I'm looking forward to complettion 0f that ps/2 interface

[Skunk]

... you're nuts   

The expensive part in a linear fader is not the resistence path... it's the mechanical design! So, using a dual optical interrupter (or even a mechanical encoder) is propably more expensive than a resis. taper.

Greets, Roger

Right Roger, it doesn't make much sense to invent the weel twice! Look at the motorfaders from ALPS. They are just perfect and deliver an excellent quality for a reasonable price (-> cost-performance issue).

Cheers,

Skunk

[Screaming_Rabbit]

Oh, I think I've 4got to mention that thiese part are supposed to be "recycled" from old mouses[mechanical] or cheap mouses[optics].

Anyway, I learbed something new, today, tnx rabbit.

Btw, I'm looking forward to complettion 0f that ps/2 interface

... for the optical ball-mouse recycle, you don't need a PS/2 interface. You can connect the optical interrupters right away to the DIN board. "Logitec" mices have four pins where of one goes to ground. If I find the pin layout on one (which one  ???) of my computers, i'll send it to you (I have it somewhere). I'll use it in my box for the jogwheel (low mechanical resistence).

Look at the motorfaders from ALPS. They are just perfect and deliver an excellent quality for a reasonable price (-> cost-performance issue).

... right. It's pretty hard to design the housing so the faders are sliding nice and easy. I just received 12 samples of "ALPHA" Motorfaders. They're Chinese copies of the alps (optical aspect) but they don't get close to "ALPS". The "expensive" version (which is a copy of the ALPS K-Type) feels worse than the ALPS N-Type fader.

Greets, Roger

[tos]

Pinout would be nice, tnx in advance. Either way, that PS/2 intercafe will be an interesting thting to toy around [let's see, a trackball instead of 2 encoders; custom, 2xKeyboard...nice bunch of keys]

[DrBunsen]

You should consider something using a phototransistor and LED facing each other, and the fader handle attached to a piece of film that passes between them. The film can be a gradient fill of fully clear to fully black. With the right kind of extra circuitry, you'd get an analog signal that measures absolute position. I think I saw that once on a MIDI controller...

That's a top idea - print out a set of 16 strips on laser printer transparency and cut them out.  My suggestion though - if the film has to move, you need 2x length of the film clearance under the board, for all the way up and down.  Mount the film stationary, and attach the LED/LDR pair to the fader handle.  Probably a little simpler to construct too.

Dust, smoke, fading or aging of the film could be a problem.

Now who's got an idea for a homebrew motorfader?

[Screaming_Rabbit]

Dust, smoke, fading or aging of the film could be a problem.

... who's smoking in the studio? .... except of me ;D :P

Greets, Roger

[Davo]

... who's smoking in the studio? .... except of me ;D :P

Greets, Roger

He must be talking about the smoke wafting from the rack.

;D

Davo

[tos]

Let's not go to much offtopic here, I'm hopeing this tread to be productive.

Laser cutted piece of non transparent plastic. I think that Sasa D. would agree with me.

Question is how to lead signals from encoder if it is moved with handle.

[tos]

I'm a sucker for digital input...hehe.

I found something interesting:

Basics: http://www.societyofrobots.com/sensors_encoder.shtml

The wireing: http://www.societyofrobots.com/schematics_infraredemitdet.shtml

About that film with gradient printed: http://www.societyofrobots.com/schematics_photoresistor.shtml

This would be easy to implement mechanically: http://www.societyofrobots.com/sensors_sharpirrange.shtml

[tos]

It's funny to read a german forum translated via Google.

Now I'm thinking scratch/wind plates with a touchsensor feature.

The commercial would go something like this: "When you lay your hand on it, IT KNOWS!"

[tos]

Sharp distance measuring sensor: GP2D12

minimum/maximum distance: 10/80cm

output, analogue: 3.1-0.6V

Conrad price: 25eur :(

:weep:

[Screaming_Rabbit]

... for the optical ball-mouse recycle, you don't need a PS/2 interface. You can connect the optical interrupters right away to the DIN board. "Logitec" mices have four pins where of one goes to ground. If I find the pin layout on one (which one  ???) of my computers, i'll send it to you (I have it somewhere). I'll use it in my box for the jogwheel (low mechanical resistence).

... I found the pin layout. If you PM me your E-Mail, I'll send it to you. - Anybody else interrested?

Greets, Roger