Faders >100mm??

[Jidis]

I was wondering about that the other day (why the 100mm seems to be the standard "long throw" fader). Seems to be a variety of short ones out there, besides the usual 60. Wouldn't mind a single "foot long" fader for writing automation once in a while, maybe with a big Frankenstein handle like those old desks you see in Abbey Road pictures. ;D

[JMS]

if you got some krafting skills and a few chunks of material and two springs you could make this.  i smiled when i read about your FRANKENFADER idea and it inspired this design using a potentiometer.  i am gonna draw this up in cad with real dimensions i think and build 1 or a few for my midibox project... 

i know it looks like a 3 year old drew this but i did it in 3 minutes with the pencil tool and paintbrush tool for fill in gimp at a crappy resolution.  it's only a rough idea.. the 3d cad is where i make it look sexy.

thanks for the inspiration, awesome idea ;)!   

[/tilted/]

I like this frankenpot!!

You'd need to use some cogs or levers though, to get as much physical travel as possible out of the pot.

failing this, you could perhaps apply a voltage offset and gain using an op-amp.

otherwise you'll need to use scaling, which leads to reduced resolution.

I have a funny feeling the 'abbey road' version would more likely be multi-position switches, though I could be way off here.

[JMS]

I like this frankenpot!!

You'd need to use some cogs or levers though, to get as much physical travel as possible out of the pot.

failing this, you could perhaps apply a voltage offset and gain using an op-amp.

otherwise you'll need to use scaling, which leads to reduced resolution.

I have a funny feeling the 'abbey road' version would more likely be multi-position switches, though I could be way off here.

... there is some pots that only have limited travel with full range i believe.  i should look into this... 90 degrees would be do-able with zero at 45 or zero at zero.  this type of design would work with rotary multi-switches as well.  the hole through whatever panel it's mounted behind can be just like a fader slot.

[Jidis]

I like this frankenpot!!

As do I. :) Hope we get to see it on something. It's so obvious and simplistic, you wonder why there isn't already one out there. It's sort of like those long plastic extension arms you find in stuff, and follow them inside to find them hooked around a little PCB slide switch on the board.

But there is no such thing as an "extra long" regular fader is there?

Take Care,

George

I have a funny feeling the 'abbey road' version would more likely be multi-position switches

I guess I'm not the only one too cheap to scrape up the money for "Recording the Beatles". ;D Been trying to get my Uncle to buy it since it came out so I could "borrow" it (he's the big Beatles fan).

[ilmenator]

But there is no such thing as an "extra long" regular fader is there?

Probably not, but you could use one of those Spectrasymbol soft pots / membrane strips. Sparkfun has them in 200mm and 500mm length.

Of course, that's not the same as nice, smoothly running mechanical fader  :).

Best regards, ilmenator

[stryd_one]

Mount a roller on rails on top of a spectrasymbol slider....

If you're gonna do that you could just use a chainlink and gears to a pot.

[ilmenator]

...and a gear shift for different fader sensitivities  ;D

[stryd_one]

Oh har har har... FWIW I've seen chainlinks to pots, both geared and just multiturn pots, it's not as complex as you make it sound :)

[JMS]

i made a prototype bracket today at work, brought it home and drilled a hole to mount the pot. in the side, rigged up an arm on it.  i'll be looking into finding some 90 degrees pots soon...  i also went to harbor freight tools right down the street from me and looked for springs, all they had was a 200 pc. kit of a bunch of different springs and i don't need 200 springs right now so i'll just buy 1 or two springs from somewhere online.    i'll take a pic when i get frankenpot-prototype-v2 done!

if anyone is interested in one or two of these maybe i can do a small number production run on them?

[cimo]

hey i ve been looking desperately for 90 degrees pots (actually around 110) for my midi pedal if you can find any let me know

Simone

[JMS]

i was chatting on irc in #electronics (freenode) and someone had a  brilliant idea to make this thing be 0-10k ohms from 0-90 degrees movement...

<chr0n1c> anyone know where to find a potentiometer that only turns 0-90 degrees with a full range of 0-10k ohms ?

<SpeedEvil> chr0n1c: why?

<chr0n1c> SpeedEvil,  special project

<SpeedEvil> chr0n1c: can you use a 33K 270 degree pot?

<avrFreak> chr0n1c: no such thing, COTS

<chr0n1c> i'm sure i have seen one before.. now to find who makes them

<SpeedEvil> chr0n1c: that will be 0-10K for 90 degrees.

<chr0n1c> speedevil, that may be the genius idea i was looking for!

<avrFreak> yeah, speed....you beat me to i t

<chr0n1c> so does anyone make a 0-90 degree pot?  i'll take any value...

<SpeedEvil> It of course has a 23K resistor to teh other pin

<SpeedEvil> A gear is the other option

<avrFreak> chr0n1c:  again, not COTS, not that I have ever seen

<SpeedEvil> chr0n1c: why?

so i guess what the deal is.. pots with less than 200/270 degrees of movement are a special order or custom manufacture kinda thing?  (someone tell me i'm wrong on that and they are very common!)

but uh cimo, there you go!  use a 33k pot?

33,000ohms/270degrees = 122.222ohms per degree   --->  122.222ohms * 90 degrees = 11k

   (so it's more like 82 degrees that we need for the FRANKENPOT built with a 33k pot)

[cimo]

mm maybe it s me that don t understand but what i need is a pot that have 10KR from pin1 to pin3, it useless to have 0-10KR on 90 degrees between pin1-pin2 if pn1-pin3=33KR

[/tilted/]

this could work, but you'd also need to increase the voltage at the end of the pot.

probably to around 15V, if zero is still zero... otherwise +10 / -5, etc...

[cimo]

i fear that not sharing the same GND and supply may cause jittering, what do you think?

[JMS]

mm maybe it s me that don t understand but what i need is a pot that have 10KR from pin1 to pin3, it useless to have 0-10KR on 90 degrees between pin1-pin2 if pn1-pin3=33KR

cut pin 3 off, bend pin 2 away from the board, use a small jumper wire from pin 2 into pin 3's hole on the board?

[/tilted/]

i fear that not sharing the same GND and supply may cause jittering, what do you think?

could do.

make it the +15v version then.

[cimo]

cut pin 3 off, bend pin 2 away from the board, use a small jumper wire from pin 2 into pin 3's hole on the board?

???

ok let s go back ..

i need it for a midi controller, the pedal travels only 100 degrees or so.

10khm are needed between the 5v inputs to Pin3 and GND to pin1 (unless you opt for tilted solution but that s another beast).Pin 3 has to detect the range between GND and 5v.

could do.

make it the +15v version then.

mmm not so sure it won t jitter (btw is "jitter" a verb?)

edit: a bit of "cold" soldering liquid/ conductive glue and a magnifier may do the trick ..

[JMS]

i need it for a midi controller, the pedal travels only 100 degrees or so.

10khm are needed between the 5v inputs to Pin3 and GND to pin1 (unless you opt for tilted solution but that s another beast).Pin 3 has to detect the range between GND and 5v.

ahhh, i see, not so simple. would a dual gang pot fit in the pedal? would pins 1-2 from front half and pins 2-3 of the back half work with pin 2 on the back jumpered to pin 1 of the front?

[cimo]

ahhh, i see, not so simple. would a dual gang pot fit in the pedal? would pins 1-2 from front half and pins 2-3 of the back half work with pin 2 on the back jumpered to pin 1 of the front?

you are really proving me! can you draw it? schems?

[JMS]

if my grey matter imprint is right a single pot is two single variable resistors at 180 degrees of each other and the wiper connects to both traces on the center pin?  the board needs some work, i have yet to figure out the creation of traces. (i need to read more of the help file)  so the board isn't needed anyways but i was playing around trying to understand eagle better and went ahead and tried to do a board.  you might need to swap the rear pins if the voltage readout is backwards.  like move 2 to pin 3 on the back half and pin2 on the back half  to jp3 on the board.

EDIT:  I may be crazy and this won't do what i think it would do... i don't have one laying around to try it out? but hey at least i learned how to use almost everything in eagle.

[stryd_one]

90degree pots do exist, as do 60 and 45degree pots. I'm holding some in my hand. Search harder.

[cimo]

@cronic: i see you use a lot of open source programs, why don  t you jump on the Kicad bandwagon?

@Stryd: cmon! the world is not the forum!

[stryd_one]

Sorry for the brevity - I was at work so I couldn't post much, but I didn't want you guys to waste too much time reinventing the wheel ;)

I can't read the part number on these, but they're definitely bourns precision pots. As per my previous tip, joysticks usually use 90/60/45degree throw pots, so that's your starting point....

[cimo]

I can't read the part number on these, but they're definitely bourns precision pots. As per my previous tip, joysticks usually use 90/60/45degree throw pots, so that's your starting point....

mmm sweet and smart