membrane potentiometers?

[FUZZZZzzzz]

i know a few places to find them, but they're still a little bit expensive to mess around with. anyone with a cheaper source?

http://www.sparkfun.com/products/8607
https://www.sensofoil.com/sensofoilR-products/

[FUZZZZzzzz]

these guys even sell 500mm ones:

http://www.trossenrobotics.com/

[Earthscum]

500mm = 19.7", @$26... that's not bad considering what you could do with it. To me, that's begging to get hooked up to some oscillators and filters.

I'm digging on this one: http://www.trossenrobotics.com/store/p/5604-Softpot-Rotary-Potentiometer.aspx

But, yeah... unless you're buying just one (say, 3 or 4 for sweeping different filters or flangers, etc... hey... finger touch flanging!) these would get expensive quick.

I do remember people making their own resistive paint. If you were to suspend a flexible metal plate a small distance away, you could make your own touch pots, possibly. Basically, look up tactile switches for an idea of "suspending" the metal piece (think, also, stretched out 'slap bracelet'). I have made diy switches in the past using a couple pieces of spring steel seperated by heavy paper (about 1 mm thick, 50mil) on either side. Basically, what I'm thinking is hard strip with resistive material, band of paper on both edges of the strip, super thin (flexible, springy) metal strip laid over. The paper acts like a bridge to keep the metal and resistive materials separate until you push hard enough to make them touch (this is basically how these work... I, regretfully now, tore one apart many years ago to see what was inside, lol).

[FUZZZZzzzz]

yeah.. i know the prices are quite resonable, but knowing myself I would wanna put 5 of them on one box.. but actually I need to order one.. let you guys know if they work well and how durable they really are.. so much to build..

ps. i know there are people building these things themselves.. gonna find out a little more..

[iq01221]

I think it's great! DIY version and market one! Any choice could be a new start, imaginate... smart stomps .

[Gurner]

The downside with membranes is giving visual feedback to the operator  as to where the 'current control' setting is - it's all well & good when your finger is physically on the membrane (ie you can see where the 'control' setting is - it's where your finger sits!), but once your finger is removed....you need to then build in someway of the system remembering & visually representing the last membrane 'finger' position.

The stribe gives you visual feedback .... http://www.soundwidgets.com/stribe/   ...& it undoubtedly looks cool (& I could knock up a clone in an hour or two - it's not complicated ...just repetitive!).....but that's an awful lot of supporting hw (LED drivers, leds) for doing essentially what a pot knob does on its own!

Sometimes things get overengineered!

[soggybag]

I wonder if you could make a flexible wah pedal? Imagine a flexible pad you could press with your foot rather than a mechanical treadle.

[Jazznoise]

These would act as some sort of ribbon controller! Could be good for those wanting a Fuzz Probe workalike or something of equally eccentric nature but avoids that nasty EMF!

I'd seriously consider attaching one or 2 of these to the body of a guitar, possibly wiring them to control tone or volume, or better yet to give it a seperate jack out and let it act as a form of expression pedal!

[Gurner]

I'd seriously consider attaching one or 2 of these to the body of a guitar, possibly wiring them to control tone or volume, or better yet to give it a seperate jack out and let it act as a form of expression pedal!

Again, without some visual feedback, then they're almost useless on a guitar.  How would the guitarist know where the tone control or volume control is presently set? ...to build something that gives the guitarist membrane 'visual feedback' would need something like a microprocessor- not to mention you'd have to make your guitar active to incorporate (with the impact on tone that brings) - then what happens when your battery dies ? "my guitar, it no workee" - which means wiring in a 'just in case' bypass switch...and on & on it goes.

Also you need to bear in mind that these membrane devices don't 'remember' where along the strip you last pressed - so you have to couple the membrane with hardware that notices when there's been a 'change' (finger pressed on the membrane) & then something needs to store that change.

Ideal for synths and the likes where supporting microprocessors abound ...along with plenty of resident power nearby (unlike a guitar)

[Jazznoise]

Visual feedback? It's only needed if visual feedback is what you want! The differences in setting will be heard quite clearly! Setting it up so that the R value was 50% of the Max when the ribbon is untouched would leave very little ambiguity. Or a switch between 0, 50% and 100% default values.

[artifus]

http://www.diystompboxes.com/smfforum/index.php?topic=79126.msg652655#msg652655

http://www.oocities.org/tpe123/folkurban/synthstick/synthstick.html

[Gurner]

Visual feedback? It's only needed if visual feedback is what you want! The differences in setting will be heard quite clearly! Setting it up so that the R value was 50% of the Max when the ribbon is untouched would leave very little ambiguity.

so why do they put indicators stripes on guitar knobs? (yep, because I'd say something like 99.9999% of the guitar owning masses want visual indication of where their control pot is!)

Sound (particularly tone) wrt our hearing, is a relative/adaptive thing ...ie our ears quickly acclimitize to a new sound & then our brain starts treating what we're hearing as the new 'normal' - so while you will hear any change clearly as you make it....within a few minutes, you'll be left wondering (especially if you're concentrating on other stuff in between...like playing the guitar!) that's why we visually need to know what our present settings are on a guitar ....even if it's just a simple stripe on the knob...it shows at an instant to our eyes, if there's a bit more treble that can be rolled off, or a little bit more volume left on tap etc (eg the difference between a bridge and neck pickup is like night & day, but still...how many times do you glance at your 5 way pickup selector switch just for affirmation?)..... or are you just going to press on the membrane and hope you called it right relative to where you think you last pressed it? Seriously, a volume  or tone control pot without a visual indicator, is of little practical use when it comes to humans!.

[MattHW]

I think you're making a lot more out of this 'visual feedback' thing than necessary, of the 3 gitars that i play regularly, 2 have knobs with no visual feedback, and the other has most of its knobs missing, and I don't find myself struggling at all.

On another note, would it be possible to implement some sort of slider with one of these pots, that not only gave visual feedback, but also kept the contact in the right place?

[Gurner]

I think you're making a lot more out of this 'visual feedback' thing than necessary, of the 3 gitars that i play regularly, 2 have knobs with no visual feedback, and the other has most of its knobs missing, and I don't find myself struggling at all.

For use on a guitar you may be underestimating the issue - because with a membrane with no visual indicator, you'll certainly get  unintended 'jumps' in volume/tone if you don't know where your last setting was set (whereas an unmarked guitar pot will smoothly pick up/continue from where it was 'left' when you go to change it)...& wrt using these as an onboard volume/tone there are all the other issues I mentioned (ie detecting the value change, remembering the new value, power)...of course most of these issues can be surmounted relatively easily (PIC anyone?), but that's a fair amount of supporting hardware to replace something that works perfectly already - a simple pot/knob!

[Earthscum]

I kind of get what Gurner is getting at... some of you don't appear to realize that these aren't set and forget. When you take your finger off of the strip, the pot goes back to however you wired it in. These would be good for manual sweeps.

If you put one on your guitar, you could do some volume vibratos by sliding your finger along the strip instead of grabbing the knob, but you would still have to use your knobs for the set and forget.

These probably wouldn't work as good as a tactile switch. If you want, they make tactile switches that lay nearly flat, and could be sammiched between the box and a hard piece of rubber, if you really wanted.

Just think, though... for the NoizeHounds, these are kewl as hell! I kind of want to use 2 strips and make what is basically like the SynthStick (+1 to that thing... saw vids of a couple when I first got into DIY effects). Basically, I was thinking you could run the 2 longest ones on a "neck" (even put tuning pegs pots at the top). They would just run a couple of R.G.'s fake guitar oscillators, and then use piezo pickups to tap on with your "picking" hand (the gold disks make good drum triggers, if you ever wanted to make a Frisbee drum kit). The piezo disks would essentially be used to control the ADSR, just like a drum trigger... be an easy or complicated project, but could be fun.

[Jazznoise]

so why do they put indicators stripes on guitar knobs? (yep, because I'd say something like 99.9999% of the guitar owning masses want visual indication of where their control pot is!)

But I'd want this for me. The 99.99% of guitarists wont actually ever get to play this guitar.

Sound (particularly tone) wrt our hearing, is a relative/adaptive thing ...ie our ears quickly acclimitize to a new sound & then our brain starts treating what we're hearing as the new 'normal' - so while you will hear any change clearly as you make it....within a few minutes, you'll be left wondering (especially if you're concentrating on other stuff in between...like playing the guitar!) that's why we visually need to know what our present settings are on a guitar ....even if it's just a simple stripe on the knob...it shows at an instant to our eyes, if there's a bit more treble that can be rolled off, or a little bit more volume left on tap etc (eg the difference between a bridge and neck pickup is like night & day, but still...how many times do you glance at your 5 way pickup selector switch just for affirmation?)..... or are you just going to press on the membrane and hope you called it right relative to where you think you last pressed it? Seriously, a volume  or tone control pot without a visual indicator, is of little practical use when it comes to humans!.

It is adaptive, yes! But our hearing memory is generally 30 seconds to 2 minutes - which is quite abit. You'd finish a hardcore punk number in that time no bother! If the sonic differences are only noticable from a visual perspective then I'd consider it a waste of time. Might as well be F.O.H engineer that spends 5 minutes twiddling the EQ on the kick drum, realizing he's got it perfect only to realize it's not even engaged. Or the mixing engineer who adds that extra 50hz "beef" to the BeeJee cover band's lead singer.

I'd be intending to use this for volume or modulation parameters - which are generaly very breif and very obvious. More of a spot effect than a constant sound adjustment tool. Anyway, it'd be my guitar! Don't worry!

[Gurner]

Folks, don't get me wrong - I love the idea of using these things....but for the right application.

But when I hear of them being used as substitute volume pots & tone pots for a guitar...the "oh,oh" in my head compels me to chime in - I'm not saying don't do it...but just consider the stuff that you maybe hadn't considered. To me a basic requirement of a guitar volume pot, is 1, to see what it's set at, 2. to have it change smoothly. 3. to have it remember my setting. 4. not need power to work  .....but hey, membranes rock - if nothing else you'll have a great journey dabbling with them.

[PRR]

A $2 pot will hold a setting. These don't.

[deadastronaut]

^ yep, but good for a bit of fun though...i wouldn't mind messing around with one...could be good, especially on synthy/noise stuff....

[Earthscum]

That's what I'm talking about... I wonder how fast these would respond in a circuit to tapping on them. Wobble-bass, finger tapped, would be ultra sick... I sound like such a d-bag right now, lol.