Three-position potentiometer or toggle switch?
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  1. #1
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    Default Three-position potentiometer or toggle switch?

    So I'm getting back to my mod project that I had to put off for my wedding and the start of my new job (oh life...), and I've been wondering what to do with the crossfader which I never use. I've dabbled with some mode settings with it and that's how I intend to map it on my controller, but there have been times where I've accidentally knocked it and thrown my mix into a freefall.

    So my thought is to replace the crossfader with a potentiometer with three detents or three-position toggle switch that sends three midi messages:

    0--------127
    (x---o---o) = no modifier
    (o---x---o) = modifier 1
    (o---o---x) = modifier 2

    (or something along those lines...)

    Am I going about this correctly? The ideal solution would be the toggle switch--it would give me a clear indicator of which mode I'm in. I know that most three-position toggle switches are on-off-on momentary digital switches but I figured I'd ask anyway.

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  3. #3
    Tech Wizard suit's Avatar
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    You should look into a rotary switch. They come as 3 to 8 pole switches and will work really well for what you want to do. But I'm not sure how you would go changing the crossfaders analogue signal to digital to make the switch work.
    Hope it's some food for thought.

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    Quote Originally Posted by suit View Post
    You should look into a rotary switch. They come as 3 to 8 pole switches and will work really well for what you want to do. But I'm not sure how you would go changing the crossfaders analogue signal to digital to make the switch work.
    Hope it's some food for thought.
    Thanks for the input! I will look into it over the weekend.

    So far, I found a three-way toggle switch which is an on-on-on switch but it has 12 terminals. That would be difficult to wire up to an analog input for a crossfader.


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    Threadsurrection

    I am looking into this again and somebody seems to have done some of the legwork for me albeit for a different application...

    http://www.rcgroups.com/forums/showthread.php?t=1329364

    So if I use this SPDT switch



    source

    and wire it to an analog input, ideally I'd have 0v, 2.5v, and 5v at each position of the switch which means I will get midi cc 0, 64, and 127. If mapped correctly this can be pretty useful.

    Let's say I map it for headphone cue selection... at 0 deck A is in cue, at 127 deck B is in cue, and at 64 both are off. That's kind of exciting to me

    If anyone cares to help and can let me know how close I am on this I would apreciate it!

  6. #6
    Tech Mentor derschaich's Avatar
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    for as far as i know most pots have three inputs. how would your wiring look like exactly?

    from what i understood you'd rather get 0 - 0 - 127 wich is not that helpful...

    try it out, and report!

    maybe you would want to use different resistors for the different switch positions to emulate different fader positions. for a 10kOhm fader those would be 10KOhm for 127, 5KOhm for 64, and none for 0.
    give it a shot, resistors are a cheapo!

    edit: oops, saw the wiring sceme further down the threat in your link...

  7. #7
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    Hmm, ok I should give this more thought. The thread said

    You just connect the three wires that were connected to the pot to the new switch the same way, making sure that the wire that was on the center terminal of the pot goes to the center terminal of the switch. The switch will toggle between full left deflection and full right deflection.
    He's saying if my pot looks like this



    and my switch looked like this



    wires 1, 2, 3 on my pot would go to 1, 2, 3 on my switch. Is this wrong?

    On a pot 1 is GND, 2 is OUT, 3 is IN

    What are they on a switch? I'm not as familiar with them...



    So by this diagram, is COM the GND? And L1, L2 input and output?

  8. #8

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    Just swap it for a rotary potentiometer, or if bumping it is really that big of a problem (pick your knuckles up, you gorilla!! ;P) then put some tape over it. The way a switch works is completely different from the way a pot works, you will not be able to simply switch one for the other.

    The pin on the IC that linear and rotary potentiometers are connected to are designed for analogue input. Without the datasheets for the individual components, I don't believe there's any way to tell if it will function properly and safely with a switch.

    Never mind the fact that you would have to reprogram the firmware to follow the change of input...

  9. #9
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    Quote Originally Posted by FreebirdRising View Post
    Just swap it for a rotary potentiometer, or if bumping it is really that big of a problem (pick your knuckles up, you gorilla!! ;P) then put some tape over it. The way a switch works is completely different from the way a pot works, you will not be able to simply switch one for the other.

    The pin on the IC that linear and rotary potentiometers are connected to are designed for analogue input. Without the datasheets for the individual components, I don't believe there's any way to tell if it will function properly and safely with a switch.

    Never mind the fact that you would have to reprogram the firmware to follow the change of input...
    Haha thanks. It's tough to make sense of all the info out there when you don't have much experience with it.

  10. #10

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    No worries. I'm trying to build a custom controller, so I'm learning all this stuff right now, myself.

    I should probably point out that you probably can't just switch the fader with any ole rotary pot and expect it to work for a couple reasons...

    First; what exactly are you trying to change the fader on? A digital or an analog device?
    If it's an analog device, you need to get a rotary fader, because a true crossfader essentially is two opposing pots in one device - when you turn one down, the other one is going up. See if you can find a repair manual for the device so you can get a rotary knob that has the same specs as the fader.

    If it's a digital device, you **POSSIBLY** can just use a simple pot - though again, check the spec's. The problem with both of these is that cross-faders are often built to take a beating, so finding something with comparable specs may be expensive (especially buying a single unit instead of bulk, like a manufacturer can).

    If I were you, I would simply consider putting some rubber, or anything that can increase friction, on the underside of the knob so that it takes even just a little more force to move.

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