What kind of Potentiometer to use on a Casio Sk-1

[pbdlugoss]

I was given a 100K Potentiometer to use with a Circuit Bending project I'm doing. I tried using it for Pitch bend. When I went to use it, while I did manage to Raise the pitch, I was not able to Lower the pitch. Is there a certain kind of Potentiometer that is supposed to be used for bending a Sk-1? If so, what would be the best one to use?

I remember hearing in the past that 10K Potentiometers are the best, is this true? I cannot seem to find anything on what kind to use.

[Gordonjcp]

No kind of pot is "best".  Some may be right for a particular application.  Try to work out where you're adding this pot, and work out what it's doing.  If you've got it wired in parallel with another resistor, you may be able to add it in series with another lower value resistor in place of the existing one.

[Dylan]

how did you wire the pot? Are you new to bending/electronics? If you only have two wires hooked up to the pot, yes you're only going to get pitch up (if you've only found the pitch up contact). Take the common (middle) wire and connect it to the battery terminals, one of them will give you the pitch down. Just connect that to the lug that doesn't have anything connected to it and wa'la, pitch down.

[pbdlugoss]

which battery terminal would suit best?

[pbdlugoss]

I meant terminal as in Negative or Positive.

[Gordonjcp]

. Take the common (middle) wire and connect it to the battery terminals, one of them will give you the pitch down. Just connect that to the lug that doesn't have anything connected to it and wa'la, pitch down.

... or a dead keyboard.  Just slapping the battery voltage across a particular pin isn't necessarily going to give you a pitch-bend control, because you don't necessarily know what that pin is doing!

This is the trouble with the "anti-theory" idea - it leads to huge piles of knackered equipment.  Don't do it.  Learn some electronics and *then* get stuck in, once you can figure out roughly how to do what you're trying to achieve.

[jamiewoody]

ditto the remark about no potentiometer is best. here is my advice...

go to bgmicro, and buy a variety of different pots, 1m, 500k (a widley used one for me), 100k, 1k, and so on. you should score these for around a buck a piece.

then hook solder a wire to the mid pin and either left or right pin (mid is variable). have one of each with wires soldered to them, and keep them as test pots! i personally do a lot of breadboarding, so i like to use solid core wire, and shorter pieces. the solid core plugs into the breadboard holes for handy prototyping! 

if you are not using the metering method, use your ears, this is a good metod for that!

to cheat a little, the ghazalla schematic for the sk1 shows 2 500k pots (poly and pitch) and a 10k skew dial.

[jamiewoody]

an idea (and i need to take my own advice).

build a simple frame of wood, with a vertical stand. attach a piece of pegboard to it. insert a wide variety of potentiometers (from 1k to 1m and in between), and a couple of switches. have leeds with crock-clips attached to each. do the same with an led or two.

when you come up with a circuit on breadboard, simply use a small jumper wire to clip the pot/switch etc to.

it seems that this would be better than having a bench top full of clutter!