Magnetic Potentiomtres

[George Sephton]

Does anyone know where I can buy a magnetic potentiometre, ie the ones you get on digital sound desks that move by themselves, and if so if they can interfaced with a PICAXE to move by themselves.

Thanks,
George S.

 

[BeanieBots]

The ones I've seen have not actually been potentiometers but were just small stepper motors with an encoder. The stepper is just strong enough to move the encoder but can easily be overridden with a push from a finger.

 

[Andrew Cowan]

http://www.rapidonline.com/Electronic-Components/Resistors-Potentiometer/Control-Potentiometers/Motorised-20k-dual-gang-rotary-potentiometer/78271

As Bb says, just a motor (although this is a rotary one).

A

 

[George Sephton]

I found these, they're motorised which is still good, Im not sure how much they are or where to buy them from but stuff like this is the sort of thing I want:
http://www3.alps.com/WebObjects/catalog.woa/E/HTML/Potentiometer/SlideMixers/RSN/RSN_list.html

George.

 

[Dippy]

They're neat.

The magnets and motors must be very small in those.

Why don't you Google the part number or email Alps?

 

[George Sephton]

Yeah I've emailed alps to see where I can buy them assuming there not really expensive, the alternative being making my own thing with a few cogs etc.

 

[Andrew Cowan]

http://cgi.ebay.com/Alps-Motor-Driven-003K-10KB---Slide-Pot,-10K-Linear_W0QQitemZ180325766702QQcmdZViewItemQQimsxZ20090206?IMSfp=TL090206162007r9156

The ones in your link don't seem to have the motors attached.

A

 

[hippy]

I think you'll find they are quite expensive. They are mainly used in top-end audio mixing or theatre lighting desks where they need to be of high quality and precision, both in terms of potentiometer and positioning - It's no good magically moving the pot back to 'where it was' when that isn't. The mechanics are also a bit more complicated than simply bolting a motor to a pot.

Quite amazing to see them working though.

 

[George Sephton]

Yeah I use our digital sound desk at school that runs whole programs you can set up and watch loads of faders move in time together by themselves, first time I saw it I was amazed. I have decided I will make my own, by attaching a row of teeth to the potentiometer slider knob and a small cog on a motor I can look at the timings and everthing I build an accurate automated slider my self controlled by a PICAXE, the unfortunate thing is that I need 10 of them, laser cutter here I come.

 

[boriz]

You could prolly build your own using hacked servos. You can get the small type, new, for <$5 at Deal Extreme.

 

[George Sephton]

You could prolly build your own using hacked servos. You can get the small type, new, for <$5 at Deal Extreme.

Actually how could I use a servo as I do have one, it's got a wheel and 4 prongs (Im new to these) and it has a red black and white wire, how could I use that to move a slide potentiometer up and down?

 

[George Sephton]

Actually it doesn't have to be a potentiometer it has to be a slide that the PICAXE can read the position of and control if that make life easier.

 

[jglenn]

Mechanical things just break. How about a LED bargraph, and EEPOT, 256 steps. Might be hard to get a 256 LED element, so just use less and approximate. For manual control use an up and a down button. The longer you hold it, the faster it scans. It might fit with all smd I2C output ports chained.

 

[George Sephton]

I was thinking about that, removing the slide aspect all together but that could cause unwanted errors and sliders allow very minor movements.

 

[Andrew Cowan]

Do you wan to manualy adjust the slider?

If so, you need some sort of slipper clutch on your servo.

A

 

[George Sephton]

Ive decided Im going to take a normal potentiometer and build a row of teeth to be controlled by a motor that way I can still move the potentiometer manually and it will then change when the motor starts, and then I'll have to work out the coordinates once Ive built it.