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Where would I find a pot (rheostat?) to replace the twist control ina joystick?

Discussion in 'Electronic Repair' started by [email protected], Sep 27, 2012.

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  1. Guest

    Took apart a Logitech Wingman Extreme Digital 3D joystick to see if I coulddo anything about the responsiveness of the yaw/twist control.

    The piece that controls this is a pot or rheostat (please advise of the correct name) - the axis of the piece mounts to a center rod inside the joystick handle, has a nib on one end that fits into a slot in the handle structure that's responsible for rotating the piece. It seems that it only ever sees a small portion of its potential travel - wondering if I can find one that has a "quicker" response - i.e. will change the voltage more with less twist.

    Any idea where to get pieces like this might be a match or close enough to be retrofitted?

    Thanks.
     
  2. Guest

    NO !

    A potentiometer is specifically referring to a three terminal device, whichis a variable resistor. In most cases the leftermost terminal is grounded,and the input usually goes to the right terminal. The output is taken off the wiper (center terminal). In some low power applications they apply the input to the wiper because of the impedances involved (such as an electric guitar) , but if you do it that way with a buffered signal you need resistance to make sure you don't burn up the bottom end (near the left terminal).

    A rheostat by definition is only a variable resistor, it only uses two terminals. It will have three terminals usually but the crux of the matter is that only two are used in the circuit in question. It can also go either way, with resistance increasing or decreasing with clockwise rotation. They are rarely used in apps with active devices.

    There are diferent curves for each, linear, log or audio, and each has it'sspecific application(s) in a given circuit, depending on what you need. Inold planetariuums (like 1960s) the lights were frequently fed by rheostatswith a logrythmic taper. In your audio equipment, they are almost always potentiometers, although there are a few exceptions inside like sometimes the bias control. What the user sees are pots. Rarely maybe a variable loudness contour control (on really expensive stuff) might be a rheostat.

    But in that application it is the same part, but only with two terminals used. Another application where a rheostat was used is in the dashlights of vehicles for dimming. They have been replaced of course by switched mode controllers in the newer cars because of efficiency. Those are most likely controled by a pot rather than a theostat, but that's because they are feedinga transistor circuit.

    J
     
  3. Guest

    Oops, forgot about the OP.

    Does the thing have three wires or two ? What's more some of these have special mounting and all that. What's needed is a picture. It's possible Digikey has something, but not very probable.

    There are places on the net that carry parts for these things, however if it is not defective and you just want to change the "parameters" so to speak, that's a different story. Maybe if it is just a rheostat (two wires) the range can be changed by just changuing the resistive element. This is not all that likely.

    To change the range, it's better to look for a series resistor off the rheostat and just change that to a lower value. If it is being used as a pot itis a little bit trickier, but can be done.

    We need the wires counted and a picture, plus a full model number so that maybe there is a print or something on the net.

    J
     
  4. .... and any useful quoting.
     
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