Scaling A Pots Voltage

Oct 12, 2007 3 Replies

Hi,



I have a motor controller board that uses a 5K pot for speed control/setting.



The problem I have is that my joystick only moves the pot 20% either side of center so I only have 40% of the total range.



Is there anyway to scale this voltage up to the full range? I was thinking about using an amplifier but don't know of one that will increase a voltage above a certain point and decrease it below another.



Can anyone suggest something suitable?



Thanks in advance,



Michael


If the amplifier approach appeals to you, it's simply gain and offset that you need to do the job. See

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for an application note on how to design the amplifier.

An op-amp circuit would be easier to adjust, but there is an old trick used by early R/C model builders back when they had to build their own joysticks: get a wirewound pot and bypass part of the element with silver paint. The paint was a General Cement product intended for repairing printed circuit boards. I suspect that getting it right would take as long as building an op-amp scaler with trimpots for gain and offset.

The brute-force way would be to use two supplies: (View in Courier) . E1 . | . [R1] . | . E2--+ . | . [R2]

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