Electronic – Linear output voltage using a potentiometer

potentiometer

I would like to use a linear 10K potentiometer to have a variable voltage output between 0 and 5V using a 5V input. The idea is to have the output voltage increase in a linear way as I'm turning the knob.

  • If it's turned 0% I need 0V output.
  • If it's turned 100% open I need 5V output.
  • As I'm turning, I need to have a linear voltage output

If I hook up the left pin of the potentiometer to a 5V power supply and the middle pin to GND via an LED (to avoid a short when there is zero ohm between the 2 pins), I noticed that the output voltage is not linear.

I get high accuracy in the low range (0-2V) and it takes about a 70% turn to reach 2V, leaving only 30% to cover the remaining 5V.

So if I have 10 imaginary positions on my pot, the voltage doesn't jump with 0,5V on each position.

Can something like this be achieved with a 5V power supply ? And if not, what would be the simplest way to do it ?

Best Answer

Put 5V on one outer pin and 0V on the other outer pin. The middle pin (the wiper) gives you what you want.

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Now this only works when you draw no current from the output so, if you wish to have a circuit that can provide a few mA for a load you'll need to buffer the wiper connection (say) with an op-amp.

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