How To Use Low Resistance Potentiometer?

[Airian_007]

Hi,
I have a 20 Ohms potentiometer, don't know the wattage. i want to use it for the ADC input to microcontroller. i have already used but those are like 10k or 5k, they draw very less current. i was wondering if i could directly hook this low resistance POT accros Vcc(5v) and GND, or i have to use some other technique.
thanks.

 

[alec_t]

You should be able to get some idea of the wattage by comparing the physical size of the pot with pot images and size data from catalogues and datasheets. Direct connection would dissipate 1.25W.

 

[Nigel Goodwin]

Hi,
I have a 20 Ohms potentiometer, don't know the wattage. i want to use it for the ADC input to microcontroller. i have already used but those are like 10k or 5k, they draw very less current. i was wondering if i could directly hook this low resistance POT accros Vcc(5v) and GND, or i have to use some other technique.
thanks.

You 'could', but it will take a considerable amount of current (250mA), so it's a REALLY bad idea. As already mentioned, it will dissipate a lot of heat, and probably run very hot - assuming it survives.

Use a proper value pot, or (if it's some kind of specific 'sensor') do it a completely different way that doesn't make it draw lot's of current (an opamp would help).