Potentiometer value

[adrianvon]

Hello,

Is the wirewound potentiometer in the link below good for position sensing? Does the value matter? (since the only available value is 500ohms)

**broken link removed**

Thanks.

 

[cuza]

In which application you want yo use this potentiometer? The value is important depends by application

 

[adrianvon]

The potentiometer will be used to monitor a motor position. The wiper of the potentiometer will be connected to the ADC of a microcontroller.

 

[alec_t]

Provided your motor shaft position is within 285 degrees and doesn't change frequently that pot should be ok, but a proper shaft encoder would be more durable.

 

[adrianvon]

What effect can the potentiometer value have no the position sensing please?

 

[alec_t]

That depends on what circuit you will use it in.

 

[adrianvon]

The potentiometer will be connected directly to the ADC.

 

[alec_t]

You will have to supply the pot with a stable voltage between its two end terminals if you are using it as a potential divider rather than a simple rheostat. What voltage will you be using? The micro's Vdd, or a port output (the port would have to be able to source >10mA safely if Vdd=5V), or some external supply via a dropper resistor or regulator?

 

[Dean Huster]

For a motor with constant rotation, high-speed rotation and/or rotation in excess of about 350°, your standard pot will never hold up. I'd give it no more than 24 hours of operation before something craps out. I agree with with Alec that a shaft encoder would be the way to go. It's already digital, so there's no need for an ADC; it's in Grey code, so there's no ambiguity in positioning; it can handle any speed, depending on which encoder you buy. You can roll your own encoder with a good drafting program like AutoCAD, providing as many bits of resolution as required. And making your own can eliminate any shafts within a bushing that will limit rotational speed and MTBF, as there will be little-to-no frictional losses. The most difficult part would be machining your own optical pickup bar, but that can be a fun project in itself!