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Topic: Small potentiometer range to give full 0-5V? (Read 2 times) previous topic - next topic

Grumpy_Mike


MaxHeadroom

Thanks guys for the replies sofar.

@Grumpy_Mike: Not sure what other vital information I'm with holding :) I just don't have spare pins and want to stick to using the analog input. Another consideration is that encoders needs to be reset every time to find reference and the absolute one might be low cost, bust still expensive in time spend building and setting it up.

@silverxxx: You right about wanting to swing to close to the supply rails and use a low supply voltage. I remember something that the output becomes too erratic?

hmmm :) I've been looking for  a solution for this for a while now. Looks like I then have to either get an actuator made for this, or go the mechanical way of increasing the travel of the pot.
Another idea I'm working on is using a slider pot, it has a shorter travel.

Nick Gammon

Your original figures give you quite a bit of precision (1 in 152). Is that not enough?

MaxHeadroom

#13
Jan 29, 2013, 11:19 am Last Edit: Jan 29, 2013, 11:33 am by MaxHeadroom Reason: 1

Your original figures give you quite a bit of precision (1 in 152). Is that not enough?

Consider that this is a forward backward control with center off, so in fact I have then only 0-76 each way.
Then, I set some dead band around the center, reducing it even more.
I also have a quick calibrate function for the maximum ends where I store the center point and maximums in EEPROM, this must be within the range.
There must also be some leeway for the center point calibration.

It is getting a bit skinny now :)

Only then do I
Code: [Select]
int speed = map(potValue, centre+deadBand, maxTravel, minSpeed, maxSpeed)  for forward speed and Speed is within 0-255 for the PWM

fungus

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

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