1. ## Leo Bodnar Bu0836x

I am building a new version of my TQ. Have an old one built with Bu0836.

I bought Leo's BU0836x this time.
The linear pots I ordered - 10 ohms - don't have the terminals marked.

How do I determine which is GND and which is the wiper?

I tried doing this with a multimeter but I get 2 different leads giving me wiper behavior.

CPJ

2. ## Re: Leo Bodnar Bu0836x

Hi,
Try to find the two terminals that show NO change in resistance when moving the wiper, then the terminal left over will be the wiper.

Andy

3. ## Re: Leo Bodnar Bu0836x

Did you mean 10 kOhms? 10 Ohms is a bit low...

You need three wires to connect the pot. It is important that wiper is identified and connected to axis input.
The other two wires are +5V and GND but they can be swapped with only effect being axis reversal.

Also, typically you'd have one pin on one end and a pair on the other. Input is one of this pair.

The other way to id pins is to put the slider in the middle position. Measure resistance of possible pin pair combinations. The highest one would be between GND and +5V ( ~10kOhms) so the left over is wiper. Wiper will measure about 50% (~5kOhms) to each GND and +5V.

Does this make sense?

Cheers
Leo

4. ## Re: Leo Bodnar Bu0836x

Originally Posted by ANDYSMITH
Hi,
Try to find the two terminals that show NO change in resistance when moving the wiper, then the terminal left over will be the wiper.

Andy
THANKS! Worked perfectly. Now, i get the mid point of resistance give me mid position on my calibration values...

5. ## Re: Leo Bodnar Bu0836x

Originally Posted by Leo Bodnar
Did you mean 10 kOhms? 10 Ohms is a bit low...

You need three wires to connect the pot. It is important that wiper is identified and connected to axis input.
The other two wires are +5V and GND but they can be swapped with only effect being axis reversal.

Also, typically you'd have one pin on one end and a pair on the other. Input is one of this pair.

The other way to id pins is to put the slider in the middle position. Measure resistance of possible pin pair combinations. The highest one would be between GND and +5V ( ~10kOhms) so the left over is wiper. Wiper will measure about 50% (~5kOhms) to each GND and +5V.

Does this make sense?

Cheers
Leo
Makes absolute sense. Yes 10K was what i meant to write. It worked fine.

While on the topic, would a 100k resistor provide better resolution? Of course, it would also mean more dissipation due to higher resistance.

6. ## Re: Leo Bodnar Bu0836x

hi

no not really. what does matter is the controller card you are hooking up to. an 8 bit card will report 255 steps over the range of the pot, a 10 bit card will report 1024 steps and a 12 bit card (which you have in the BU0836X) is going to give you a whopping 4096 steps.
so, in short the higher the resolution of your card, the more smooth and accurate your input is going to be.
good luck and regards from wales .....

ian

hi Leo