Analog Input - Potentiometer Problems

I recieved some good advice here many moons ago about using a signal conditioner with a pot when creating an analog input. The time has come to build the project, and it seems to be working fine... with one exception.

The pot we decided to use was one from ElectroSensors.com called the Accu-Dial. It includes a digital readout for creating setpoints and other features. It has worked well in other applications for us. The problem is that the pot requires at least 3.9V to power its display, which is drawn from the pot's supply voltage. The signal conditioner does not list a pot supply voltage anywhere in its documentation, but it measures -0.5V. (Not sure about why the negative voltage.) Obviously, this is not enough to power the display.

The whole application works just fine as is, but we are display-less. So my question is, Are there any "tricks" to get more juice from the signal conditioner to power the pot? Of course we could use an HMI, but we would really like to use this particular pot for the reason of interface consistency.

Thank you for any input!

Brad

What signal conditioner are you using???...

beerchug

-Eric

P.S. That Accu-Dial is pretty neat alternative to a turns-counting dial. Thanks for the info

Thanks for your interest Eric,

The signal conditioner is from M-Systems, model M2MS-A-M2

The docs for it can be found at:
http://www2.m-system.co.jp/mssenglish/PDF/EM/M2/emm2ms.pdf

I can't seem to find any information here on what the potentiometer supply voltage is. Perhaps I'm not looking at it correctly. (I am not an electrician, but a CAD drafter by trade.)

Brad

PS. The docs for the Accu-Dial potentiometer can be found here:
http://www.electro-sensors.com/store/images/Accu-Dial Manual Rev A.pdf

The manual doesn't list it, but it's in the SPEC SHEET. <--- LINK
[attachment]
You were correct in your findings... The excitation voltage is listed as 0.5V. The negative voltage you read was just because the meter leads were swapped.

Sorry, but I don't see any way to make the M2MS work with the Accu-Dial. The M2MS is designed to be used with a potentiometer input ONLY, so you don't have other options. You may have better luck using something like an M2VS which has a DC voltage input. You provide your own DC supply (to power the Accu-Dial display) and vary the input to the M2VS with the Accu-Dial.

Give M-System a call and discuss your application... They can probably recommend an appropriate unit that WILL work with your Accu-Dial.

beerchug

-Eric

Thanks Eric,

Good detective work! I was afraid that might be the answer. I guess I'll have to try something else.

Brad