PDA

View Full Version : Looking for advice on sensor output processing



shobley
02-06-2010, 05:27 PM
I've been working with a pressure sensor that has a differential output.

It has Vin (9v) Gnd, + out and - out. The range of the sensor output appears to be from 0-0.5v when reading from the (+) and (-) outputs.

Either of these outputs are actually offset by Vin/2 so the output from (-) is 4.5v and the output from (+) varies from 4.5v to 5v.

I'm looking to shift the output so that it runs from 0 to 0.5v in relation to true ground. I only have 0-9v to play with. In theory I should be able to shift the output signal from + down to Gnd using a simple OpAmp setup - but the only way I've done this in the past is with a differential supply.
I thought about splitting the supply with a floating ground, but is there an easy way to do it using the same 0-9v supply I'm using for everything else?

Steve

MikeG
02-06-2010, 07:09 PM
I think you're asking how to drop 4.5V. You could use a POT or a resistor.

What's the name or model of the sensor? What's does your circuit look like... do you have a schematic handy?

Edit: You might want to look into a AC small signal common emitter amplifier.

shobley
02-06-2010, 08:50 PM
Thanks for the reply.

A quick trip to Wikipedia solved it.

I wanted a single op-amp (LM324 in my case) configured as a differential amplifier.

That did the trick. Now I get a nice clean 0-5v signal (I scaled it by 10) from the output.

Steve