Hi
I'm designing an amplifier circuit to enable me to analyse the output from a full bridge circuit (this is a load cell on a DC supply) using the ADC of a PIC.
I'm using a INA126 amp with just a +5V supply and have set the ref input to +2.5V using a voltage ref LM336. I've found that it would be good to adjust the ref voltage slightly. The INA126 data sheet and "A Designer’s Guide to Instrumentation Amplifiers" (by Analogue Devices) both suggest using an op-amp with its + input taken from a voltage divider circuit, since this gives a low impedance supply.
My question is, would this arrangement be better than simply using the LM336 as the ref source? The LM336 has an adjustment pin that should give suffcient range and it's data sheet states it has a low impedance (0.2 ohms).
There seem to be a lot of subtleties in using instr amps properly and so I'd be very grateful for any advice (as I've probably missed some crucial details).
Regards Mike
I'm designing an amplifier circuit to enable me to analyse the output from a full bridge circuit (this is a load cell on a DC supply) using the ADC of a PIC.
I'm using a INA126 amp with just a +5V supply and have set the ref input to +2.5V using a voltage ref LM336. I've found that it would be good to adjust the ref voltage slightly. The INA126 data sheet and "A Designer’s Guide to Instrumentation Amplifiers" (by Analogue Devices) both suggest using an op-amp with its + input taken from a voltage divider circuit, since this gives a low impedance supply.
My question is, would this arrangement be better than simply using the LM336 as the ref source? The LM336 has an adjustment pin that should give suffcient range and it's data sheet states it has a low impedance (0.2 ohms).
There seem to be a lot of subtleties in using instr amps properly and so I'd be very grateful for any advice (as I've probably missed some crucial details).
Regards Mike
