Gday Eric,
Thanks for the LTSpice Models Etc, very helpful, I'll try to load them in, see how I go
.
Although probably not a good Idea, I made up the circuit first on a breadboard to get it all working.
I have a couple of issues, firstly is noise at the output of the INA125, it's about 4mV peak, I'm not really sure how bad that actually is but it can't be good I guess.
As I understand, the breadboard won't help the issue & hopefully a circuit board will help.
When I switch the circuit on I get a reading of -172mV at the INA125 Output, with a 10k load resistor to ground at the output & without it actually.
I was expecting to be a little closer to Zero than this but that is an uneducated guess only.
I weighed a lb out & suspended it from the load cell & it seems to give the 10mV change as required although it is not Zeroed as mentioned.
Even though this is on the breadboard at this stage I would like to get it Zeroed to understand it more, not much good making something when you don't have some idea how it works.
To get it Zeroed I need the Offset Trimming you mentioned, I think?.
I can see figure 2 on the datasheet is for Offset Trimming.
If this is what I require I don't understand the schematic, in particular the V+ & V- inputs on the drawing - Attached.
They show what I believe are current sources on both these inputs & I don't understand?
Also they have
100μA
1/2 REF200.
Not sure about that either.
I have some OP37E Opamps, can I use these instead of the OPA237 shown, or is their a more common opamp I can use that I may have, I don't have a big range of things but may have something suitable.
I may not require this Offset Voltage when it's all connected to the existing digital readout but I would like to give it a go just now.
Thanks