@ericgibbs
Will get new AD623 soon. When the measure source - and the supply voltage is from the same source then 0.3V over the source is pretty much impossible, or? (This said, I did some test with a 9V battery as bridge source..... so it is possible)
Since I use probes to connect, and since it is very likely that not all probes connect at the same time, and therefore pin 2 and/or 3 can get full +V or GND - but not +V + 0.3 - there is no harm - or? I will put some R in the K range in front of the pin 2 + 3 anyway though.
IC and bridge supply can be from the same source, or?
@alec_t
What is the minimum/maximum V the AD623 can handle on the inputs? I have no "offset-nulling facility". I have the REF (5) to GND. I did see some designs that use a ref voltage IC (i.e.:
http://www.ti.com/product/ref1004-2.5 ) - is that something I should try?
My next plan, after I get the new ICs:
I will make a classic 4 R wheatstone bridge (maybe with 1K resistors)
Will substitute 1 R with a same range Pot
Will put protection R in front in IC pin 2+3
I am not too concerned by the 50Hz interference. Will be hard to avoid on a breadboard design I think.
Any comments so far?
I will try that tonight.
Added: A circuit with an similar INA126 were pin 5 goes to a ref1004
Source/