After a wander through various web sites covering various more and less common aspects of instrumentation amplifiers I had the following tabs open (plus others related but lee worthy of inclusion). May be of interest to some. (All are no doubt known to gargoyle but some were accessed via links from links from ... . Not all are wonderful but there are a few gems. Potential black hole for some but a fairly specialised one. YMMV Russell http://www.analog.com/library/analogDialogue/archives/34-01/haystack/haysta= ck.pdf http://www.analog.com/en/power-management/power-monitors/ad8557/products/CU= _dh_designers_guide_to_instrumentation_amps/fca.html http://www.analog.com/static/imported-files/application_notes/AN-244.pdf http://www.analog.com/static/imported-files/design_handbooks/58127566743127= 78737Complete_In_Amp.pdf http://www.linear.com/products/instrumentation_amplifiers http://www.linear.com/product/LT1167 http://www.ti.com/lit/an/slyt226/slyt226.pdf http://www.analog.com/en/amplifier-linear-tools/multisim/topic.html . https://www.google.co.nz/search?q=3Dinstrumentation+amplifier&espv=3D2&biw= =3D1807&bih=3D1148&tbm=3Disch&tbo=3Du&source=3Duniv&sa=3DX&ei=3DVMWCVI_rLpa= 48gWJz4LoCw&ved=3D0CCIQsAQ&dpr=3D0.9 http://www.analog.com/static/imported-files/tech_articles/25406877Common.pd= f http://www.ti.com/lsds/ti/amplifiers-linear/instrumentation-amplifier-produ= cts.page .. http://www.microchip.com/ParamChartSearch/chart.aspx?branchID=3D11017&mid= =3D11&lang=3Den .. http://www.analog.com/static/imported-files/tech_articles/55798267SEN5247e.= pdf .. http://en.wikipedia.org/wiki/Instrumentation_amplifier --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .