I am wondering if anyone has any experience to answer this question:
I am looking at the possibility of building
Conrad Hoffman's nullmeter using a dual precision opamp. One side could do rail-splitting, and the other side can do the actual difference multiplication.
However most opamps also ask for say, a couple of 100n caps around their supplies. The problem is that given those caps will then be both loading the output of one opamp, while also being used to stabilise it as a whole, mostly it seems this would produce oscillations from capacitive loading, from what I can see trying to set up the circuits in LTSpice. Also the datasheets tend to warn against that in general as well. This is one advantage of the original component, TLE2426, it is designed to be stable after you add enough bulk capacitance. If interested, I was looking at an
OPA2186 currently, which seemed to have a nice combination of decent uV offset, low current bias, and low noise. So I have some queries-
1. Anyone know if you're likely to see these oscillations in practice, trying to operate mostly a simple DC circuit with seconds of stabilisation time?
2. If operating off some simpleton batteries, like 1x9V or 4xAAs, would it be possible to forgo the capacitors all-together? Would this be likely to ruin performance or noise of the opamp / circuit in use?
3. Or anyone know of a scheme of compensation to allow for this design to work?
If this design can be stabilized you could design a seriously tiny board to implement this instrument.