On 2022-Feb-13, at 9:04 AM, Douglas Taylor via cctalk wrote: > Stopped fooling with the AXV11 for now. Applied various voltages to the Data > Translation input and recorded the A/D octal values to get an idea of what > the calibration of the board is. It looks very linear, +/-10v range. > > Using a single battery and voltage divider I was able to generate voltages on > the input of the DT2762 board, however, I had to swap wires to get negative > voltages. Is it possible to construct a battery driven circuit that will > present both positive and negative voltages at the input? A bridge of some > sort?
You said it: what amounts to a wheatstone bridge. Take say, two 10K R, in series across the battery forming a 1:1-split voltage divider. The center point shall be the common/0V. The wiper of a pot across the battery forming a variable voltage divider presents the +/- test signal. That would give e.g. +/-6V from a 12V battery. It also presumes you have a reasonably high impedance on your target input/load as you need to keep the Rs adequately high to keep from draining the battery. If you wanted to get +/-12V from a 12V battery, or needed a lower impedance source, a couple of op-amps could be worked up into an equivalent circuit. E.g. two unit-followers, one inverting and one non-inverting, both fed, in counter-point, from the fixed divider and the variable divider, 0V from one output, signal from the other output.
