Hi The absolute voltages read are not an issue because you are looking for relative changes. Still, the resistors and capacitors on the patch field need to have tight tolerences to get accurate results. The multipliers may be over ranging. These usually only work over a small range of inputs. It might also be that your unit doesn't include the multipliers. Most analog computing functions don't require the nonlinear operation of multipliers and use mostly integrators and adders. Did you look at the page: http://www.comdyna.com/gp6panb.htm#MULT ?? It describes the use of the multiplier. It needs to be used in conjunction with an amplifier and feedback resistor. You might look at the bouncing ball routines for the EC-1. It looks like you should have 8 amplifiers. I think this is enough to do this routine with. I'm not sure if the info for this is on a web page someplace. Dwight