Oh dear, I guess I need to disclose my disreputable purpose!
It's a cold fusion experiment. DC codeposition of palladium and deuterium from a solution of Pd(Cl2) and LiCl in D2O has been shown to produce anomalous excess heat, but it consumes large quantities of palladium, so the deposition has to eventually end to recycle the precious metal. I'm trying to use alternating current between graphite electrodes to first deposit a thin layer of Pd(Dx) on one electrode, then strip it from that electrode while depositing it on the other. There is so much capacitance in the circuit that at higher frequencies I'm just heating the electrolyte without actually depositing any material. So I calibrate my calorimeter with a sine wave at 1 kHz, where there is no deposition, then lower the frequency until I observe evolution of D2 and O2 gasses, which usually accompany metal deposition. With my setup, I need to go below 5 Hz to see gas evolution. My Fosi audio amp is only rated down to 10 Hz, but I can push it as low as 1 Hz. However, I think I'll need to go as low as 0.1 Hz.
The instrument that allows me to obtain accurate current, voltage, and power measurements over a wide range of frequencies is the "Joulescope." Until I discovered it, I was flying blind and actually embarrassed myself when I announced a false measurement of excess heat. (I discovered my mistake when I did a control experiment, substituting H2O for D2O, and got the same result). You can't just measure current and voltage with "true rms" meters and multiply them together, because the capacitance introduces a phase difference between them. The Joulescope actually shows the excursion into negative power when the electrolytic double-layer unloads and returns its energy to the circuit.
- Tracy