Could there be microscopic holes in the plastic allowing the water to make contact with the underlying Al?
Porosity of the teflon is unknown. Conductivity is virtually zero.
Is there an AC ripple on your power supply (or are you using a battery)?
Yeah, about 22 mV ripple on a 9.15 V RMS supply.
Is there a ground connection to the Al tray?
Floating on a formica surface. Terry
