Patent ID: 7061255

Claim:
A system for monitoring corrosion in metal, comprising: a test sample exposed to a corrosion causing environment and a reference sample exposed to a protected environment; an AC voltage source adapted to generate a square wave signal oscillating between ground and voltage Vcc; a filter positioned to receive said signal and filter said signal to produce a sine wave with no second harmonic component; a voltage-driven current source and inverting amplifier adapted to receive said sine wave and produce a current referenced to 0.5 Vcc to provide an AC current from the drive voltage driven sinusoidally and symmetrically above and below 0.5 Vcc; a transformer for receiving said AC current and stepping up said AC current and thereafter transmit said stepped up current through said test sample and said reference sample in series connection; and an amplifier for amplifying AC voltage that is the result of said AC current and respective resistances of test sample and said reference sample to provide a test output and a reference output voltage in a ratio representing the degree of corrosion of said reference sample.