Elapsed time indicator and electrolytic timer cell

摘要

An elapsed time indicator includes an electrolytic timing cell in series connection with a resistor, which series circuit may be connected to a D.C. voltage. The cell is comprised of an aluminum can containing a liquid electrolyte with an aluminum anode immersed therein. During operation an aluminum oxide film is grown on the surfaces of the anode, the film thickness and resistance increasing with time. The voltage dropped across the cell of any instant is employed as an indication of the accumulated elapsed time during which the D.C. voltage has been connected to the circuit.