Editing Rectifier (section)

===={{anchor|Tungar}} Argon gas electron tube ====
[[File:Tungar bulbs.jpg|thumb|upright=0.7|Tungar bulbs from 1917, 2 ampere ''(left)'' and 6 ampere]]

The [[General Electric]] Tungar rectifier was a [[Mercury (element)|mercury vapor]] (ex.:5B24) or [[argon]] (ex.:328) [[gas-filled tube|gas-filled electron tube]] device with a tungsten filament cathode and a carbon button anode. It operated similarly to the thermionic vacuum tube diode, but the gas in the tube ionized during forward conduction, giving it a much lower forward voltage drop so it could rectify lower voltages. It was used for battery chargers and similar applications from the 1920s until lower-cost [[metal rectifier]]s, and later semiconductor diodes, supplanted it. These were made up to a few hundred volts and a few amperes rating, and in some sizes strongly resembled an [[incandescent lamp]] with an additional electrode.

The 0Z4 was a gas-filled rectifier tube commonly used in [[vacuum tube]] car radios in the 1940s and 1950s. It was a conventional full-wave rectifier tube with two anodes and one cathode, but was unique in that it had no filament (thus the "0" in its type number). The electrodes were shaped such that the reverse breakdown voltage was much higher than the forward breakdown voltage. Once the breakdown voltage was exceeded, the 0Z4 switched to a low-resistance state with a forward voltage drop of about 24 V.
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