small ignitron mercury rectifier
Date: 1947-1960
Inventory Number: 2003-1-0126
Classification: Rectifier
Subject:
Maker: National Electronics (founded 1947)
Cultural Region:
Place of Origin:
Dimensions:
26 x 18 x 14 cm (10 1/4 x 7 1/16 x 5 1/2 in.)
Description:
A cylindrical glass tube with a pool of mercury at the bottom mounted vertically on a wooden stand with a semicircular base.
The tube consists of a mercury pool at the bottom that acts as a cathode, a large graphite cylinder hanging from the ceiling that acts as an anode, and a small ignitor which is a small electrode on the bottom with a tip submerged in the mercury.
The bottom of the tube tapers off to a narrow tube with a valve.
The tube consists of a mercury pool at the bottom that acts as a cathode, a large graphite cylinder hanging from the ceiling that acts as an anode, and a small ignitor which is a small electrode on the bottom with a tip submerged in the mercury.
The bottom of the tube tapers off to a narrow tube with a valve.
Signedstamped in red on glass: NATIONAL IGNITRON / NL-1001 / NATIONAL ELECTRONICS / GENEVA, ILLINOIS U.S.A.
Inscribedhandwritten label: IGNITION EDUCATIONAL TOOL
FunctionIgnitrons were a kind of mercury vapor rectifier developed by Westinghouse. As other rectifiers, they were used to transform AC current to DC. Most were very large, in the order of one foot, and designed to convert thousands of volts. This particular model here is very small. These also existed so it is not necessarily a demonstration model, although it may have been used as one.
Some of the smaller ignitrons were used in welders.
In ignitrons, when a large voltage is present between the cathode and the anode, an electric arc forms between them allowing current to pass. The current has to originate with the mercury pool functioning as the cathode. When the voltage is inverted, no arc forms because the graphite anode does not give of electrons easily. An important feature of ignitrons is the small igniter on the mercury pool. This igniter is the first place where the arc originates before extending all the way to the anode.
Some of the smaller ignitrons were used in welders.
In ignitrons, when a large voltage is present between the cathode and the anode, an electric arc forms between them allowing current to pass. The current has to originate with the mercury pool functioning as the cathode. When the voltage is inverted, no arc forms because the graphite anode does not give of electrons easily. An important feature of ignitrons is the small igniter on the mercury pool. This igniter is the first place where the arc originates before extending all the way to the anode.
Curatorial RemarksWARNING: MERCURY PRESENT.