Selenium rectifier

[1] They were used in power supplies for electronic equipment and in high-current battery-charger applications until they were superseded by silicon diode rectifiers in the late 1960s.

Compared with the earlier copper-oxide rectifier, the selenium cell could withstand higher voltage, but at a lower current capacity per unit area.

[4] Selenium rectifiers are made from stacks of aluminum or steel plates coated with about 1 μm of bismuth or nickel.

Cadmium selenide forms by reaction of the selenium with the tin-cadmium alloy and the CdSe-Se heterojunction is the active rectifying junction.

Stacks of thousands of miniature selenium disks have been used as high-voltage rectifiers in television sets and photocopy machines.

It is commonly used in electroplating rectifier under 200,000 A and electrostatic precipitators operating between 30 and 100 kV[5] Radio and television receivers used them from about 1947 to 1975 to provide up to a few hundred volts of plate voltage.

During catastrophic failure they produce significant quantities of malodorous and highly toxic hydrogen selenide[8][9][10] that let the repair technician know what the problem was.

[11] In 1961 IBM started developing a low-speed computer logic family[12] that used selenium diodes with similar characteristics to silicon but cost less than one cent.

A design was achieved for a DDTL circuit with two levels of diode logic feeding one alloy transistor and no series input resistor or speed-up capacitor.