Selenium Rectifier / Metal Rectifier queries

Copper oxide was used for quite a while.

Copper oxide was used for quite a while.

Yes. I was going to say exactly the same thing. I think that the original "metal" rectifier, was a copper oxide device, rather than selenium. It's been a long time ago now, but I seem to remember back in my yoof when I was an apprentice, that we talked of metal rectifiers and selenium rectifiers as different entities.

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I'm trying to find if any sort of (presumably) non-thermionic rectifier could fit in a space 95x70x12 mm in the 1940s.

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On Fri, 9 Jan 2009 15:58:28 -0000, "N_Cook" put finger to keyboard and composed:

Search for US patents containing the terms "metal rectifier" and which are assigned to Westinghouse:

For example, US patent 2,802,158 (Aug 6, 1957) refers to "metal rectifier elements which may be selenium rectifiers":

This suggests that selenium rectifiers were just one type of metal rectifier.

Other patents refer more generally to "metal-oxide rectifiers":

- Franc Zabkar

The "whistle" rectifier in Lionel train transformers of the 1950s were copper oxide.

Are you trying to figure out what was in there originally or just want something to fit? I suspect the former since a silicon rectifier, probably with series dropping resistor would work to replace a metal-oxide rectifier. It seems to me that selenium stack rectifiers were not used before about 1945. Copper oxide rectifers were used in "battery eliminators" and were the standard rectifiers in AC meters. I don't think either is made any more but either can be replaced with silicon rectifiers.

I don't think either is made any more but either can

I believe Selenium is still used in the power industry.

Paul P.

I am trying to recusitate a tiny wartime 'scope that someone in the late

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Copper oxide was used for years in movie theaters as rectifiers for the exciter lamp power supplies in the soundheads.

The second to last page of the 1933 Westinghouse book refers to 2 units pictured being used in ""talkie" installations" , but nowhere in the book is there reference to either CuO or Se, just metal rectifiers.

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On Fri, 9 Jan 2009 15:58:28 -0000, "N_Cook" put finger to keyboard and composed:

FWIW, here are some patents of around that time:

SOLID RECTIFYING ELEMENT US Pat. 2030443 - Filed Jul 19, 1934 In order to assure a perfect operation of a selenium rectifier ...

RAILWAY TKACK CIRCUIT APPARATUS US Pat. 2015577 - Filed Nov 9, 1934 - The Union Switch a Signal Company As is well known, the copper oxide rectifier (as 05 well as certain other rectifiers of this type, such as the selenium rectifier) ...

ELECTRICAL DEVICE US Pat. 2124306 - Filed Jul 17, 1935 - International Standard Electric Corporation A method of manufacturing a selenium rectifier having upper and lower metallic members which comprises applying selenium to the- lower member, ...

METHOD OF PRODUCING SELENIUM US Pat. 2121603 - Filed Apr 14, 1937 - The above described treatment of selenium rectifier plates with reducing materials may be applied if necessary to plates of the type in which the selenium ...

Here is a 1931 Siemens patent:

APPARATUS FOB CONTROLLING ELEC US Pat. 1929216 - Filed Apr 1, 1931 - Siemens a Habke ... there occurs a change in the resistance of the individual valves, which may be dry rectifier valves, such as copper oxide or selenium valves, ...

- Franc Zabkar

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What sort of UK names of components catalogues that included non-valve parts of the 1940s , was Radio Spares going then ? Perhaps I should try and find a 1940s Westinghouse cat.

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according to ebay

When did "war dept" cease ? At least another patent number to research

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Hi Copper Oxide have the advantage for things like meters and battery charges because they have a low forward voltage drop. The primary problem is that it has a very low reverse voltage. Even in charger applications, it took a stack of many junctions to hold off the reverse voltage of a 12volt charger. Dwight

Selenium rectifiers date from the mid to late 20's I believe.

Kevin