Talk:Metal rectifier

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Specs and v/i graphs would be nice. Metal recs do behave differently to silicon. Tabby (talk) 04:14, 5 March 2008 (UTC)[reply]

And also on details of the working is necessary. —Preceding unsigned comment added by 117.211.86.74 (talk) 11:15, 19 April 2011 (UTC)[reply]

Distinction from Schottky diodes

I'm told that these are distinct from Schottky diodes but it's not apparent why that might be...

It would be good to have a remark on the physical mechanism at play. --Nanite (talk) 18:22, 9 June 2013 (UTC)[reply]

It's not that they're particularly different from Schottky diodes, it's that the common-or-garden silicon diode isn't a Schottky diode. Your addition "A semiconductor rectifier using a modern semiconductor (e.g., silicon instead of selenium) is called a Schottky diode." is incorrect. It remains incorrect, even though metal rectifiers can be said to be Schottky diodes (although I've never heard them called such) and the modern replacement for a large metal rectifier is often a Schottky diode.

Modern Schottky diodes have a lower forward voltage drop than a conventional silicon diode, which gives two advantages:

There is less voltage drop in the system. This matters in low voltage systems; most commonly in 12V vehicles or trailers with twin battery systems, although PV battery charger systems are probably running that a close second these days.
Less voltage across the diode means, for a given current, less heat generated in the diode, less heatsinking required and better reliability.

In comparison, mere facts such as "less wasted power" are pretty secondary.

To repair an old domestic car battery charger (a common place for metal rectifiers), a dead metal rectifier can be replaced by a couple of silicon diodes the size of a pencil stub and costing coppers. To replace a charger charging milk floats, a Schottky diode might well be used instead.

On the whole, I see no value (and a large risk of confusion) in introducing Schottky diodes so early on in this article. Andy Dingley (talk) 18:52, 9 June 2013 (UTC)[reply]

Aha, oops, I definitely misworded that. By the way, looking around I found an interesting video about selenium rectifiers[1]. It looks like they do behave a lot like Schottky diodes in forward bias but they leak quite a bit on reverse... probably due to their polycrystalline nature or dirty construction that gives an inhomogeneous Schottky barrier. Interestingly, they show hysteresis on reverse bias, though I wonder if it is a high frequency transient effect since the curve tracer is tracing so fast. --Nanite (talk) 21:24, 9 June 2013 (UTC)[reply]

Beware when replacing a metal rectifier with silicon, the forward resistance is often needed and bad things can happen without it. Tabby (talk) 11:53, 29 August 2013 (UTC)[reply]

Can anyone write more about the construction properties and time of use of the copper oxide rectifier?

The selenium rectifier is covered by a separate article but there is precious little about the copper oxide rectifier. (I think it's the copper(I)oxide that was used).150.227.15.253 (talk) 11:48, 18 March 2020 (UTC)[reply]

Copper-oxide rectifier

At some point down the road, we might want to consider overhaul/split/merge "Metal rectifier" and "Selenium rectifier" articles. Maybe split this article into a new "Copper-oxide rectifier" article, or maybe merge this article with "Selenium rectifier" article? • Sbmeirow • Talk • 04:15, 17 December 2020 (UTC)[reply]

metal?

Since both selenium and copper oxide are semiconductors, why is the article called metal rectifiers? Gah4 (talk) 20:38, 25 October 2021 (UTC)[reply]

I think because these devices are created out of a sandwich of metal layers and semiconductor layers. For selenium rectifiers, the base metal layer plate is typically aluminum (aka metal). See drawings in books at Selenium_rectifier#Further_reading. • Sbmeirow • Talk • 21:39, 25 October 2021 (UTC)[reply]