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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 17, 2021 12:52 am 
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Stock them and some day in the future you'll make a small fortune of them :D ... or not ! :(

Well, ok then!! I'll pack them all up and send them to you instead of Rich ;-)

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 17, 2021 1:58 am 
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Barry H Bennett wrote:
Quote:
Stock them and some day in the future you'll make a small fortune of them :D ... or not ! :(

Well, ok then!! I'll pack them all up and send them to you instead of Rich ;-)


That's very kind of you...

Now I need some time to install the hype in the audiophile community... I'll take care of the guitar amp freaks later.
The rectifiers will be sold by pairs housed in a very elegant walnut box (with lock, keys and extra gloves) at the paltry introductory price of $ 700,00 ($ 950,00 with cryogenic treatment) Pre-orders recommended.

Still need to find some fancy name for the product. Any ideas ?


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 17, 2021 2:02 am 
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The rectifiers will be sold by pairs housed in a very elegant walnut box (with lock, keys and extra gloves) at the paltry introductory price of $ 700,00 ($ 950,00 with cryogenic treatment) Pre-orders recommended.

a few suggestions:

*First of all, it is going to be very important that they be sold in MATCHED pairs. That way the user can maintain sonic purity by assuring equal excursions to the positive and negative. I'm positive of this.

*The other major suggestion is that the elegant walnut box be insulated, and the rectifiers shipped packed in dry ice. Don't want to take any chances

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 17, 2021 2:42 am 
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But seriously (not really) what about fuzz boxes? They need diodes to clip the signal, would selenium rectifiers give some unique sound?

I don't recall seeing selenium rectifiers for anything but rectifying AC in power supplies.


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 17, 2021 1:32 pm 
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mblack wrote:
But seriously (not really) what about fuzz boxes? They need diodes to clip the signal, would selenium rectifiers give some unique sound?

I don't recall seeing selenium rectifiers for anything but rectifying AC in power supplies.



Knee (conduction) voltage of most H.V selenium rectifiers stacks is too high for solid state circuits and their function transfer not sharp enough for hard audio clipping or distorsion generating devices (Fuzz-boxes).
Maybe it can be done but you should use low voltage/current selenium (dual) rectifiers like those used in old television AFPC circuits, which is an exemple of an application different from standard AC power supply rectifier where selenium rectifiers were usually found. Small selenium diodes were also used as AC meter rectifiers in old VOM's.
Of course some experimentation would be needed and we can expect that the distorsion harmonic spectrum will be different from (Si or Ge) clipping diodes. But most (if not all) fuzz box schematics I've seen so far used under biased transistors as a distorsion source and not clipping diodes...

A "Selenium Fuzz-Box" would be a good marketing ploy...


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 17, 2021 6:49 pm 
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A "Selenium Fuzz-Box" would be a good marketing ploy...

and ..... you could include a few selenium pills for that chemically enhanced experience ....

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Fri 18, 2021 1:07 am 
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I recently sold about a dozen 50 yr-old Germanium transistor "pulls." Still favored in fuzz boxes.

If you do try to sell those seleniums, ask a fairly high price. That always enhances the mystique.

Rich


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Sat 19, 2021 4:06 pm 
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Hi Barry,

What is the largest selenium rectifier you have ?

Dennis


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Sat 19, 2021 5:58 pm 
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Dennis Banker wrote:
Hi Barry, What is the largest selenium rectifier you have ? Dennis

.....dimensions? weight? current capability? number of sections? cubic volume of otherwise valuable storage space?

In a word, I don't know the answer to any of those but I know someone who can find out lol. Let me know which of the above you're interested in and I'll take a look eventually

b

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Sat 19, 2021 10:04 pm 
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When Westinghouse was still making selenium, I think our max plate size was about 9 inches on a side.

Rich


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Sun 20, 2021 12:23 am 
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I don't recall seeing anything nearly that large. Probably 3" perhaps ?

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Sun 20, 2021 1:34 pm 
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Hi Berry,

I was thinking of physical size. Maybe 3-4 inch square and 4-6 inches long. I saw one about this big sometime ago. I need ones like this for a prop.

Dennis


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Sun 20, 2021 7:10 pm 
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Quote:
I don't recall seeing anything nearly that large. Probably 3" perhaps ?


If your experience is with radios and hifi, you probably never saw a REAL selenium rectifier. These were used in welders and electroplating power supplies until about 1975.

https://www.cehco.com/products-line/selenium-rectifier/selenium-rectifier-repair-pn-5303c/

Image

These are 6 x 10"

I once helped convert a 1000 A DC supply used for electro-etching. It was 3 cabinets, each the size of a 25 cu. ft. refrigerator full of selenium plates (in parallel) forced-air cooled by large fans. We replaced all of it with one 3-phase silicon bridge the size of a Zenith T-O radio!

http://www.dalitech.com/Resources/Water ... 0CKE36.pdf

Image

The factory was a lot cooler after the conversion. More energy was wasted in the selenium stacks than actually got into the load, which usually needed less than 10 V. !

Rich


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Sun 20, 2021 7:25 pm 
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If it's for a prop, then make one. It doesn't have to work. Big squares of cardboard or even metal, with something connecting them, and don't forget to paint it.


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Tue 22, 2021 1:16 pm 
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That is my fall back position. I am starting to make a large mock up.

Thanks,
Dennis


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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 24, 2021 2:19 am 
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Maybe there's a market for them drilled out and stuffed with a silicon diode? :D

You'd want your diode hole to one side of the mounting bolt. You'd be drilling cadmium,, good excuse to buy a respirator. You'd need an insulated sleeve in there. Then you need a convincing sales pitch. :D

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jun Thu 24, 2021 1:04 pm 
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westcoastjohn wrote:
Maybe there's a market for them drilled out and stuffed with a silicon diode? :D You'd want your diode hole to one side of the mounting bolt. You'd be drilling cadmium,, good excuse to buy a respirator. You'd need an insulated sleeve in there. Then you need a convincing sales pitch. :D

:::::packing them all up to ship to westcoastjohn ;-)

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jul Mon 12, 2021 3:38 pm 
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Ok, a bit of an update: There are no LARGE ones... the biggest is approximately 2" square with about 6 plates, although there are a few with a lot more plates.

One specific number was requested, and I'll take a look for that one today or tomorrow.

So I take it no one wants the rest? ;-) :lol:

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 Post subject: Re: NOS Selenium Rectifiers
PostPosted: Jul Mon 12, 2021 4:36 pm 
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Au Contraire, PM coming.

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