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IN 5408 Diodes [message #30609] Sat, 19 February 2005 14:39 Go to next message
Manualblock is currently offline  Manualblock
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Illuminati (13th Degree)
3A 1K PIV. O'kay?

Re: IN 5408 Diodes [message #30610 is a reply to message #30609] Sat, 19 February 2005 14:53 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
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Illuminati (2nd Degree)
For the filament supply?

if so, yes they are fine. Not an absolute 'best', but rugged enough and quite functional.
regards,
Douglas

Re: IN 5408 Diodes [message #30612 is a reply to message #30610] Sat, 19 February 2005 17:07 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
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The best; is that higher amp rating?

Re: IN 5408 Diodes [message #30614 is a reply to message #30612] Sat, 19 February 2005 17:19 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
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I would put best in comparable amperage but of the Schottky type. Less recovery noise. That being said, I have used the 1N5408 with no discernable difference in the sonics.

I used SB5100 which are 100 PIV/5A types I got from Mouser. I soldrered too close for too much time and overheated one. It failed short and when run w/o a fuse in-circuit, toasted my RS filament TX. New RS transformer and from my box a set of the 1N5408's. I found no difference.

It's no big deal I think, but knowing I have Schottky diodes makes me feel better.
regards,
Douglas

Re: IN 5408 Diodes [message #30617 is a reply to message #30614] Sun, 20 February 2005 06:53 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
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Illuminati (13th Degree)
Thanks T; I just happen to have 4 of them from another amp that I took out and replaced with Schottkeys. I wonder; what exactly happens when they are wired in series and tied together?

diodes [message #30620 is a reply to message #30617] Sun, 20 February 2005 07:04 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
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Registered: May 2009
Illuminati (2nd Degree)
could you describe the circuit in a bit more detail?

If you mean combine silicon P-N junction diodes with Schottkey barrier type, I am not sure. Certainly increased fwd voltage drop. I have a feeling that the lower PIV would have to be observed.

I spoke with a product engineer from Cree about the SiC Schottkey types they had just introduced. He said that they could be paralleded for increased current but increasing the voltage by putting them in series wouldn't work like silicon P-N types do.
regards,
Douglas


Re: diodes [message #30623 is a reply to message #30620] Sun, 20 February 2005 08:52 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
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Registered: May 2009
Illuminati (13th Degree)
No they were just two Diodes connected in series; soldered one end to one end. I clipped them off the circuit that way. There is two on one channel in series and two on the other. I guess it was originally a diode bridge.

Re: diodes [message #30625 is a reply to message #30623] Sun, 20 February 2005 09:19 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
I think the original app. required a PIV greater than 1kV. Silicon P-N junction diodes add their PIV when rigged in series.

Picture this: increase inverse voltage across your 5408's in series. It builds until it reaches brekdown voltage on one. Current would flow and destroy one, but the second, running at less than breakdown PIV does not allow it to pass. One diode runs at breakdown PIV and the extra is taken across the next one.

Since Schottkey types were nor recommended for this service, I think they must short out in over-voltage failure, and fail in a domino falling scenario.
regards,
Douglas

Re: diodes [message #30627 is a reply to message #30625] Sun, 20 February 2005 09:41 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Ahhh. Now I get it. Sometimes it takes the three pound hammer but eventually I get it.

Bricks for me... [message #30629 is a reply to message #30627] Sun, 20 February 2005 11:46 Go to previous message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
to heck with the hammer...sometimes you can't find one. Bricks and/or rocks are far easier to hand.
regards,
Douglas



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