Preferred rectifier diodes for 12.6V 2A full-wave rectifier?

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Deke609

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on: October 13, 2019, 07:28:37 AM
Is there a preferred type/model for reliability and low noise? 

many thanks, Derek


Offline Paul Birkeland

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Reply #1 on: October 13, 2019, 07:32:59 AM
Is this for the fan supply or the 300B?  Bridge, full wave, or doubler?  Have you modeled the power supply to look at the rectifier current?

Paul "PB" Birkeland

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Deke609

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Reply #2 on: October 13, 2019, 07:37:19 AM
For the 300Bs. Full wave. I've modeled it in PSUD but didn't look at the current at the diodes. Will do so now.


Deke609

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Reply #3 on: October 13, 2019, 07:39:56 AM
Whoah! Wasn't expecting that - PSUD shows momentary spikes of 4.5A at the diodes.


Offline Paul Birkeland

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Reply #4 on: October 13, 2019, 07:50:37 AM
Yeah, the design of the power supply will determine what you need for a diode.  I tend to go for whatever Schottky will tolerate the PIV and drop the least forward voltage.

Paul "PB" Birkeland

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Deke609

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Reply #5 on: October 13, 2019, 08:03:17 AM
Many thanks PB. I had a PIV problem in PSUD when I tried the 1N5822 (40V), but that went away when I chose the 1N5801 (100V and 99A).

What current rating should I go for to deal with the 4.5A spikes? Before seeing the spikes I was looking at some Si Schottkys rated 100V and 5A, but I'm worried now that this might be cutting it close. 

Also concerned about reverse noise spikes from the Si diodes - even though I'll be snubbing the filament transformers. But can't seem to find non-Si types when I search in Mouser.

[Edit: I should add that I still have a bunch of new IXYS TO-220 diodes from when I was trying to tweak the stock Beepre filament supply - but they're rated 10A 45V, and PSUD shows my circuit hits the diodes with nearly 41V - so I figured these would not be robust enough.  maybe I need to explore using a 6.3 CT transformer with a doubler].

cheers and thanks, Derek
« Last Edit: October 13, 2019, 08:10:03 AM by Deke609 »


Offline Paul Birkeland

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Reply #6 on: October 13, 2019, 08:12:01 AM
You don't need 100V diodes for this, and the diodes that you're most likely to use won't be in the PSUD database.

Spikes are an indication of peak current, I'd pay more attention to RMS current in PSUD.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Deke609

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Reply #7 on: October 13, 2019, 08:30:23 AM
Many thanks again PB. I see now that the diode specs for the IXYS are quoted for average forward current, and V rms (actually, "RSM"), not peak. So I should be good. I'll breadboard the filament supply and see if it works ok.

cheers, Derek


Offline grufti

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Reply #8 on: October 13, 2019, 12:26:57 PM


Deke609

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Reply #9 on: October 13, 2019, 04:57:22 PM
Many thanks for this. They look interesting. And would work well with the diy protoboard setup I have planned for the fil transformer, rectifier and CLC filter that will feed the LM1085 board.

cheers, Derek


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