Best Rectifier Diode to use?

Discussion in 'Shock Brother's DIY Amps' started by TobyZ28, Jan 24, 2020.

  1. TobyZ28

    TobyZ28 Tele-Meister

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    Simple question with probably a complex answer.. I'm doing the "Rectifier Backup Diodes" mod in my build. I have two diodes on hand and am wondering if anyone can definitively which one would be best/ideal for a 5E3 build. It looks like both will work, just wondering if there are any advantages or disadvantages of one over the other!

    BYV26E - Datasheet
    1N4007 - Datasheet

    Googling gave me very limited results :(

    Thx!
     
  2. kbold

    kbold Tele-Afflicted Silver Supporter

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    The "rectifier backup diode" mod specifies 1N4007's. I would stick with that.
    An improvement over 1N4007's would be to use UF4007's which have faster switching. These are cheap and an upgrade for any 1N4007 application.
    The BYV26E is a different construction (not a standard silicon diode). It may be OK here, but I don't know. It's forward voltage drop is greater, so I would assume it gets hotter.

    This would be a useful read:
    https://www.allaboutcircuits.com/te...oft-schottky-whats-the-right-rectifier-power/
    https://www.allaboutcircuits.com/te...ndard-schottky-selecting-the-right-rectifier/
     
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  3. FenderLover

    FenderLover Poster Extraordinaire

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    You show the BYV26E, but the BYV26G would be a better choice. The PIV spec is higher, and they all handle 1A.

    I have a problem with the Backup Diode mod. The backup diodes are to back up the tube rectifier if it fails. The meaning of 'backup'. They are in series with the tube diode. If the tube rectifier fails open, the backup diodes will do nothing. If the tube rectifier fails short, the backup diodes are there to save the day by carrying the amplifier's full load. However.... A single diode shown in the Backup Diode mod does not have sufficient PIV rating to handle the full load of the amplifier.

    In the words of Merlin Blencowe:
    "A 1N4007 is rated for 1000V. This corresponds to an AC voltage of 1000V/2.8 = 357Vrms. Knock off 10% to allow for variation in mains voltage, plus another 10% for transformer regulation and we are left with about 290Vrms. In other words, we shouldn't use the 1N4007 with anything more than a 290-0-290V transformer."

    No one would use a single diode to build an amplifier with solid state rectifiers using a transformer with 600VCT or greater. Use two in series, some use three. This is the case with a failed (open) tube rectifier using a single backup diode. Maybe it's better than nothing, on a wing and a prayer. We hope that it will last until you notice the tube rectifier failed and can replace it.
     
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  4. sds1

    sds1 Tele-Afflicted

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  5. TobyZ28

    TobyZ28 Tele-Meister

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    These are the exact two i have actually! Thanks all for the input, sounds like they are both sufficient unless anyone else chimes in- they were shipped with kit by surprise, and i had already bought the 1N4007's.

    FenderLover/Kbolds thanks for the info!
     
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