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 redrabbit 12th November 2006 02:43 AM

diode rectifier ratings

a PSU for class A/B 80w amp....full wave rectifier question:

If the design calls for a 35a bridge, but I want to use 4 diode rectifiers instead, what amperage should each diode be?
Is it:
four 8amp diodes = 32amps?
......or should each diode be 35a.....naw, they'ld be huge :irked:

??

=RR=

 SY 12th November 2006 03:41 AM

35A per. Sorry.;)

 sivan_and 12th November 2006 03:47 AM

15 amp each diode...whats the VCC ? supply voltage

 redrabbit 12th November 2006 04:18 AM

Quote:
 Originally posted by sivan_and 15 amp each diode...whats the VCC ? supply voltage
it's for a Cap Filter supply, dual polarity, transformer is 28-0-28v, @2.7amps.
115v primary.
Toriodal.

=RR=

 sivan_and 12th November 2006 07:41 AM

28-0-28v, @2.7amps....its too small VA for 80watts class AB

 AndrewT 12th November 2006 07:28 PM

Hi,
this is going to sound completely opposite to my usual play safe philosophy but let's just describe what is in my Sugden P128s (about 180W into 8r).

Each 52Vac winding passes through a diode bridge formed from four 1n5404s, feeding 20mF charged to 72Vdc. Iq=300mA.

They have never gone pop and there is no soft start.
So the dual polarity supply +-72Vdc is fed from 8 diodes as two bridges in series, the centre point being PSU 0volts. Yes, 3A diodes seem to be very reliable.

 redrabbit 12th November 2006 09:13 PM

Quote:
 Originally posted by sivan_and 28-0-28v, @2.7amps....its too small VA for 80watts class AB
You are correct, I was exagerating the specs a bit.

AndrewT....you rebel, life on the edge is sweet !

I'll most likely use the overkill 35a bridge, but was hoping to use four 6 amp diodes I have........they fit better in the enclosure.
Oh well.

=RR=

 redrabbit 13th November 2006 02:33 AM

It still has me thinking.....
What is in a 35a encapsulated bridge rectifier ? :scratch:

Are there really four 35a diodes in there? :magnify:
......or are the diodes lower value, and the encapsulation/termination-package qualifies it to become rated at a higher amperage, compared to individual (discreet) diodes ?

:snail: :whip:

=RR=

 peranders 13th November 2006 06:33 AM

A 35 A rectifier bridge consists of four 35 A diodes.

Most bridges are made for 50/60 Hz applications if you mean by that "lower value".

You can also build a rectifier bridge with discrete diodes, then you can choose the diodes with taste which means faster diodes.
Example here:
http://home5.swipnet.se/~w-50674/hif...0_overview.jpg
http://home5.swipnet.se/~w-50674/hif...r0_topview.jpg

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