With such a close match why bother?
I would be more concerned about using those diodes at all since you will be
running them with only a small margin. Do you know their full specs?
A typical commercial amp power supply of that capacity will use a 1N5408
diode for a wide safety margin from surges and line voltage spikes. It is
rated at 1KV @ 3A but more important is the 200A peak surge current. Small
quantity price is around $.15 each.
Carl
KM1H
----- Original Message -----
From: "Angel Vilaseca" <avilaseca@bluewin.ch>
To: <amps@contesting.com>
Sent: Friday, November 16, 2007 7:40 AM
Subject: [Amps] Using HV rectifiers from microwave ovens
> Hi,
>
> For my 3000 V , 500 mA power supply, I will use some microwave oven
> rectifiers, which are rated 7 Kv, 500 mA. To increase the current safety
> margin I will wire two rectifiers in parallel in each side the rectifier
> bridge.
>
> The rectifiers are unused, all from the same batch. I measured the
> forward voltage drop in each of them. It is 3.4 Volts plus or minus 0.02
> V.
>
> To equalize current in each of the two rectifiers of a pair, I will
> connect a resistor in series with each rectifier.
>
> My question is: which value would be right for the resistors?
>
> I was thinking of using about 1 ohm. This would produce a voltage drop
> of about 0.5 volts at 500 mA. Ten times more than the mismatch between
> two individual rectifiers. Does this seem right?
>
> Has anyone tried this?
>
> Angel Vilaseca HB9SLV
>
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>
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