[AMPS] Voltage Doublers

[Steve Thompson]

-----Original Message-----
From: Ian White, G3SEK <G3SEK@ifwtech.com>
To: amps@contesting.com <amps@contesting.com>
Date: 16 May 2001 13:04
Subject: Re: [AMPS] Voltage Doublers


>
>Glenn McNeil wrote:
>>
>>A few questions about voltage doublers. I'm building a single tube 4CX250R
for
>>70cm using a voltage doubler
>>supply. This is my first attempt at FWD supplies.
>>
>>I have a transformer with about 750vac secondary, 12ohms dc resistance.
I'm
>>planning on using IN5408 diodes and
>>a string of electro's.
>>
>In one word, DON'T. The secondary resistance of the transformer -
>combined with the effects of primary resistance and diode on-resistance,
>which you also need to factor in - will ruin the voltage regulation.
Are you being a bit harsh on the transformer here, Ian? 12 ohms strikes me
as quite low.

Assuming a total source resistance of 50 ohms, simulation with 2 x 100uF
caps shows 1.2A rms in the transformer, 800mA rms in the caps and 66V ripple
at 300mA dc. Doesn't seem too unreasonable to me but I'd agree with you that
it's well worth breadboarding it before committing to metalwork.

Steve


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