Date: Sat, 13 May 2017 16:32:23 -0700
From: Paul Baldock <paul@paulbaldock.com>
To: "amps" <amps@contesting.com>
Subject: Re: [Amps] Why a voltage doubler ?
Doesn't a full wave bridge give you better regulation as all
capacitors are charged on both halves of the AC waveform, where as
with a voltage doubler the capacitors are only charged on half the
waveform (half on the positive and half on the negative)?
- Paul
## correct. FWB charges the caps 120 times per sec. FWD is only
60 times per sec. On the doubler, the caps have to hold their charge twice
as long, so they have to be double the value. As carl sez, not big issue these
days
since bigger caps are physical small things.
## Having said that, the 4 x L4Bs I have, are 2650 vdc on RX, 2600, when
drawing
idle current, then down to 2500 vdc, with a 800 ma dead cxr. Thats only a 100
vdc drop between
idle..and full bore load. It appears that the Z of the xfmr is more of the
deciding factor re.... regulation.
## The drake + heath sb-220 xfmr are only 9-11 ohm secondary.
## It comes out a wash with the xfmr. The doubler only requires half the sec
vac, so its
windings can then be bigger gauge..to fit the core. The primaries stay the
same in both cases.
The bigger gauge wire on the doubler xfmr will then handle the higher peak
currents of the
bigger filter caps.
## V drop from the street, or from main panel to HV supply will have more of
an effect on regulation,
depending on load. Bigger caps can help with that too. I used duncans Psud
power supply software,
on gm3seks site...and played with more C. Put enough in there, and even with
a dead cxr, the regulation
was identical between the doubler and the FWB. But with just ssb + cw,
its dynamic regulation you are
concerned with..vs static regulation. Psud only simulates static
regulation.
Jim VE7RF
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