[Amps] Why a voltage doubler ?

[Jim Thomson]

Date: Sat, 13 May 2017 16:32:23 -0700
From: Paul Baldock <paul at paulbaldock.com>
To: "amps" <amps at 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