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Sci.Electronics.Basics -> Need Voltage Doubler Circuit
There are 27 messages in this thread.
You are currently looking at messages 20 to 27.
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Author: Phil AllisonDate: 07:59 25-04-08
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"Mike Silva
> "Phil Allison"
>
> ** The standard voltage doubler has exactly the *same* ( load ) percentage
> regulation as the same transformer would provide with a bridge rectifier
> and
> capacitor filter.
>
> http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/voldoub.html
Are we sure about that?
** Yes - so fuck off.
Only one-half of the capacitor stack is
charged each half cycle, but both capacitors are discharging each half
cycle.
** So what - shithead ???
Ripple voltage depends on cap value, so can be made as small as you like.
Which brings up a circuit I ran across years ago and was able to find
again yesterday. This one claims to charge both capacitors each half
cycle, making it a true full-wave circuit. I haven't tried it or
analysed it - I just put it out for consideration.
http://www.kwarc.org/bulletin/99-04/tech_corner.htm
** The claims made are complete BOLLOCKS.
A "standard voltage doubler" generates 120 Hz ( or 100Hz ) ripple and
utilises the transformer just as fully as a bridge rectifier.
The page was written by a ham -
so you KNOW it is TOTAL SHIT !!!
....... Phil
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Author: Mike SilvaDate: 08:11 25-04-08
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On Apr 25, 7:59=A0am, "Phil Allison" <philalli...@tpg.com.au> wrote:
I knew you'd have one of your outbursts on this, but I thought the
question interesting enough to endure it. I hope others will weigh
in.
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Author: Phil AllisonDate: 08:57 25-04-08
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"Mike Silva the fucking Cunt Head "
** Why don't you go eat a box of rat poison ???
Do the planet a favour by bleeding to death.
... Phil
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Author: Dave.HDate: 10:55 25-04-08
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On Apr 25, 2:04 am, John Popelish <jpopel...@rica.net> wrote:
> Dave.H wrote:
> > On Apr 25, 1:38 am, "Dave.H" <the19...@googlemail.com> wrote:
> (snip)
> >> I might go with that bridge rectifier option. Sounds simpler, and I
> >> believe I have a 2,200 MFD, 50 volt cap lying around.
>
> > I found a 30 volt, 500 mA transformer I'll use with the bridge
> > rectifier, Smaller and cheaper than the one amp unit. I think the
> > current draw of the radio is only about 8-10 mA. Transformer is M2860
> > @www.dse.com.au.
>
> Sounds like a plan. The light load voltage may be something
> like 33 volts, so the peak would be 33*sqrt(2)=47, but the
> bridge will waste about 2 volts. so that might do very
> nicely. At that low current, the 2,200 uF capacitor will
> produce a low ripple output. If the voltage comes out a
> little high, add a resistor in series with the either the 30
> volt secondary, or in series with the primary.
>
> --
> Regards,
>
> John Popelish
Should I regulate the output? How about a voltage regulator IC like
the LM317?
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Author: Rich GriseDate: 13:58 25-04-08
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On Fri, 25 Apr 2008 04:45:37 -0700, Mike Silva wrote:
> On Apr 24, 10:01 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
>> ** The standard voltage doubler has exactly the *same* ( load ) percentage
>> regulation as the same transformer would provide with a bridge rectifier and
>> capacitor filter.
>>
>> http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/voldoub.html
>
> Are we sure about that? Only one-half of the capacitor stack is
> charged each half cycle, but both capacitors are discharging each half
> cycle.
>
> Which brings up a circuit I ran across years ago and was able to find
> again yesterday. This one claims to charge both capacitors each half
> cycle, making it a true full-wave circuit. I haven't tried it or
> analysed it - I just put it out for consideration.
> http://www.kwarc.org/bulletin/99-04/tech_corner.htm
>
I don't know why anyone could need anything that's not here:
http://www.tpub.com/neets/book7/27m.htm
Cheers!
Rich
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Author: Paul E. SchoenDate: 15:49 25-04-08
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"Mike Silva" <snarflemike@yahoo.com> wrote in message
news:81006d7a-65d7-411a-946b-e8184dfde0ee@p25g2000hsf.googlegroups.com...
On Apr 24, 10:01 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
> ** The standard voltage doubler has exactly the *same* ( load )
> percentage
> regulation as the same transformer would provide with a bridge rectifier
> and
> capacitor filter.
>
> http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/voldoub.html
Are we sure about that? Only one-half of the capacitor stack is
charged each half cycle, but both capacitors are discharging each half
cycle.
Which brings up a circuit I ran across years ago and was able to find
again yesterday. This one claims to charge both capacitors each half
cycle, making it a true full-wave circuit. I haven't tried it or
analysed it - I just put it out for consideration.
http://www.kwarc.org/bulletin/99-04/tech_corner.htm
==============================================================================
Two of those diodes are superfluous, and otherwise it is a standard dual
output voltage doubler, similar to what I posted with an LTspice ASCII
schematic. If your load is fairly constant and no more than a couple of
watts, the string of zeners (or a single 48V zener) in that circuit will
give you decent line and load regulation. It also has the advantage of
current limiting, so a short circuit on the output can be tolerated. It's
dirt simple, cheap, and meets your requirements. You don't need a fancy
voltage regulator, and you would need an LM317H to get a 48 VDC output, and
you might also exceed its 60 VDC input maximum.
Paul
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Author: John PopelishDate: 18:05 25-04-08
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Dave.H wrote:
> Should I regulate the output? How about a voltage regulator IC like
> the LM317?
I suspect you might be able to get by with sufficient
filtering, but if you want to try regulation, you need a
unit that is rated for the full supply across the regulator,
like the TL783 (less than $2 from Digikey).
http://focus.ti.com/lit/ds/symlink/tl783.pdf
Keep in mind that you have to start with a supply that stays
at least 2 volts above the regulated output, even at the
bottom of the ripple and at low line voltage, so you will
need a significant extra voltage at the input supply.
--
Regards,
John Popelish
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