I have a standard electrical outlet supplied by a 20 amp breaker, outputting
118 volts. For something being planned, that circuit is needed to output 125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of theory,
so be gentle.

Thanks,
RJ

In article . net,
Backlash wrote:

I have a standard electrical outlet supplied by a 20 amp breaker, outputting
118 volts. For something being planned, that circuit is needed to output 125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of theory,
so be gentle.

Thanks,
RJ


A 20 amp 6.3 volt filment transformer used in series with the line as a
boost trans. should do the trick. The trick will be to find such a
tran. in this day and age. What is so critical that you can't use 118
volts. Signal Tran. Co. has a very good selection of power trans.

Chuck P.

Backlash wrote:

I have a standard electrical outlet supplied by a 20 amp breaker, outputting
118 volts. For something being planned, that circuit is needed to output 125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of theory,
so be gentle.

Thanks,
RJ


You only need a transformer to supply the difference (7 V) at 20 A.
6.3V should be near enough and some old gear had absolutely massive
transformers for the valve heaters. I dismantled some old test
equipment back in the 80's that had an 8A heater winding. Ask Gunner if
he's got any suitable transformers.

When you've got one, connect the secondary in series with the live wire
to the load and the primary accross the suppply. If the output voltage
is reduced from the input, reverse the secondary connections, its phased
wrong. Warning: you will draw approx 5% more current from the supply
than the load takes.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.

I haven't seen anything that can't take a 5 percent drop in voltage.
IIRC, 117 is actually the mathmatical number for what we call 120 volts.

Wht is the application?

On Thu, 10 Feb 2005 22:24:27 GMT, "Backlash"
wrote:

I have a standard electrical outlet supplied by a 20 amp breaker, outputting
118 volts. For something being planned, that circuit is needed to output 125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of theory,
so be gentle.

You need a device called a Variac, which is a variable
autotransformer.
http://www.variac.com/staco_Variable...former_Map.htm
Buying a new one would be pricey, but they've been around for a long
time and can be found at surplus outlets, auctions and even junkyards
that have electical/electronic stuff.

Trying to do it with a parasite transformer is tricky as the line
voltage is rather variable with time of day and local load.

Is the precise 125 volts really necessary? Is regulation critical?

Ian Malcolm wrote:

Backlash wrote:

I have a standard electrical outlet supplied by a 20 amp breaker,
outputting
118 volts. For something being planned, that circuit is needed to
output 125
volts at 20 amps capability. Is there a good method for this, and
what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of
theory,
so be gentle.

Thanks,
RJ


You only need a transformer to supply the difference (7 V) at 20 A.
6.3V should be near enough and some old gear had absolutely massive
transformers for the valve heaters. I dismantled some old test
equipment back in the 80's that had an 8A heater winding. Ask Gunner
if he's got any suitable transformers.

When you've got one, connect the secondary in series with the live
wire to the load and the primary accross the suppply. If the output
voltage is reduced from the input, reverse the secondary connections,
its phased wrong. Warning: you will draw approx 5% more current from
the supply than the load takes.

As a refinement you can use a small Variac (adjustable transformer) to
feed the 120 volt feed to
the 7 volt transformer. Variac's in the 3 Amp size are readily available.

Bill K7NOM

I built a buck transformer system, using a commercial new
autotransformer, to deal with a high voltage situation, 15 amps rating.
Info on my web site below. If you know your voltage in and out and
amps, call the supplier and they will recommend a specific autotransformer.

http://peregrino.home.att.net/camper/transformer.html

There is nothing wrong with using a 5 or 7 volt transformer to buck or
boost, as long as it is rated for the required current.

Check the wiring twice and check the voltage in and out before you try
to use your buck/boost transformer system.

I wonder also what is so critical that it cannot run on 118 volts. Most
equipment will run at +5% - 10% voltage.

Richard


Backlash wrote:

I have a standard electrical outlet supplied by a 20 amp breaker, outputting
118 volts. For something being planned, that circuit is needed to output 125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of theory,
so be gentle.

Thanks,
RJ

Get yourself a Sola 'Constant Voltage Transformer'. I got mine from as local
company 'cleaning out old junk' and it's good for about 30 Amps! Weighs
about 80 friggin' ponds( think sack of cement as big too!).
probably find them on Ebay, local colleges,electrical test shops,etc.
Any other method of stepup transformers,Variac etc will NOT be regulated
which is what I think you want. Anyone that sells Variacs should know/have
the Sola

See
http://www.grainger.com/Grainger/pro...603427&ccitem=

This unit will give you a 12 V boost and will carry the full circuit
capacity. Plus it is an approved device that meets NEC code.

Randy


"Backlash" wrote in message
ink.net...
I have a standard electrical outlet supplied by a 20 amp breaker,
outputting
118 volts. For something being planned, that circuit is needed to output
125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of
theory,
so be gentle.

Thanks,
RJ

Why do you need exactly 125VAC???
Line voltage from the power company is somewhere between 108VAC and 135VAC
and equipment designed to run on the line voltage will run correctly
anywhere in this range. As such, hook up your equipment and enjoy.
If you have a specific requirement for exactly 125VAC I'd love to hear about
it. Please note that a piece of equipment that says it runs on 125VAC is
more likely an old piece of equipment that doesn't have the more mondern
108-135VAC tag on it. Electric power is electric power for all practible
purposes.

--
Why isn't there an Ozone Hole at the NORTH Pole?

For a 20A demand from a 20A breaker, you're most likely gonna have other
problems.
Small variacs or small transformers won't be much good.

Any application that requires 20A should never be connected to a standard
household wall receptacle.
Installation practices often vary from insanely wrong to barely adequate,
and device design specifications are questionable, even when the parts are
new.

In case you don't already know, line voltages fluctuate. All 'ya gotta do is
stick a sensitive chart recorder on your supply, and watch it for a week.

If you absolutely need to have 125VAC minimum, you might consider coming
down from 240V (apparently 236 in your case) instead of going up from 118V.

...the most economical, feasable, and most practical method?

What about safe?
Electrocution might not be so bad, but I suppose death by fire is nasty

WB
..............

"Backlash" wrote in message
ink.net...
I have a standard electrical outlet supplied by a 20 amp breaker,
outputting
118 volts. For something being planned, that circuit is needed to output
125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of
theory,
so be gentle.

Thanks,
RJ






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On Thu, 10 Feb 2005 22:24:27 GMT, "Backlash"
wrote:

I have a standard electrical outlet supplied by a 20 amp breaker, outputting
118 volts. For something being planned, that circuit is needed to output 125
volts at 20 amps capability. Is there a good method for this, and what is
the most economical, feasable, and most practical method? It needs to be
fairly close to the 125 volt figure, as much as practical. Obviously, a
step-up transformer might be the solution, but what about the ability to
find one to output the 125 volts? Is there a practical homebrew buck and
boost method? I've done a decent amount of industrial, automotive, house
wiring and troubleshooting, but I'm a relative newby at this type of theory,
so be gentle.

Thanks,
RJ

For lower current requirements I have made buck-boost transformers
from old filament power transformers. Say you have 112 volts and need
124, you tie one end of the 12 volt vilament winding to the primary,
and if you got the right ends together going frm the other end of the
primary to the free end of the secondary, you will have 124 volts. If
you got the wrong end connected, you will have 100.

With a big old radio transformer with 5 volt, 6 volt, and 12 volt
secondaries, you have a fair amount of flexability.

On Fri, 11 Feb 2005 07:24:41 -0500, "j.b. miller"
wrote:

Get yourself a Sola 'Constant Voltage Transformer'. I got mine from as local
company 'cleaning out old junk' and it's good for about 30 Amps! Weighs
about 80 friggin' ponds( think sack of cement as big too!).
probably find them on Ebay, local colleges,electrical test shops,etc.
Any other method of stepup transformers,Variac etc will NOT be regulated
which is what I think you want. Anyone that sells Variacs should know/have
the Sola


Where are you? I've got 3 old Solas sitting under my workbench.
The buggers run warm, and being old and not perfectly clean they smell
a bit - but if you can get to Waterloo Ontario you can have one for
free.

I too have a spare CV transformer, at about the current rating you need ,
los angeles area, trade for ???
wrote in message
news
On Fri, 11 Feb 2005 07:24:41 -0500, "j.b. miller"
wrote:

Get yourself a Sola 'Constant Voltage Transformer'. I got mine from as
local
company 'cleaning out old junk' and it's good for about 30 Amps! Weighs
about 80 friggin' ponds( think sack of cement as big too!).
probably find them on Ebay, local colleges,electrical test shops,etc.
Any other method of stepup transformers,Variac etc will NOT be regulated
which is what I think you want. Anyone that sells Variacs should
know/have
the Sola


Where are you? I've got 3 old Solas sitting under my workbench.
The buggers run warm, and being old and not perfectly clean they smell
a bit - but if you can get to Waterloo Ontario you can have one for
free.