DC with AC Welder ?
Gerry Einarsson
Simple question. Anyone have any experience converting an AC [in my case
a Lincoln 225A] welder to DC operation?
Princess auto near here has 600A 1000v diodes on sale, and the thought
passed my mind that they could be used to permit DC welding if the design
doesn't get too involved.
Is half wave useable, or should a bridge be used - I'm pretty sure the
welder doesn't have a center tapped secondary.
Gerry
AZOTIC
Gerry
Its very simple to do, you just buy
4 diodes and configure them to a
full wave bridge. The transformer does
not need a center tap. You will have
to mount the diodes on a heat sink
and you will also need a fan to force
air over the heat sinks and keep the
diodes cool. Don't forget to use thermal
compound on the diodes, otherwise
you wont get good heat transfer from
the diodes to the heat sink. A small
capacitor on the d.c. output will help
to take out some of the ripple and give
you a smooth arc, also a inductor in
series with the d.c. side will make it
easier to strike the arc.
Best Regards.
Tom.
cl...@snyder.on.ca
Einarsson) wrote:
>
>
>Simple question. Anyone have any experience converting an AC [in my case
>a Lincoln 225A] welder to DC operation?
>
>Princess auto near here has 600A 1000v diodes on sale, and the thought
>passed my mind that they could be used to permit DC welding if the design
>doesn't get too involved.
>
>Is half wave useable, or should a bridge be used - I'm pretty sure the
>welder doesn't have a center tapped secondary.
>
>Gerry
Get 4 diodes and make a full wave bridge. No center tap required
jim...@hotmail.com
that inductor in series with the output had better be wound with maximum
current in mind, which means on your Lincoln about 4/0 copper (225amps)
That's some inductor!!!
There might be ways around this but I am not sure.
I am gonna build this same device (full wave bridge) for my Dayton
225amp buzz box.
I plan on using this as a supply for a TIG that I have most of the parts
for.
Also the size of capacitor must be calculated not just thrown inthere.
In building supplies years ago seems like two electrolytics could create
a synthesized center tap to a transformer that didn't normally have one.
But that was for split supplies. Oh well sorry to diverge.
In article <19990803212159...@ng-fe1.aol.com>,
azo...@aol.com (AZOTIC) wrote:
> Gerry Einarsson wrote:
>
> Simple question. Anyone have any experience converting an AC [in my
case
> a Lincoln 225A] welder to DC operation?
>
> Princess auto near here has 600A 1000v diodes on sale, and the thought
> passed my mind that they could be used to permit DC welding if the
design
> doesn't get too involved.
>
> Is half wave useable, or should a bridge be used - I'm pretty sure the
> welder doesn't have a center tapped secondary.
>
> Gerry
>
> Its very simple to do, you just buy
> 4 diodes and configure them to a
> full wave bridge. The transformer does
> not need a center tap. You will have
> to mount the diodes on a heat sink
> and you will also need a fan to force
> air over the heat sinks and keep the
> diodes cool. Don't forget to use thermal
> compound on the diodes, otherwise
> you wont get good heat transfer from
> the diodes to the heat sink. A small
> capacitor on the d.c. output will help
> to take out some of the ripple and give
> you a smooth arc, also a inductor in
> series with the d.c. side will make it
> easier to strike the arc.
>
> Best Regards.
> Tom.
>
>
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
STAN MCDONALD
The DC cheator only rectifies one half of the sign wave and therfore you
lose 1/2 the power from your welder and thus is a bad idea.
I mfg a unit that sits on on near or in your welder that gives you full
wave rectification and is a much better way to do it. Contact me off
line since I dont like to sell things via a news group seeing as some
people cry about this sort of thing.
subject ac-dc converter.
Thanks
Stan
Geoff Merryweather.
>
>
>Simple question. Anyone have any experience converting an AC [in my case
>a Lincoln 225A] welder to DC operation?
>
goto http://unix.worldpath.net/~proto/ for info on the DC Cheater,
which does what you want.
Geoff
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KD6JDJ
>
>that inductor in series with the output had better be wound with maximum
>current in mind, which means on your Lincoln about 4/0 copper (225amps)
>
>That's some inductor!!!
>
>There might be ways around this but I am not sure.
>
>I am gonna build this same device (full wave bridge) for my Dayton
>225amp buzz box.
>
>I plan on using this as a supply for a TIG that I have most of the parts
>for.
>Also the size of capacitor must be calculated not just thrown inthere.
Where do you intend to put capacitors in the TIG welder supply?
Will you use HF to start the TIG welds? If so, how do you intend to
'develop'the HF?
Jerry
prot...@my-deja.com
Stan,
Just to update you. The original DC Cheater was half-wave. We now also make
a full-wave DC Cheater in 60, 130 or 195 amp. 80% duty cycle.
Thanks,
Charlie
Joe Hovel
a full wave bridge rectifier for my AC welder, so I used 5 (!) 35 Amp
silicon bridge rectifiers in parallel - each with a 35 Amp fuse. I didn't
expect it to work, but it does! My welder can only output 140 amps, so I
have a few Amps reserve in the rectifiers. I expected one of them to have a
slightly better efficiency and draw more current and then blow the fuse,
leaving the other 4 to fight out the current among themselves and then blow
all fuses in short succession - but that has not happened....
I find the welds to be slightly easier to keep neat, but there is still far
too much ripple to call the process DC...
What size capacitor should I use to improve on this?
Also, I have a HF attachment which I put downstream of the Rectifier, but it
gives very variable results - my guess is that it needs AC to overlay it's
HF onto????? It will stop providing HF halfway through a weld or not start
the welding current on 'striking'....
Any suggestions?
KD6JDJ
>A couple of points from my experience: I couldn't find suitable diodes to do
>a full wave bridge rectifier for my AC welder, so I used 5 (!) 35 Amp
>silicon bridge rectifiers in parallel - each with a 35 Amp fuse. I didn't
>expect it to work, but it does! My welder can only output 140 amps, so I
>have a few Amps reserve in the rectifiers. I expected one of them to have a
>slightly better efficiency and draw more current and then blow the fuse,
>leaving the other 4 to fight out the current among themselves and then blow
>all fuses in short succession - but that has not happened....
If it does begin to happen, try rewiring the bridge+fuse assemblies a little
differently. Mount them so that you can connect their AC leads to the welder's
AC thru equal lengths of wire. It is expected that the equal lengths of wire
will act as 'balancing resistance'. That is -- as a bridge tries to draw more
current than the others, the voltage drop across the lead will rise, lowering
the voltage to that bridge.
>I find the welds to be slightly easier to keep neat, but there is still far
>too much ripple to call the process DC...
>What size capacitor should I use to improve on this?
I dont think that you will want to add C to the output of a stick welder.
Perhaps you can find or make an inductor to improve the output wave form.
>Also, I have a HF attachment which I put downstream of the Rectifier, but it
>gives very variable results - my guess is that it needs AC to overlay it's
>HF onto????? It will stop providing HF halfway through a weld or not start
>the welding current on 'striking'....
>Any suggestions?
#1 You may find that the bridge+ fuse assemblies will not tolerate the HV in
the HF. So, bypass caps across each diode will probably minimize that problem.
#2 I dont know how your HF attachment works. But It seems that it needs only
a little 'tweeking' to keep it running.
I'd like to know more about how to make a good (home made) HF attachment. How
do you generate the HF? What freq? Inductively coupled to the welding leads or
capacitively coupled?
Thanks Jerry
Ted Edwards
> leaving the other 4 to fight out the current among themselves and then blow
> all fuses in short succession - but that has not happened....
Scary, eh? I guess improvements in production have made them more
uniform. Also, your fuses (a *good* idea) are a series resistance to
help equalise curret. Stil...
> What size capacitor should I use to improve on this?
Use an inductor. I would guess of the order of 10mHy. A capacitor big
enough to be an effective filter at welding currents would be on the
order of 1 farad and would convert your welder to a voltage source - not
what you want.
> Also, I have a HF attachment which I put downstream of the Rectifier, but it
> gives very variable results - my guess is that it needs AC to overlay it's
> HF onto?????
That's not the problem. I have a Thermal Dynamics TIG/stick welder and
its HF works fine on both AC and DC.
Do you have any capacitors in there? Doesn't take much to short out
HF. BTW, the filter inductor should help since it will raise the
impedance seen by the HF (which must be after the inductor.
Beyond that, you've left me. I have worked with electronics for (too)
many years but not specifically with arc welders.
Ted
Joe Hovel
KD6JDJ <kd6...@aol.com> wrote in message
news:19990808112340...@ng-cd1.aol.com...
> >From: "Joe Hovel"
snip!
> >Also, I have a HF attachment
snip!
> I'd like to know more about how to make a good (home made) HF
attachment. How do you generate the HF? What freq? Inductively coupled to
the welding leads or capacitively coupled?
It is quite old and uses three spark gaps to create the HF with a couple of
coils and caps... It is inductively coupled.
I've got a circuit diagram for it here somewhere and will scan and tidy it
up for you (or anyone else). It uses a 3500V (secondary) transformer which
may be difficult to find and is obviously dangerous.... The reset of the
contents seems easy enough.
Joe
KD6JDJ
>HF attachment
> I'd like to know more about how to make a good (home made) HF
>attachment.
>Joe replied
>I've got a circuit diagram for it here somewhere and will scan and tidy it
>up for you (or anyone else). It uses a 3500V (secondary) transformer
Joe
That is what I have in the TIG that I made in the early 60s. I was hoping to
learn about some solid state technology way of making HF.
Jerry
Alan Rothenbush
>Joe Hovel wrote:
>
>> What size capacitor should I use to improve on this?
>
>Use an inductor. I would guess of the order of 10mHy. A capacitor big
>enough to be an effective filter at welding currents would be on the
>order of 1 farad and would convert your welder to a voltage source - not
>what you want.
To be a bit more specific ( and annoyingly picky ), ANY size cap would "improve"
things. However, a cap large enough to actually supply a meaningful amount of
current during the "ripple" time would be at LEAST 1 farad in size, and it seems
to me ( without redoing the calculations ) that something on the order of 10
farads or so would be required to keep the ripple under a few percent, but in
either case, this is just WAY TOO BIG a value to seriously consider.
Note that due to that pesky Ohms law applied to reactances, the inductor required
would be in the same order of magnitude to do the same thing .. that is, HENRYs
of inductance, not millihenries.
Either the cap or the inductor would result in EXACTLY the same end product, a
"smoother" voltage source, which would result in a "smoother" current flow. ( I
don't know why this is important - I'm an electronics guy who knows nothing
about welding except the phone number of his father-in-law, who does. )
Adding either would result in less PEAK current flow. Adding either would
also increase the MINIMUM current flow, ASSUMING the components were
adequately sized. Inadequately sized components would still result in current
flow reaching zero every half cycle. Average current would remain the same
under all conditions.
The only bit of good news is that BIG inductors CAN be made by a guy at home,
and in the case of a person using lots of diode bridges, he can make one inductor
per bridge. This will have several good effects. Smaller huge inductors are
easier to create than a single gianormous one, but more importantly, the inevitable
resistance of the windings will work very well to equalize the current through
the various bridges. Finally, the inductors will limit ( assuming they're big enough )
the surge current through the bridges, greatly increasing their life expectancy.
Last little bit of bad news. How much iron and copper wire will be required to
provide "smooth" - a nice subjective phrase - current flow ? ROUGHLY as much
as currently exists in your welder's transformer. OK, maybe somewhere around
1/4 to 1/2 as much, ( down to 1/10 if toroids are used for the cores ) but that
sort of order of magnitude.
Alan
Grif
house I'd like to compare it with.
> It is quite old and uses three spark gaps to create the HF with a couple of
> coils and caps... It is inductively coupled.
> I've got a circuit diagram for it here somewhere and will scan and tidy it
> up for you (or anyone else). It uses a 3500V (secondary) transformer which
> Joe
Grif
have ripple measured in .0x's% and so on,,, however, that's for a really
different type use than welding. What I'm wondering,,, what does the
minimum voltage need to be held to? (What can we get away with?) If say
the arc voltage is 10vac peak (not a clue if I'm even close) what would
get the job done during the valleys? Maby .25 volts? 1.0 volts? And,,,
for the more academic of you,,, what does the smoothed voltage do
anyway? Oxidation formation prevention? Oxidation penetration? I know
that during chrome plating they need to hold the minimum voltage up to
prevent the solution from removing the new plate,,, anyway,,, good
thread.
Grif
Wayne Cook
wrote:
In all actuality no smoothing is required at all in order to weld
with it. But the smoother the arc the easier it is to weld with, the
less spatter you get, and the smoother the bead is. That being said
I've not used a electric powered DC welder that I would consider
having a real smooth arc. Most have very noticeable ripple. Even our 3
phase powered welder at work has a relatively rough arc when compared
to something like a Lincoln Vintage (or others in that family of
gas/desiel powered DC generator welders).
BTW most welding is done in the area of 20 volts. More voltage
equals more penetration. In wire welding where you're actually
controlling the voltage instead of the amperage it's common to run
somewhere between 18 and 24 volts with some exceptions.
Wayne Cook
Shamrock TX
James W. Swonger
Wayne Cook <way...@pan-tex.net> wrote:
>On Mon, 09 Aug 1999 11:44:24 -0700, Grif <kgri...@wolfenet.com>
>wrote:
>
>>Ok,,, and I'm an electronic type as well,,, and I like my dc supplies to
>>have ripple measured in .0x's% and so on,,, however, that's for a really
>>different type use than welding. What I'm wondering,,, what does the
>>minimum voltage need to be held to? (What can we get away with?) If say
>>the arc voltage is 10vac peak (not a clue if I'm even close) what would
>>get the job done during the valleys? Maby .25 volts? 1.0 volts? And,,,
>>for the more academic of you,,, what does the smoothed voltage do
>>anyway? Oxidation formation prevention? Oxidation penetration? I know
>>that during chrome plating they need to hold the minimum voltage up to
>>prevent the solution from removing the new plate,,, anyway,,, good
>>thread
Lots of ripple can reduce arc stability. That's why square wave
TIG purports to be better to use. The sine voltage valleys are not
enough to sustain the arc, and if the arc plasma dissipates then
it has to be reestablished every cycle (this is where HF comes in).
The square wave has much, much less valley time than a sine wave.
With a buzz box you do not have a gas flow to sweep out the
plasma, so the arc does not need to be relit at every zero
crossing; you have a persistent ionization cloud around the
stick. However, this is one reason that welding outdoors
can be a bit of a pisser; too much breeze will push off
your cloud before the next half-cycle.
Open circuit on my buzz box is about 40V for high current and
80V for "maximum arc stability" output sockets. The voltage
you need to sustain the arc depends on your working distance
and steadiness. I like the higher voltage because it reduces
the required skill level to below my "stuck again, damn it!"
threshold.
If you can weld with AC, you can weld with unfiltered DC.
The valley area is exactly the same, just flipped over.
Well, minus the two diodes' deadband, but that isn't a lot.
Since stick welding is a constant current process, I don't
see a lot of reason offhand to add caps (besides which,
you need a lot of cap to make up 80V*50A*3mS worth of
charge storage, and there aren't too many caps that like
to give and receive continuous current cycling of that
magnitude).
--
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#Irresponsible rantings of the author alone. Any resemblance to persons #
#living or dead then yer bummin. May cause drowsiness. Alcohol may inten-#
#sify this effect. Pay no attention to the man behind the curtain. Billy!#
Grif
aluminum?
Paul Koning
>
> On 3 Aug 1999 22:05:02 GMT, ai...@FreeNet.Carleton.CA (Gerry
> Einarsson) wrote:
>
> >
> >
> >Simple question. Anyone have any experience converting an AC [in my case
> >a Lincoln 225A] welder to DC operation?
> >
> goto http://unix.worldpath.net/~proto/ for info on the DC Cheater,
> which does what you want.
Yes, but it seems rather expensive for 4 diodes, a heat sink, a fan,
and a case.
paul
Geoff Merryweather.
wrote:
Just like to clarify - I have no connection to the DC Cheater. I don't
even own one (almost did, but got a 130A DC Tig cheap instead). Just
thought it was a good idea, especially if youwat a ready to go
solution
Bob
watching this thread - I calculated that a 6000 mfd capacitor could deliver 100 amps at 15
volts for 1 ms, - it seems to me that even a small capacitor like this one would make a
difference to the arc - what am I missing ?
Spehro Pefhany
> I'm not an electronics expert or a welder but I do a little of both, I have enjoyed
> watching this thread - I calculated that a 6000 mfd capacitor could deliver 100 amps at 15
> volts for 1 ms, - it seems to me that even a small capacitor like this one would make a
> difference to the arc - what am I missing ?
Not much, but if you want the voltage to drop by only 5V (33%) you need to
have 3x the capacitance, say 20,000 uF. See below on the 1msec figure.
Also, most electronics grade capacitors won't much
like supplying 100A and recharging at 120Hz and will heat up and fail.
I would think 20,000 uF would make a noticable difference, but then I
don't know that much about the arc characteristics.
If you are assuming 1msec, that is 500usec on
either side of the zero crossing. A 30V peak 60Hz sine wave
( e = 30*sin(2*pi*t*f)) has a voltage of +/-5.6V at 500usec from the zero
crossing. The diodes don't help at all here, subtracting 1.5V or so.
So, maybe the 1msec is a bit optimistic too.
The fat computer grade ones with screw terminals might work, but check the
maximum ripple current rating on them! It is specified as RMS current so a
100A spike for 1msec at 120Hz is 35A RMS (unless I made a mistake).
If you really want to reduce the ripple to (say) 10%, then you would have
to put in a capacitor of size:
C= (i * t)/(delta-E) = 100 * (1/120) /(1.5) = 550,000 uF, 20X larger.
(This makes the approximation that the capacitor is supplying current for
the entire half-cycle, which *is* pretty accurate if the ripple is low.)
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany "The Journey is the reward"
sp...@interlog.com
Fax:(905) 271-9838 (small micro system devt hw/sw + mfg)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
STAN MCDONALD
If a welder went up to say 200 amps what would the new cap value be?
How does one calculate this?
volt x amps x???
or what?
Thanks
Stan
Alan Rothenbush
Spehro provides a very good answer ( saving me the trouble of all sorts of
onerous typing ) and for that I thank him. The caution of ripple current is
particularly relevant.
As a quick check of the Digikey web site, I located a Panasonic 25 volt 100,000 uf
cap. The 120 Hz ripple current of this cap is spec'd as 12.08 amps. That is, it
would melt down used in this application. At least three would be required to
handle this level of current. All of the high-capacity caps from Panasonic have
more or less this same ripple current.
At this point, ESR rears its ugly head. That same cap has an ESR of .018 ohms.
This figure limits both the maximum charge and discharge current. At any
cap voltage below 18 volts, the current will be below 100 amps, regardless of
any other external resistances.
Moreover, to ensure equal current sharing among the devices, some sort of
equalizing resistance would be required on both the input AND the output,
further decreasing charge and discharge rates.
I then located a 5600 uf low-impedence cap for comparison. This cap does
indeed have a low impedance, comparable to the big guy listed above, but its
120Hz ripple current rating is only 3.7 amps. It would get very hot indeed in this
application.
Methinks that my solution will be a WHOLE BUNCH of 35 amp bridges ( because
I have a whole bunch of them ) on a great big heatsink connected individually
to a whole bunch of .05F - .1F caps all going to common bus. ( boy, I haven't
used THAT unit - farad - in a while ) .
Then I'll connect a storage scope to the output, make some sparks and cross my
fingers. ( Again, I'm NOT a welder and BARELY a machinist, but I AM getting tired
of drilling and tapping things that really should be welded )
Alan
KD6JDJ
its output???
That will be good for wire welding some of the biggest welds that I can
imagine any home hobbiest doing. I suggest that that will be about right for
butt welding 3/4 inch thick plate, with a wirewelder And, it would be good for
nothing else, weldwise.
Jerry
referance to the posts on adding C to the output of an AC welder rectified to
provide DC.
Alan Rothenbush
I've been trying to answer the questions from an electronics standpoint, with
little welding experience, less theoretical knowledge of welding and almost
no practical knowledge.
This might be a good time for me to ASK a question, then. I wish to purchase a
welder sufficient to weld small ALUMINUM pieces, about the size and shape that
might appear on a motorcycle. This is not for bridge building, but small brackets
and jigs and whatnot. ( There might be some steel in there too, but not much )
What size of AC welder ( that I can convert to DC with the stack of surplus stuff
I have laying around ) would be suitable ? That is, how small can/should I go ?
Getting one more purchase past my wife is going to be hard enough as is, having
just taken up HSM as a hobby.
Alan
Gary Coffman
>This might be a good time for me to ASK a question, then. I wish to purchase a
>welder sufficient to weld small ALUMINUM pieces, about the size and shape that
>might appear on a motorcycle. This is not for bridge building, but small brackets
>and jigs and whatnot. ( There might be some steel in there too, but not much )
>
>What size of AC welder ( that I can convert to DC with the stack of surplus stuff
>I have laying around ) would be suitable ? That is, how small can/should I go ?
For welding small aluminum sections, you want a TIG welder which can operate
AC (or even better, squarewave). You don't TIG aluminum with DC. AC is used
because the alternating cycles provide a cleaning action to the weld which breaks
up aluminum oxide formation on one half cycle and supplies penetration on the
other half cycle. DC won't provide a satisfactory weld.
Ironically, the sort of precise current control you want for welding thin aluminum
sections generally requires a fairly large welder. Small welders don't have the
precise current control you need at low currents. Miller and Lincoln have 250 amp
machines that are suitable for use at currents below 30 amps. Cheaper machines
like the Econotig can't regulate below about 30 amps (because they don't have
enough iron in them to supply the reactance to allow the SCRs to smoothly operate
over the necessarily small conduction angles).
Inverter machines (chopper technology) with the necessary current control have
DC output, which isn't suitable for TIG welding aluminum (though it is fine for steel).
If you modified them to work AC, the AC would be too high frequency to deliver much
penetration. (Skin effect would come into play.) It would be nice if we could use one
of the small, light, and cheap import inverters that are appearing on the market, but
they just don't work for aluminum.
Now you can use a small DC MIG welder for aluminum. This works via what is
called "spray arc". It is difficult to reliably join aluminum pieces of differing sections
with this technology, however. With TIG, you could join 22 gauge material to 1/4 inch
material without much of a problem. With MIG you'd either burn holes in the thinner
section or not get any penetration of the thicker section. Aluminum has a large
heatsinking ability, you need to be able to precisely direct concentrated heat where
you need it to achieve good results. MIG is Ok for materials of approximately equal
section, but you need TIG when the thicknesses differ for the two pieces being joined.
Gary
Gary Coffman KE4ZV | You make it |mail to ke...@bellsouth.net
534 Shannon Way | We break it |
Lawrenceville, GA | Guaranteed |
KD6JDJ
>( Alan Rothenbush )
>This might be a good time for me to ASK a question, then. I wish to purchase
>a
>welder sufficient to weld small ALUMINUM pieces, about the size and shape
>that
>might appear on a motorcycle. This is not for bridge building, but small
>brackets
>and jigs and whatnot. ( There might be some steel in there too, but not much
>)
>
>What size of AC welder ( that I can convert to DC with the stack of surplus
>stuff
>I have laying around ) would be suitable ? That is, how small can/should I
>go ?
>
>Getting one more purchase past my wife is going to be hard enough as is,
>having
>just taken up HSM as a hobby.
>
Alan
I read Gary's response and think that he said all that I know, and more.
You want a TIG with AC and HF.
I understand that you have a 'big' stick welder AC welder. Do you have any
knowledge of how you can put SCRs in its primary to 'affect' the welders output
voltage? I have never seen "output control" done by SCRs in the primary, and
I've thought that SCRs dont like to control highly imductive loads. Still, that
would be a good way to approach the design of a home made TIG AC welder for
aluminum.
I can help you with a HF unit and an old torch. Where do you live? I (and my
junk) am in L.A..
Jerry
Bertho Boman
is still working fine.
1: I used big monster diodes in a bridge configuration.
2: I put 120 V Varistors across each diode to limit any wayward
transients.
3: I put a 7400uF 175 V electrolytic across the bridge output. I
happened to have it in the junk box. It is a heavy duty computer
grade type.
4: The capacitor is connected to the output via a LARGE 2.2 mH
inductor.
Several comments:
Please note that the inductor is on the output, in series with the
electrode. It's function is not to smooth the AC ripple but to act as
a current source/ high voltage trigger while an arc is struck and
burning. Without an inductor, you will have a voltage source and it
will be difficult to weld with once you put a capacitor across the
bridge.
I have seen several persons calculating the ripple but I have not seen
anyone taking into account that the bridge is feed through an
inductor, the mutual inductor of the welding transformer.
I do not believe it is so important to get low ripple. The trick is
to have sufficient current/voltage available that the arc never dies
and has to restart each half cycle.
I am sometimes using it to drive a home built carbon arc lamp and it
is amazing. No noise like an arc welder it just gently hisses which
shows that the arc is continuous.
At the time I built it, I checked the ripple under about 50 A load and
it looked very good for the application. I really do not remember the
number but my guess is 5 - 10%. Remember, we have an L-C rectifier
system, not an R-C.
Bertho Boman
Vinland Corporation
=============================================
On 11 Aug 1999 21:27:15 GMT, al...@sfu.ca ( Alan Rothenbush ) wrote:
>Bob;
>
>Spehro provides a very good answer ( saving me the trouble of all sorts of
>onerous typing ) and for that I thank him. The caution of ripple current is
>particularly relevant.
>
>As a quick check of the Digikey web site, I located a Panasonic 25 volt 100,000 uf
>cap. The 120 Hz ripple current of this cap is spec'd as 12.08 amps. That is, it
>would melt down used in this application. At least three would be required to
>handle this level of current. All of the high-capacity caps from Panasonic have
>more or less this same ripple current.
>
>At this point, ESR rears its ugly head. That same cap has an ESR of .018 ohms.
>This figure limits both the maximum charge and discharge current. At any
>cap voltage below 18 volts, the current will be below 100 amps, regardless of
>any other external resistances.
>
>Moreover, to ensure equal current sharing among the devices, some sort of
>equalizing resistance would be required on both the input AND the output,
>further decreasing charge and discharge rates.
>
>I then located a 5600 uf low-impedence cap for comparison. This cap does
>indeed have a low impedance, comparable to the big guy listed above, but its
>120Hz ripple current rating is only 3.7 amps. It would get very hot indeed in this
>application.
>
>Methinks that my solution will be a WHOLE BUNCH of 35 amp bridges ( because
>I have a whole bunch of them ) on a great big heatsink connected individually
>to a whole bunch of .05F - .1F caps all going to common bus. ( boy, I haven't
>used THAT unit - farad - in a while ) .
>
Alan Rothenbush
>For welding small aluminum sections, you want a TIG welder which can operate
>AC (or even better, squarewave). You don't TIG aluminum with DC. AC is used
>because the alternating cycles provide a cleaning action to the weld which breaks
>up aluminum oxide formation on one half cycle and supplies penetration on the
>other half cycle. DC won't provide a satisfactory weld.
Gary;
Many thanks for the reply.
The information you have provided is pretty consistent with my own
investigations.
However, in conversation with my father-in-law, a semi-retired welder,
he assures that it is possible to weld aluminum without using any gas.
I was about to argue, when he pointed out that he does it almost every
day ( he has a funny idea about what constitutes "retirement" ) for a
local firm making aluminum railings.
At this point, I started to get interested. I have a very small space that is
VERY crowded and an even more limited budget ( my #1 hobby is electronics
and #2 is woodworking - that leaves little enough coin for metalworking ).
The prospect of welding aluminum with a relatively small, inexpensive
machine is very attractive.
So, is Gord using some machine a LOT fancier than he imagines ? Or is there
some way to stick weld aluminum in a satisfactory manner ( if not pretty, at
least strong ) ?
Alan
--
Alan Rothenbush
> You want a TIG with AC and HF.
> I understand that you have a 'big' stick welder AC welder. Do you have any
>knowledge of how you can put SCRs in its primary to 'affect' the welders output
>voltage? I have never seen "output control" done by SCRs in the primary, and
>I've thought that SCRs dont like to control highly imductive loads. Still, that
>would be a good way to approach the design of a home made TIG AC welder for
>aluminum.
> I can help you with a HF unit and an old torch. Where do you live? I (and my
>junk) am in L.A..
Jerry;
Thanks to you for the reply as well. A couple of comments here ...
1. No, I don't have a stick welder yet. I have a standing offer to purchase a
good friend's for a good price. ( If he lived 30 miles closer, I wouldn't worry,
I'd just drive over, but 45 minutes each way is too far away ).
2. You're correct, if it's important to control the current relatively
precisely, the primary is certainly the easier route to go, AFTER the fact.
There is in fact another way, that is probably already in use. ( Remember,
I probably get a passing grade in electronics, but an F in welding )
By adding a small third winding to a BIG transformer and introducing a small DC
( very important, DC ) current into that winding, the magnetic field in the
transformer is disturbed and the efficiency is reduced, resulting in less output.
By controlling this small current, the large output current is easily controlled. I
would suspect that the top quality welding machines use this technique.
As a retrofit, some sort of phase control on the input could be made to work.
SCRs have no particular problems with inductive loads. The calculations
to pick an appropriate device are well understood and even GREAT BIG ones
are affordable. There are also some considerations to prevent them from
turning on at an inopportune time, but this is also well understood.
However, an SCR is not the appropriate choice for this task. A pair of SCRs,
connected "back to back" IS, but this complicates the turn-on logic slightly.
For this reason, there is the temptation to use a TRIAC, which acts very much
like a "back to back " SCR. However, TRIACs DO have problems with inductive
loads, and for that reason, are infrequently used in motor control.
The good news is that International Rectifier ( and possibly others ) have
introduced new devices that ARE basically back to back SCRs in a single
package. Electronically, they can be CONTROLLED like a TRIAC, but they
ACT like an SCR.
3. Well, I'm in Vancouver, B.C. That's a long way to drive for a good deal on
a welder. Still ...
Thanks again.
Alan
Gary Coffman
>The information you have provided is pretty consistent with my own
>investigations.
>
>However, in conversation with my father-in-law, a semi-retired welder,
>he assures that it is possible to weld aluminum without using any gas.
>I was about to argue, when he pointed out that he does it almost every
>day ( he has a funny idea about what constitutes "retirement" ) for a
>local firm making aluminum railings.
>
>At this point, I started to get interested. I have a very small space that is
>VERY crowded and an even more limited budget ( my #1 hobby is electronics
>and #2 is woodworking - that leaves little enough coin for metalworking ).
>The prospect of welding aluminum with a relatively small, inexpensive
>machine is very attractive.
>
>So, is Gord using some machine a LOT fancier than he imagines ? Or is there
>some way to stick weld aluminum in a satisfactory manner ( if not pretty, at
>least strong ) ?
I won't say it is flat out impossible, but I've never heard of anyone stick welding
aluminum. I can weld it with an oxyacetylene torch, I can TIG it, or I can spray
arc it with a MIG, but I've never heard of it being done with an ordinary stick welder.
Of course I make no claim to knowing everything about welding aluminum, or
welding in general. Perhaps he's doing submerged arc welding. That's sort of like
stick welding.
It seems to me that you have to shield the work from the air somehow. That
means you have to have a shielding gas or lots of flux. You also have to
maintain very precise temperature control because there's a very small
range between aluminum fusion and aluminum running all over the floor.
I can't control a stick welder that precisely. I haven't seen any aluminum
rods for stick welders either.
For your situation, you might consider investing on an oxyacetylene
torch outfit. You can weld steel and aluminum with that, you can *cut*
steel with it (doesn't cut aluminum worth a flip), you can braze and
solder with it, and you can heat things with it (to bend them, heat treat
them, etc). It is very versatile, and with smallish bottles, doesn't consume
a lot of space (though I'd recommend at least B size bottles). An O/A outfit
is also not very expensive (unless you're doing production work, then the
gases eat you alive). It is all I had for years.
Mike Graham
>I won't say it is flat out impossible, but I've never heard of anyone stick welding
>aluminum.
You have now. Lincoln makes a line of electrodes called "Alumaweld" and
they work pretty decently. They're used primarily for heavy castings in
non-cosmetic applications, but they work just fine. At least, they worked
fine the one time that I tried to use them. 8-)
>I can't control a stick welder that precisely. I haven't seen any aluminum
>rods for stick welders either.
You don't see them on the shelf at Home Depot. You have to ask for them
at a real welding store, and then try to convince the sales maggot that they
exist, then take the catalogue away from him and find them yourself so he
has a part number. It's almost as exciting as trying to buy a carbon-arc
torch.
--
Mike Graham, mikegraham at sprint dot ca
Caledon, Ontario, Canada (just NW of Toronto).
Raiser of animals. Weldor of metals. Driver of off-road vehicles.
Writer of FAQs. Keeper of the faith, and all around okay guy.
< homepage currently off-line due to change of ISP; back soon >
Mlnam
control. The DialArcHF 250 used a DC winding to control the primary/secondary
coupling. This was actually several very heavy windings and used a wire wound
rheostat to adjust the control current. I can still remember how hot the foot
pedal got after a few hours of use. The Syncrowave 300 and 500 use a full wave
SCR bridge to adjust output and balance (on AC) and the high frequency signal
is imposed on the welding current through a separate transformer. I haven't
seen schematics of the Syncrowave 190,250 or 350 so I don't know how the
control is accomplised in them
Richard Coke
Wayne Cook
wrote:
>On Fri, 13 Aug 1999 18:34:46 GMT, Gary Coffman wrote:
>
>>I won't say it is flat out impossible, but I've never heard of anyone stick welding
>>aluminum.
>
> You have now. Lincoln makes a line of electrodes called "Alumaweld" and
>they work pretty decently. They're used primarily for heavy castings in
>non-cosmetic applications, but they work just fine. At least, they worked
>fine the one time that I tried to use them. 8-)
>
Yes they do work ok though it would be nice to have a special lens
when running them. They also work pretty well as a torch rod when
welding thinner sections. Though one time managed to weld up a rotted
out camper type hot water heater tank with them. I was to green to
really know what I was doing but on looking back I think I used the
one technique that gave me any chance at all. I was running rather hot
(I was using a machine that was strange to me so I didn't know where
it needed to be set) and just made a lot of really quick passes with
plenty of time to cool down in between. I guess it's been about a year
since I last ran one of them (welded up a small casting that time).
>>I can't control a stick welder that precisely. I haven't seen any aluminum
>>rods for stick welders either.
>
> You don't see them on the shelf at Home Depot. You have to ask for them
>at a real welding store, and then try to convince the sales maggot that they
>exist, then take the catalogue away from him and find them yourself so he
>has a part number. It's almost as exciting as trying to buy a carbon-arc
>torch.
I can imagine. The ones I use have been at work for a lot of years.
The owner pretty much flat refuses any work that come in needing
aluminum welding (he got tired of messing with it long ago) but when
it does come in this is the only method he knows. At home I mostly use
oxy-act for doing it. I've found that the local lumber yard general
keeps the Forney brand aluminum brazing rods in stock and I've managed
some pretty tricky welds using that and a jar of some really expensive
aluminum flux I got long ago. Probably the trickiest I've done was
welding up the condenser on dad's pickup with it. Hopefully one of
these days I'll manage to get my new shop built and then get the TIG
welder I bought setup and running. Then it'll be a whole new ball game
around here (there's nobody in the area that will really touch
aluminum, at least nobody who you can catch).
Wayne Cook
Shamrock TX
KD6JDJ
>
>investigations.
>
>However, in conversation with my father-in-law, a semi-retired welder,
>he assures that it is possible to weld aluminum without using any gas.
>I was about to argue, when he pointed out that he does it almost every
>day ( he has a funny idea about what constitutes "retirement" ) for a
>local firm making aluminum railings.
>
>At this point, I started to get interested. I have a very small space that
>is
>VERY crowded and an even more limited budget ( my #1 hobby is electronics
>and #2 is woodworking - that leaves little enough coin for metalworking ).
>The prospect of welding aluminum with a relatively small, inexpensive
>machine is very attractive.
>
>So, is Gord using some machine a LOT fancier than he imagines ? Or is there
>some way to stick weld aluminum in a satisfactory manner ( if not pretty, at
>least strong ) ?
>
>
Alan
Ask Gord to take one of the small parts that you want to weld , to work and
try to weld it for you. If it is a small motorcycle part, give him one that is
not too prescious.
There is good reason to use TIG for welding aluminum. One good reason is --
it is a lot easier than the other ways.
Jerry
Gary Coffman
>On Fri, 13 Aug 1999 18:34:46 GMT, Gary Coffman wrote:
>
>>I won't say it is flat out impossible, but I've never heard of anyone stick welding
>>aluminum.
>
> You have now. Lincoln makes a line of electrodes called "Alumaweld" and
>they work pretty decently. They're used primarily for heavy castings in
>non-cosmetic applications, but they work just fine. At least, they worked
>fine the one time that I tried to use them. 8-)
Interesting. I hear you saying that this probably wouldn't be suitable for
the sorts of jobs we're talking about, however, ie small brackets, fairly
thin sections, or joining of two differing sections. It also sounds like it
takes quite a bit of skill to avoid winding up with a puddle of molten
aluminum on the floor.
>>I can't control a stick welder that precisely. I haven't seen any aluminum
>>rods for stick welders either.
>
> You don't see them on the shelf at Home Depot. You have to ask for them
>at a real welding store, and then try to convince the sales maggot that they
>exist, then take the catalogue away from him and find them yourself so he
>has a part number. It's almost as exciting as trying to buy a carbon-arc
>torch.
Hmm, been there and done that for other things. Some counter guys would
rather tell you there is no such thing than do a search for it. Thanks for telling
us about these rods. They sound like they might be useful in some situations.
Gerry Einarsson
Bertho:
This sounds exactly like the project I'm working on right now.
Don't know whether I have access to any cap's like you describe, but I
believe they are less important than the inductor in any case. Could you
describe your inductor a little more for me? Any idea where to find one,
or how to make it?
I don't think one needs to get into "ripple" calculations - the goal is to
maintain the arc - and weld with unidirectional current to aid in
deposition and control over an AC waveshape. The AC arc goes thru 0v at
each 1/2 cycle, the DC one should work as well without any filtering, but
it's operation is enhanced, as you say, if the arc doesn't actually stop.
I have located some honkin' big diodes and am assembling the bridge. The
welder is a 225 amp Lincoln, and I'm slowly getting 220 out to the garage
<grin>. Hope to be operating before winter, but the wife's projects keep
interferin'.
The varistors seem to be a good idea. Will try them myself..
Is the inductor on a core? What gauge do you think the wire is?
Thanks in advance for the assistance.....
Gerry
KD6JDJ
If you intend to build your own rectifier and reactor for welding only. I
suggest that you what the inductor will do for your ease of welding.
I submit that any C in the output of the bridge will make it more difficult
for you to strike and maintain an arc.
And, I submit that the principal value in having an inductor in series with
the welding leads is -- it will allow a higher 'striking voltage' while
lowering the arc voltage to one that you want, especially for low current
welding. Try building a series inductor using an iron core. Or, if you can
locate one, use a toroid. But, it will be a big one for 200 amps. You will
probably not need an inductor for sticks over 5/32. So, maybe you can make a
lower current series inductor for welding up to about 125 amps.
Jerry
>(Gerry Einarsson)
writes::
Glenn Neff
practical way of building one? I would think it would need to use flat wire
about 1/2" wide by 1/8" thick to pass the current but where to find tha wire??
How many henrys and what sort of Q would be needed? Most of the inductors I am
familiar with are for high voltage or RF.
In article <19990816003232...@ng-fl1.aol.com>, kd6...@aol.com
(KD6JDJ) writes:
>If you intend to build your own rectifier and reactor for welding only. I
>suggest that you what the inductor will do for your ease of welding.
> I submit that any C in the output of the bridge will make it more difficult
>for you to strike and maintain an arc.
> And, I submit that the principal value in having an inductor in series with
>the welding leads is -- it will allow a higher 'striking voltage' while
>lowering the arc voltage to one that you want, especially for low current
>welding. Try building a series inductor using an iron core. Or, if you can
>locate one, use a toroid. But, it will be a big one for 200 amps. You will
>probably not need an inductor for sticks over 5/32. So, maybe you can make a
>lower current series inductor for welding up to about 125 amps.
>
Glenn Neff
Medford OR
KD6JDJ
Wrote
>Where would one look to find such an inductor
I picked mine out of an old , military power supply. It uses flat 1 inch by .25
inch copper. It is about 10 in by10 in by 3 in laminated iron core.
or where would one look to find
>a
>practical way of building one? I would think it would need to use flat wire
>about 1/2" wide by 1/8" thick to pass the current but where to find tha
>wire??
>How many henrys and what sort of Q would be needed? Most of the inductors I
>am
>familiar with are for high voltage or RF.
Id say that you wont have to wory about getting too many henrys. Just make
one, and try it. It wont help much, except for welding with low current.
Jerry
Eastburn
It will then be a 300 cu.in. (rough) core. SO find a scrap transformer in
about that volume - A nice heavy H frame (really an "8" to me.) wind on the
center.
The outside 'loops' of the core wrap the magnetic field back to the core -
Stronger coupling - stronger level of inductance.
No need for silver plated windings :) - never hurts if you have it...
To bad the number of wraps isn't mentioned (turns)... ?
Martin
--
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder
Martin Eastburn, Barbara Eastburn
@ home on our computer old...@pacbell.net
Bertho Boman
inches. The wire looks like 1/4" square. My guess is 3 layers of 15
turns for a total of 45. It measured 2.2 mH.
Again, let me repeat that it is not for ripple reduction. It is to
get a high impedance output for the arc. It will burn smoothly when
there is inductive energy storage in series with the electrode.
The shunt ripple reducing capacitor is exactly opposite. It makes it
difficult to maintain an arc since it now will become a constant
voltage system instead of a constant current one.
Someone suggested that adding the inductor will not make a big
difference. That is true if there is no storage capacitor since at
that time the leakage inductance of the welding transformer acts as an
series inductor. That is what it was designed for.
Where to find an inductor? Look for industrial surplus. I found it
in my junk box (it is a big junk box since I am a super pack rat)
For temporary welding, get a heavy duty "extension cord" and unplug
your stove and you have a 50 amp outlet available between meals.
By the way, your last name sounds Swedish. Am I right?
Good Luck,
Bertho Boman
===========================================
On 16 Aug 1999 03:00:50 GMT, ai...@FreeNet.Carleton.CA (Gerry
Gerry Einarsson
Wheelin' the stove in and out is gonna stimulate some quality matrimonial
conversation I 'spect, unless it's really occasional use <VBG>, but thanks
for the idea.
Nope, the name's Icelandic - that close enough? We're into planning an
Icelandic celebration in Canada next year - celebrating the millennium
anniversary of the first europeans arrival in North America - an
Icelander, of course. Chris missed it by almost 500 years <grin>. No
offence intended....
Your analysis appeared the most logical I've heard re the DC welding
question, but I'm still thinking about the capacitor. As you probably
guessed, I had decided to go with the inductor alone, as I didn't think
the cap added much in reality. This post of yours suggests it's
necessary. Am I correct in that?
Thanks
Gerry
Bertho Boman
voltage will go to zero 120 times per second. At that time the arc
will go out and must restart again when the voltage gets sufficiently
high. It starts easily because of the extremely hot electrode and
weld puddle and ionized gases floating around. The sound will be
noisy with the 120 Hz interruptions. It will work just fine.
With the capacitor, the arc burns continuously and is strangely quiet
and will work a little better. Significant? I do not know.
The world is small after all. Icelandic is close enough to Swedish.
There are good reason for the name of my company: Vinland Corporation
and I also have a son named Leif.
For the people whose viking history is not up to date: Vinland is the
old viking name for North America and it was Leif Eriksson that
discovered it just about 1000 years ago and started a settlement in
Newfoundland.
Bertho Boman
A transplant from cold Sweden to hot Florida
==============================================
Ted Edwards
> Without the capacitor, you will have full wave rectified AC and the
> voltage will go to zero 120 times per second. At that time the arc
Have you actually tried this? According to my calcs, the cap would have
to be truly humogeous while an inductor sounds reasonable. Have you
actually tried inductor plus cap vs. inductor only?
> On 17 Aug 1999 ai...@FreeNet.Carleton.CA (Gerry Einarsson) wrote:
> >Nope, the name's Icelandic - that close enough?
My wife's name is Birtna. Guess where she was born.
> >We're into planning an Icelandic celebration in Canada next year - celebrating the millennium
Whre is this?
Ted
KD6JDJ
>
>> Without the capacitor, you will have full wave rectified AC and the
>> voltage will go to zero 120 times per second. At that time the arc
>
>Have you actually tried this? According to my calcs, the cap would have
>to be truly humogeous while an inductor sounds reasonable. Have you
>actually tried inductor plus cap vs. inductor only?
If you want to make a MIG power source, put about a farad of C across the
rectifier output. Otherwise dont. Capacitance across the rectifier output will
make it much more difficult to stick weld and essentially impossible to TIG.
Jerry
jim...@hotmail.com
I wish all the welding situations could be done with just one machine
but after consideration two is minimum.
considering
a mig is a mig is a mig.
a a/c stick is that and
rectified and filtered it is a source supply for anything else
what 30 odd volts at 200 plus amps in either DCRP or other.
not to beat a dead or dying horse but it is the building and
implementing the (TIG)high frequency unit that isn't clear.
Did anyone ever come up with any schematics or tech docs concerning this
?
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.
jim...@hotmail.com
Bertho Boman
As I said a few messages back, I built it about 15 years ago and it is
still working. At that time, I tried it without the capacitor and the
arc was noisy (120 Hz interruptions). I then added the capacitor and
it was quite and continuously burning.
Since there is so much interest and doubt about the performance of the
system, I fired it up again a few minutes ago and connected
instrumentation to measure its performance.
The 230 Amp AC Sears arc welder was set on 100 Amps on "A" scale.
The arc load was a home built carbon arc lamp using 3/8" and 1/2"
copper coated electrodes in an adjustable feed configuration. The
light output is focused through a 12" x 12" fresnel lens.
The AC current to the rectifiers was measured with an AC clamp on
meter (Radio Shack)
The DC current to the lamp was measured with an precision HP clamp on
meter.
The arc voltage was monitored by both an analog voltmeter and an
digital multi meter
The ripple voltage was measured in both peak to peak and RMS value
with a Tektronix scope and with a DVM to measure RMS ripple.
Measurement results:
The AC current read about 115 A RMS when the DC current read 98 Amps.
I did not check the AC waveform and the accuracy of the Radio Shack
meter is unknown but the HP DC reading should be more accurate and
interestingly, it agreed very well with the setting of the welder.
I adjusted the electrode distance for an arc voltage for 30 VDC and
then measured the RMS and peak to peak ripple. Both scopes and meters
agreed on the following results.
Ripple @ 98 Amps= 0.5 VRMS and 1.6 Vp-p
The key to the success is the L-C rectifier circuit. The rectifiers
are feed from the welding transformer through the internal series
inductor= variable inductance of the arc welder. At the 100 Amp "A"
scale setting it is at its maximum value. The ripple will increase if
the current is increased since the inductor value will be decreased.
For a while, I cranked it up to max current but I can not easily take
measurements at that level. The paint just about will catch fire on
the wall where the lamp is focused (200 amps x 30 V= 6 KW). I also
got a sun burn.....
Take Care,
Bertho
============================================
Bertho Boman
A capacitor across the output is terrible. I said so in one of my
previous comments.
The capacitor must be followed by the inductor so the welding
electrode is connected to the inductor, not the capacitor.
Bertho
=============================
Ted Edwards
> arc was noisy (120 Hz interruptions). I then added the capacitor and
> it was quite and continuously burning.
Interesting post. Thanks for the info. I had (apparently mistakenly)
got the impression that you were arc welding not arc lighting. Would
this not make a difference?
Ted
Gerry Einarsson
It's a little spread out guys. In Newfoundland - L'Anse aux Meadows, there
will be a ceremony with a landing of a replica Viking boat, in Ottawa
there will be a statue presented by the Prime Minister of Iceland
to Canada at the Museum of Civilization, and possibly the opening of an
Embassy, in Winnipeg / Gimli etc there will be a celebration honoring the
125th anniversary of the Icelandic immigration to the interlake region,
etc.
I believe that there will be some involvement with respect to the
Icelandic communities in the Dakotas, since quite a number immigrated
there, and moved between Manitoba and North Dakota. There is something
planned for Wynyard, Saskatchewan, Kinmount Ontario, and a few locations
in Alberta and BC. Watch for thew Icelanders near you....coming soon <grin>.
Perhaps this is a little OT for this group [although I'm never surprised
at the diversity of interests shown here], so if people would like me to take
this off line, I'll post updates to those interested by e-mail. What do
you think?
Regards
Gerry
>
> Ted Edwards (Te...@bc.sympatico.ca) writes:
>> Bertho Boman wrote:
>>
>>> Without the capacitor, you will have full wave rectified AC and the
>>> voltage will go to zero 120 times per second. At that time the arc
>>
>> to be truly humogeous while an inductor sounds reasonable. Have you
>> actually tried inductor plus cap vs. inductor only?
>>
Bertho Boman
Bertho Boman
Vinland Corporation
Florida
================================
Gerry Einarsson
You're on my update list Bertho.
By the way, the Icelanders don't seem to have *all* the action. I noticed
that the Royal Canadian Mint is making a commemmorative coin cooperatively
with the Norwegians - while worth $5.00. it'll cost $36.00 I think for the
mint set.
Gerry
Bertho Boman
It is difficult to weld and measure at the same time! Also the
welding current & voltage tends to fluctuate because of hand movement,
at least when I weld which makes it more difficult to get accurate
data.
The theory and end result should be very close between arc welding and
arc light. For the measurements, I just pull an arc between two
electrodes instead of between one electrode and the work piece.
Currents and voltages are similar.
Bertho
==================================