I tried posting this earlier, but I got an error message when I went to
post it. So, I am not sure the first message went anywhere. If this is
a double post, I apologize.

I am attempting to build a resistance soldering unit from a small car
battery charger. I am following these directions:

http://www.trainweb.org/girr/tips/tips1/solderer.pdf

I am using a 12v 6a charger that, I think, is too small. I can just get
two pieces of .005 brass sheet soldered together before the charger
circuit breaker shuts off the charger. The charger will run for about
6-7 seconds. This should heat it up within 3 seconds. I would like to
solder up to around .025 brass sheets together too. I found a 12/30/75
amp charger at Menards that is probably my next step. But I would like
to be able to vary the current coming out. Do I need a variac for this?
Does this go on the input (110v) or the output (12v) side of the
charger? What specs (volts/amps/watts) should I look for on this? I
also know that I could use a filament transformer of around 6.3v 6-20
amps on the secondary in place of the battery charger. Any suggestions
on which is better? I KNOW that using a light dimmer switch for the
adjustment setting is a bad idea.

I already know that American Beauty and PBL sells these. But for around
$500 for a 250 watt model, I think I will screw around with this some
more. I am bidding on a 300 watt model on ebay right now.

I also searched around the Internet for more instructions. But
everything I found was pretty vague. I am electronics illiterate, but I
can usually figure stuff out with some clear directions.

ANY help on this would be greatly appreciated.

THANKS!

Mike

On 1 Jan 2006 13:06:45 -0800, "mj" wrote:

I tried posting this earlier, but I got an error message when I went to
post it. So, I am not sure the first message went anywhere. If this is
a double post, I apologize.

I am attempting to build a resistance soldering unit from a small car
battery charger. I am following these directions:

http://www.trainweb.org/girr/tips/tips1/solderer.pdf

I am using a 12v 6a charger that, I think, is too small. I can just get
two pieces of .005 brass sheet soldered together before the charger
circuit breaker shuts off the charger. The charger will run for about
6-7 seconds. This should heat it up within 3 seconds. I would like to
solder up to around .025 brass sheets together too. I found a 12/30/75
amp charger at Menards that is probably my next step. But I would like
to be able to vary the current coming out. Do I need a variac for this?
Does this go on the input (110v) or the output (12v) side of the
charger? What specs (volts/amps/watts) should I look for on this? I
also know that I could use a filament transformer of around 6.3v 6-20
amps on the secondary in place of the battery charger. Any suggestions
on which is better? I KNOW that using a light dimmer switch for the
adjustment setting is a bad idea.

I already know that American Beauty and PBL sells these. But for around
$500 for a 250 watt model, I think I will screw around with this some
more. I am bidding on a 300 watt model on ebay right now.

I also searched around the Internet for more instructions. But
everything I found was pretty vague. I am electronics illiterate, but I
can usually figure stuff out with some clear directions.

ANY help on this would be greatly appreciated.

THANKS!

You're not getting nearly enough current from a small battery charger.
One 500-watt resistance soldering box (Wassco Glo-Melt model 105-B2)
has voltage taps from 1.0 to 5.8 volts -- which, at 500 watts would be
500 to 86 amps.

You might try a soldering gun --without the tip. My (old) Weller
D-550 delivers 240 or 325 watts at 1.5 volts. That's 160 and 216 amps
-- if the load resistance is low enough to accept it. There's one
;ike it on EBay right now:

http://cgi.ebay.com/ws/eBayISAPI.dll...y=46 413&rd=1

Looks like current production D550's are rated at 260/200 watts.
The D650 is rated at 300/200 watts. You might also try a 150 from
HF( item 42685) for $9.99. You could use two or more in series or
parallel to get more heat.

The tubes on the Weller are threaded 7/16-14 so you could connect to
it with a couple of bolts. Use very heavy wire like #4 welding
cable, automotive ground braid or copper strip for (short)
connections from soldering gun to work and stinger. The issue isn't
overheating the wire, but minimizing voltage drop everywhere but in
the load itself.

Yes, a variac would be the best control. With a variac, I'd tape the
trigger down on the gun and use the variac to control it. A foot
switch might be handy too.

Hi Don,
Yeah...I had thought about using a soldering gun for the power pack.
But I sort of like the portability of the soldering iron that I already
have built. I have a foot control, but it is a simple momentary ON
(while the pedal is to the metal) or Off (foot off the pedal). The
thing is, this setup works. I am just not getting the current I need at
the end of the carbon. I am hoping to get some more replies before I
throw more money at this. I "think" a larger charger with a variac will
work. If you don't mind taking a look at this auction, I am looking at
this variac:

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1

This would go on a 12/30/75 amp charger something like this one from
Amazon:

http://www.amazon.com/gp/product/B00...nce&n=15684181

One of the things that I don't understand (I don't understand a lot of
what I am doing, this is only one of them) is which side does this go
on? The 110v or the 12v side? My guess is the 110v side.

Thanks for the reply.

Mike

Definitely on the primary (110v) side. Just remember that the Variac does
NOT isolate the output from the 110v input. I'm sure your aware but thought
I'd mention it. The output of the soldering gun would be AC but the
charger, of course, is DC. I had considering building one but also using a
DC cap in the circuit to give it just a bit more "punch". I've not looked
inside one of the commercial units to verify if those are done that way or
not.
Respectfully,
Ron Moore

"mj" wrote in message
ups.com...
Hi Don,
Yeah...I had thought about using a soldering gun for the power pack.
But I sort of like the portability of the soldering iron that I already
have built. I have a foot control, but it is a simple momentary ON
(while the pedal is to the metal) or Off (foot off the pedal). The
thing is, this setup works. I am just not getting the current I need at
the end of the carbon. I am hoping to get some more replies before I
throw more money at this. I "think" a larger charger with a variac will
work. If you don't mind taking a look at this auction, I am looking at
this variac:

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1

This would go on a 12/30/75 amp charger something like this one from
Amazon:

http://www.amazon.com/gp/product/B00...nce&n=15684181

One of the things that I don't understand (I don't understand a lot of
what I am doing, this is only one of them) is which side does this go
on? The 110v or the 12v side? My guess is the 110v side.

Thanks for the reply.

Mike

On 1 Jan 2006 16:41:37 -0800, "mj" wrote:

Hi Don,
Yeah...I had thought about using a soldering gun for the power pack.
But I sort of like the portability of the soldering iron that I already
have built. I have a foot control, but it is a simple momentary ON
(while the pedal is to the metal) or Off (foot off the pedal). The
thing is, this setup works. I am just not getting the current I need at
the end of the carbon. I am hoping to get some more replies before I
throw more money at this. I "think" a larger charger with a variac will
work. If you don't mind taking a look at this auction, I am looking at
this variac:

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1

That'll work.

This would go on a 12/30/75 amp charger something like this one from
Amazon:

http://www.amazon.com/gp/product/B00...nce&n=15684181

Uh....I think you're right to wait for more replies.

One of the things that I don't understand (I don't understand a lot of
what I am doing, this is only one of them) is which side does this go
on? The 110v or the 12v side? My guess is the 110v side.

Right.

On Sun, 1 Jan 2006 19:51:46 -0600, "Ron Moore"
wrote:

Definitely on the primary (110v) side. Just remember that the Variac does
NOT isolate the output from the 110v input. I'm sure your aware but thought
I'd mention it. The output of the soldering gun would be AC but the
charger, of course, is DC. I had considering building one but also using a
DC cap in the circuit to give it just a bit more "punch". I've not looked
inside one of the commercial units to verify if those are done that way or
not.
Respectfully,
Ron Moore

They're not. They're AC. AC heats just as well as DC, why rectify
it?

You're right that DC with a cap would have more punch -- if you want
divots in your sheetmetal.

I was thinking of the welder mech that is used to link batteries into packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger. Once again, my mind was on the wrong box. Great article
on the shopbuilt resistance soldering device. I may have to build one, just
to have one in case..... The Variac would be great to control current,
especially with the soldering gun, which may be too much anyway. Sorry
about my confusion.
Respectfully,
Ron Moore



"Don Foreman" wrote in message
...
On Sun, 1 Jan 2006 19:51:46 -0600, "Ron Moore"
wrote:

Definitely on the primary (110v) side. Just remember that the Variac does
NOT isolate the output from the 110v input. I'm sure your aware but
thought
I'd mention it. The output of the soldering gun would be AC but the
charger, of course, is DC. I had considering building one but also using
a
DC cap in the circuit to give it just a bit more "punch". I've not looked
inside one of the commercial units to verify if those are done that way or
not.
Respectfully,
Ron Moore

They're not. They're AC. AC heats just as well as DC, why rectify
it?

You're right that DC with a cap would have more punch -- if you want
divots in your sheetmetal.

Interesting idea, I never thought of that approach. Have you done this and
did it work?? How well compared to a commercial unit like the American
Beauty??

You might try a soldering gun --without the tip. My (old) Weller
D-550 delivers 240 or 325 watts at 1.5 volts. That's 160 and 216 amps
-- if the load resistance is low enough to accept it. There's one
;ike it on EBay right now:

You would use the variac on the 120 v side of the stepdown transformer so
it is feeding thtransformer a variable input voltage. Never on the output.

That said, you are still taking the wrong approach, the transformer in that
battery charger is still to high a voltage output and to low a current. You
want like a big asses old4-5 v filament transformer with a 100 amp output!!

On 1 Jan 2006 13:06:45 -0800, "mj" wrote:

I would like to
solder up to around .025 brass sheets together too. I found a 12/30/75
amp charger at Menards that is probably my next step. But I would like
to be able to vary the current coming out. Do I need a variac for this?
Does this go on the input (110v) or the output (12v) side of the
charger? What specs (volts/amps/watts) should I look for on this? I
also know that I could use a filament transformer of around 6.3v 6-20
amps on the secondary in place of the battery charger. Any suggestions
on which is better? I KNOW that using a light dimmer switch for the
adjustment setting is a bad idea.

On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore"
wrote:

I was thinking of the welder mech that is used to link batteries into packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger.

Right, it's the resistance soldering device, soldering guns and
otherwise. The Wassco I mentioned is also AC. Capacitive discharge
DC works great for spotwelding batteries.

Gunner has mentioned soldering heavy wires by pressing a 250-watt gun
(sans tip) up against the splice and pulling the trigger, using the
current to heat the wires. I've never tried that, but it sounds
neat. The tip on a 250 watt gun is a few inches of about 1/8"
square copper and it get real hot right quick.

I do that all the time. I have to solder the center pins on coax connectors
and have 2 notches filed in the part of the gun the tip attaches to. Just
stuff the pin in and pull the trigger about 2 sec and it is melting solder.
Slip it over the end of the wire and pull the trigger again and it is a done
deal. The pins stick in the gun tight enough that when you pull the gun off
it tests the connection too. I have also used it to solder car battery
cables etc. but you have to remove the tip for that.
My PACE Kit has resistance soldering tweezers that are wonderful for DB
connectors. The wire leads in those is about 14GA. I have never measured
the voltage and current in it though.

Glenn

"Bradford Chaucer" wrote in message
...
Interesting idea, I never thought of that approach. Have you done this
and
did it work?? How well compared to a commercial unit like the American
Beauty??

You might try a soldering gun --without the tip. My (old) Weller
D-550 delivers 240 or 325 watts at 1.5 volts. That's 160 and 216 amps
-- if the load resistance is low enough to accept it. There's one
;ike it on EBay right now:

On Mon, 02 Jan 2006 05:25:52 GMT, Bradford Chaucer
wrote:

Interesting idea, I never thought of that approach. Have you done this and
did it work?? How well compared to a commercial unit like the American
Beauty??

You might try a soldering gun --without the tip. My (old) Weller
D-550 delivers 240 or 325 watts at 1.5 volts. That's 160 and 216 amps
-- if the load resistance is low enough to accept it. There's one
;ike it on EBay right now:

I haven't, and I don't have an American Beauty to compare it to -- but
I do have an old 500-watt Wassco. I use a little O/A torch for
silverbrazing small stuff, but I certainly do a resistance soldering
experiment if you'd care to define the experiment.

Gunner has soldered wires together by pressing a soldering gun (sans
tip) against a splice to be soldered.

My priority job right now is to fix the Reznor unit heater in my
shop that doesn't wanna light off until I smack it with a pipe.
I think it needs a new gas valve or gas valve controller after a mere
20 years of service. I thought it just needed a new thermocouple --
until I discovered that it doesn't even use a thermocouple. Uses
flame rectification for flame proving and that seems to be working
because the ignitor quits sparking once the pilot is lit.

Unnnnggghhh. Wanna fixit before it gets cold in MN. A cold shop
is not a happy shop.

Hi Bradford,
Actually from what I've read on using a filament transformer is that a
6.3 v with anywhere from 6-20 amps is "supposed" to work. I don't know
how well this concoction is going to work compared to a commercial
unit, but I am willing to throw around $100 at it to find out.

I am looking around for a filament transformer on ebay. Unless you have
an old tube type TV set that you could pull one out for me. LOL.

Earlier you had asked how this setup compares to an American Beauty. I
don't know. I've never gotten my hands on an AB or any other commercial
units for that matter. The one that I am looking at from PBL is a 300
watt unit. From my rudimentary electronics knowledge, a 6v (or there
abouts) transformer with even 20 amps on the output is 120 watts,
correct? (6 x 20). Your idea of using a 4-5 volt / 100 amp output would
get me up to 400-500 watts. Where I would find something that big, I
have no idea.

Mike

Bradford,
My unit works...sort of. It ran long enough to get two pieces of .005
brass sheet strips soldered together before the internal breaker kicked
in. It takes a little bit for it to cool before I could try it again.
Even soldering the .005 strips took about 5-6 seconds. The commercial
units will do it in about 3. I just need more power coming out of the
carbon rod, which I "think" is more amps and maybe lower volts.
Mike

That's right, lower voltage, higher current. When the voltage is too high,
you will just get arcing and pitting of the parts and electrodes.

As to transformers, keep poking about on Ebay. I picked up some a while
back.

On 2 Jan 2006 03:25:24 -0800, "mj" wrote:

Bradford,
My unit works...sort of. It ran long enough to get two pieces of .005
brass sheet strips soldered together before the internal breaker kicked
in. It takes a little bit for it to cool before I could try it again.
Even soldering the .005 strips took about 5-6 seconds. The commercial
units will do it in about 3. I just need more power coming out of the
carbon rod, which I "think" is more amps and maybe lower volts.
Mike

Do a search on Microwave Oven Transformers in RCM. A typical MWO
transformer is good for about 1000 watts. The secondary is fairly easy
to remove and a new secondary can be wound on. You get about one volt
per turn so you don't have to have many turns.

I can find Mircowave Ovens for two or three dollars at the St. Vincent
de Paul that are guaranteed to be defective. I have only purchased
two, but both of those had good transformers.


Dan

In article ,
Don Foreman wrote:

On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore"
wrote:

I was thinking of the welder mech that is used to link batteries into packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger.

Right, it's the resistance soldering device, soldering guns and
otherwise. The Wassco I mentioned is also AC. Capacitive discharge
DC works great for spotwelding batteries.

Gunner has mentioned soldering heavy wires by pressing a 250-watt gun
(sans tip) up against the splice and pulling the trigger, using the
current to heat the wires. I've never tried that, but it sounds
neat. The tip on a 250 watt gun is a few inches of about 1/8"
square copper and it get real hot right quick.

I recently measured the voltage across the tip of my 250-watt Wen
soldering gun - it's 0.175 volts rms or so (starts lower, then rises as
the copper tip heats and increases in resistance). To achieve the
stated 250 watts, the current will be 250/0.175= 1,429 amps. This could
almost be used for spot welding (where 4,000 amps is more common), and
the resulting magnetic field can pick up small pieces of iron (~50
grams).

For the record, the Wen Soldering Gun (Model 250, bought in 1963)
consists of a big AC power transformer with a one-turn secondary made of
3/8 inch brass rod. The open-circuit voltage (with tip removed) is
0.275 volts rms, for 118.9 volts rms in, so the transformer winding
ratio is 435:1. The gun was manufactured under US patents 2,701,835 and
2,680,187. Go to http://www.pat2pdf.org/ to get copies.

The Weller soldering gun is almost identical, although the tip of the
Wen is instead made of 0.164" diameter (~AWG #6) plated round copper
wire.

Joe Gwinn

On Mon, 02 Jan 2006 12:07:02 -0500, Joseph Gwinn
wrote:

In article ,
Don Foreman wrote:

On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore"
wrote:

I was thinking of the welder mech that is used to link batteries into packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger.

Right, it's the resistance soldering device, soldering guns and
otherwise. The Wassco I mentioned is also AC. Capacitive discharge
DC works great for spotwelding batteries.

Gunner has mentioned soldering heavy wires by pressing a 250-watt gun
(sans tip) up against the splice and pulling the trigger, using the
current to heat the wires. I've never tried that, but it sounds
neat. The tip on a 250 watt gun is a few inches of about 1/8"
square copper and it get real hot right quick.

I recently measured the voltage across the tip of my 250-watt Wen
soldering gun - it's 0.175 volts rms or so (starts lower, then rises as
the copper tip heats and increases in resistance). To achieve the
stated 250 watts, the current will be 250/0.175= 1,429 amps. This could
almost be used for spot welding (where 4,000 amps is more common), and
the resulting magnetic field can pick up small pieces of iron (~50
grams).

For the record, the Wen Soldering Gun (Model 250, bought in 1963)
consists of a big AC power transformer with a one-turn secondary made of
3/8 inch brass rod. The open-circuit voltage (with tip removed) is
0.275 volts rms, for 118.9 volts rms in, so the transformer winding
ratio is 435:1. The gun was manufactured under US patents 2,701,835 and
2,680,187. Go to http://www.pat2pdf.org/ to get copies.

The Weller soldering gun is almost identical, although the tip of the
Wen is instead made of 0.164" diameter (~AWG #6) plated round copper
wire.

Joe Gwinn

Joe is right. I'd assumed 1.5 volts because it illuminates the
little penlight bulbs, but my measurement just now agrees with Joe's.
They must have another winding for the light bulbs.

Thanks, Joe!

Rather than buy a battery charger, I suggest the two courses most
likely to work a

1: Dan Caster's suggestion of putting a new secondary on a
discarded microwave oven. If the size and weight aren't a problem,
that would certainly work. (Be sure to strip the high voltage
secondary off completely. ) Make that 1 or 2 turn secondary out of
insulated heavy braid or copper strip, or several (half a dozen)
bits of #12 copper wire in parallel.

2: buy two or three HF soldering guns at $9.99 each, connect them in
series. 0.175 volts may not be enough to push much current thru thin
brass.

Neither of these courses will cost half as much as the battery
charger, and both are much more likely to work.

Don Foreman wrote:
On Mon, 02 Jan 2006 12:07:02 -0500, Joseph Gwinn
wrote:


In article ,
Don Foreman wrote:


On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore"
wrote:


I was thinking of the welder mech that is used to link batteries into packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger.

Right, it's the resistance soldering device, soldering guns and
otherwise. The Wassco I mentioned is also AC. Capacitive discharge
DC works great for spotwelding batteries.

Gunner has mentioned soldering heavy wires by pressing a 250-watt gun
(sans tip) up against the splice and pulling the trigger, using the
current to heat the wires. I've never tried that, but it sounds
neat. The tip on a 250 watt gun is a few inches of about 1/8"
square copper and it get real hot right quick.

I recently measured the voltage across the tip of my 250-watt Wen
soldering gun - it's 0.175 volts rms or so (starts lower, then rises as
the copper tip heats and increases in resistance). To achieve the
stated 250 watts, the current will be 250/0.175= 1,429 amps. This could
almost be used for spot welding (where 4,000 amps is more common), and
the resulting magnetic field can pick up small pieces of iron (~50
grams).

For the record, the Wen Soldering Gun (Model 250, bought in 1963)
consists of a big AC power transformer with a one-turn secondary made of
3/8 inch brass rod. The open-circuit voltage (with tip removed) is
0.275 volts rms, for 118.9 volts rms in, so the transformer winding
ratio is 435:1. The gun was manufactured under US patents 2,701,835 and
2,680,187. Go to http://www.pat2pdf.org/ to get copies.

The Weller soldering gun is almost identical, although the tip of the
Wen is instead made of 0.164" diameter (~AWG #6) plated round copper
wire.

Joe Gwinn


Joe is right. I'd assumed 1.5 volts because it illuminates the
little penlight bulbs, but my measurement just now agrees with Joe's.
They must have another winding for the light bulbs.

Thanks, Joe!

Rather than buy a battery charger, I suggest the two courses most
likely to work a

1: Dan Caster's suggestion of putting a new secondary on a
discarded microwave oven. If the size and weight aren't a problem,
that would certainly work. (Be sure to strip the high voltage
secondary off completely. ) Make that 1 or 2 turn secondary out of
insulated heavy braid or copper strip, or several (half a dozen)
bits of #12 copper wire in parallel.

2: buy two or three HF soldering guns at $9.99 each, connect them in
series. 0.175 volts may not be enough to push much current thru thin
brass.

Neither of these courses will cost half as much as the battery
charger, and both are much more likely to work.


My rapidly disappearing short term memory may be causing me repeat this
here, but a soldering gun also makes an ersatz demagnetizer for stuff
small enough to fit inside the loop formed by the tip, like say a
screwdriver. Just remember to move the steel part away before releasing
the trigger.

My rapidly disappearing short term memory may be causing me repeat this
here, but a soldering gun also makes .... Aw, ****e!

Happy New Year!

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

I've heard of doing this too. And I might have access to an old
microwave. The one in our kitchen needs to be replaced one of these
days. This might be a good excuse to replace it.

Then all I need to do is figure out how to rewire the secondary....

But I am sure you guys will be able to explain that to me LOL.

Thanks
Mike

I remember reading something about using a microwave transformer when I
was earlier researching this on the web. I sort of lost interest when
it got to the part of rewinding the secondary.

But...I have an old microwave in the kitchen that we are going to
replace one of these days. Other than the cost of a new microwave to
replace the old one (which we are going to HAVE to do sooner or later),
the part is practically free and only sitting about 20 feet from me.

I'll probably be back with a zillion dumba** questions on rewinding
this thing. LOL.

Thanks for all the replies on this too!

Mike

Hey Dan,
Wow...there is a lot of information on MWO transformers. The one that
gave me the fuzziest feeling was this one:

Quote text:
I have a microwave transformer from a 600 W oven. This is very confusing to
me because the power in side has the standard two lead connection. The part
that puzzles me is, the out side has three connections. Which connections
are the ones I should use?

DANGER! WARNING! Microwave oven transformers make lethal voltages.
If you don't know what you are doing (and from the above, you don't),
please don't screw around with them.

[Normally I'd say Google is your friend, but in this case it'll give
you just enough information to kill yourself or some innocent
bystander.]
Unquote text

Good golly this looks like fun! There was another posting on how I only
need to be within inches of it for the volts to just jump out and
attack me.

Are these things really that lethal?

Mike

According to mj :
Hi Bradford,
Actually from what I've read on using a filament transformer is that a
6.3 v with anywhere from 6-20 amps is "supposed" to work. I don't know
how well this concoction is going to work compared to a commercial
unit, but I am willing to throw around $100 at it to find out.

I am looking around for a filament transformer on ebay. Unless you have
an old tube type TV set that you could pull one out for me. LOL.

Most tube type TV sets had series-connected filaments which
added up to 115 VAC. There would be a filament supply for the CRT, but
IIRC, that was derived off of the flyback transformer for high-voltage
isolation.

What you really want is a transformer for a serious transmitter,
broadcast style. The final output tubes tended to have their own
filament transformers, separate from the HV transformers, and those tube
filaments ran at quite high current and quite low voltage -- just what
you need.

Earlier you had asked how this setup compares to an American Beauty. I
don't know. I've never gotten my hands on an AB or any other commercial
units for that matter. The one that I am looking at from PBL is a 300
watt unit. From my rudimentary electronics knowledge, a 6v (or there
abouts) transformer with even 20 amps on the output is 120 watts,
correct? (6 x 20). Your idea of using a 4-5 volt / 100 amp output would
get me up to 400-500 watts. Where I would find something that big, I
have no idea.

Old filament transformers for broadcast transmitter tubes.

I suspect that those are still made.

Enjoy,
DoN.
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According to mj :

[ ... dangers of microwave transformers ... ]

Good golly this looks like fun! There was another posting on how I only
need to be within inches of it for the volts to just jump out and
attack me.

Are these things really that lethal?

As is -- pretty close. Though I don't think that they actually
get *that* high in output voltage.

But -- once you strip off the secondary (finer wire), you should
be fine. It is that secondary which creates the high voltages. You'll
be replacing the secondary with only one or two turns, I think. And you
want *heavy* wire for those turns.

That original web page which you posted really was worrying me
about some of his techniques. And -- by the time I read to the end, I
discovered that he was having just the problems that I expected --
failures of the footswitch and the connectors which he used. He would
have been better off putting the switch which he made in series with the
*primary* of the transformer, not the secondary. I would have built the
footswitch box pretty much as he did -- but I would have run a power
cord directly into it, and put an AC outlet controlled by the switch in
the box. Then, it could be used to switch pretty much anything which
needed a footswitch, and the switch would not need to be a particularly
high-current one, either. *Certainly* -- don't use the phone plugs to
switch power line voltages.

Enjoy,
DoN.
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--- Black Holes are where God is dividing by zero ---

A soldering gun make a great degausing device for your TV or monitor with
pink or purple corners. Power on from 5' away, move the gun (sideways) in a
circular motion up to the screen, do several circular sweeps of the screen
and slowly pull back 5' before powering off. At this point, beware of the
TIP. Works well, though.
Respectfully,
Ron Moore

"Jeff Wisnia" wrote in message
...

My rapidly disappearing short term memory may be causing me repeat this
here, but a soldering gun also makes an ersatz demagnetizer for stuff
small enough to fit inside the loop formed by the tip, like say a
screwdriver. Just remember to move the steel part away before releasing
the trigger.

My rapidly disappearing short term memory may be causing me repeat this
here, but a soldering gun also makes .... Aw, ****e!

Happy New Year!

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

Don,

quote
I would have built the
footswitch box pretty much as he did -- but I would have run a power
cord directly into it, and put an AC outlet controlled by the switch in

the box. Then, it could be used to switch pretty much anything which
needed a footswitch, and the switch would not need to be a particularly

high-current one, either. *Certainly* -- don't use the phone plugs to
switch power line voltages.
unquote

This is almost scary. I was actually thinking of building my setup like
this. In fact, my footswitch is already wired like this. It basically
is a sewing machine switch. I'm still thinking about the microwave
transformer yet. I work at a maintenance facility and we have an
electronics section. I am going to talk to those guys next week and see
if any of them are comfortable pulling the transformer out of a
microwave and making sure the thing is DEAD and then I'll worry about
rewinding the thing.

Mike

According to mj :
Don,

I would have built the
footswitch box pretty much as he did -- but I would have run a power
cord directly into it, and put an AC outlet controlled by the switch in
the box. Then, it could be used to switch pretty much anything which
needed a footswitch, and the switch would not need to be a particularly
high-current one, either. *Certainly* -- don't use the phone plugs to
switch power line voltages.


This is almost scary. I was actually thinking of building my setup like
this. In fact, my footswitch is already wired like this. It basically
is a sewing machine switch.

Hmm ... I suspect that sewing machine switches vary. Mine, one
for a very old Singer 221B, is more than a switch. It is a stack of
carbon resistance elements, so you can control the speed with your foot
pressure.

If it is nothing but a switch -- wire it in series with the
primary of the transformer.

I'm still thinking about the microwave
transformer yet. I work at a maintenance facility and we have an
electronics section. I am going to talk to those guys next week and see
if any of them are comfortable pulling the transformer out of a
microwave and making sure the thing is DEAD and then I'll worry about
rewinding the thing.

The transformer, standing alone, with no power connected to it
is not dangerous. It is only when power is fed into the primary and the
original secondary is still present that it requires serious caution.

Note that the capacitor after the rectifier is a different
matter, as it can store high voltage charge for quite a while. But I
would expect a bleeder resistor to be a part of the construction, so
after a minute or so with no power it would be safe.

Good Luck,
DoN.

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I've measured the current with metering - just over 100 amps with a tip.
Tricky measuring either voltage or current due to the magnitude of values
and the way the tip changes resistance with heat.

Martin
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder



Joseph Gwinn wrote:
In article ,
Don Foreman wrote:


On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore"
wrote:


I was thinking of the welder mech that is used to link batteries into packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger.

Right, it's the resistance soldering device, soldering guns and
otherwise. The Wassco I mentioned is also AC. Capacitive discharge
DC works great for spotwelding batteries.

Gunner has mentioned soldering heavy wires by pressing a 250-watt gun
(sans tip) up against the splice and pulling the trigger, using the
current to heat the wires. I've never tried that, but it sounds
neat. The tip on a 250 watt gun is a few inches of about 1/8"
square copper and it get real hot right quick.


I recently measured the voltage across the tip of my 250-watt Wen
soldering gun - it's 0.175 volts rms or so (starts lower, then rises as
the copper tip heats and increases in resistance). To achieve the
stated 250 watts, the current will be 250/0.175= 1,429 amps. This could
almost be used for spot welding (where 4,000 amps is more common), and
the resulting magnetic field can pick up small pieces of iron (~50
grams).

For the record, the Wen Soldering Gun (Model 250, bought in 1963)
consists of a big AC power transformer with a one-turn secondary made of
3/8 inch brass rod. The open-circuit voltage (with tip removed) is
0.275 volts rms, for 118.9 volts rms in, so the transformer winding
ratio is 435:1. The gun was manufactured under US patents 2,701,835 and
2,680,187. Go to http://www.pat2pdf.org/ to get copies.

The Weller soldering gun is almost identical, although the tip of the
Wen is instead made of 0.164" diameter (~AWG #6) plated round copper
wire.

Joe Gwinn

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In article ,
"Martin H. Eastburn" wrote:

I've measured the current with metering - just over 100 amps with a tip.
Tricky measuring either voltage or current due to the magnitude of values
and the way the tip changes resistance with heat.

How did you measure the current? This is a very low resistance circuit,
so no standard inline ammeter is going to work without significantly
increasing the loop resistance, and thus decreasing the current.

One way is to measure both the open circuit voltage and the line voltage
- their ratio is the the same as the transformer turns ratio. As
discussed below, for the Wen 250 this ratio is 435:1.

Then measure the current in the 120-volt supply circuit, and multiply by
the turns ratio.

I did this with my Wen 250. It draws 2.2 amps (with a cold tip), so the
tip current is (2.2)(435)= 957 amps.

This is a little low for the 0.175 volts, as this would imply
(0.175)(957)= 167 watts, yet (120)(2.2)= 264 watts. One would expect at
least 90% efficiency in such a transformer, which did not get hot, so
the 167 watts cannot be correct.

Some better measurements are in order. I believe the 264 watts because
that measurement is direct, and exceeds the manufacturer's claim of 250
watts.

The best approach should be to measure the voltage across the tip at the
same time as the 120-volt current is measured.

Joe Gwinn


Martin
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder



Joseph Gwinn wrote:
In article ,
Don Foreman wrote:


On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore"
wrote:


I was thinking of the welder mech that is used to link batteries into
packs.
Don't know why I was thinking that. I'm sorry, I not sure what you were
referring to that is not DC output, unless it is the resistance welder and
not the charger.

Right, it's the resistance soldering device, soldering guns and
otherwise. The Wassco I mentioned is also AC. Capacitive discharge
DC works great for spotwelding batteries.

Gunner has mentioned soldering heavy wires by pressing a 250-watt gun
(sans tip) up against the splice and pulling the trigger, using the
current to heat the wires. I've never tried that, but it sounds
neat. The tip on a 250 watt gun is a few inches of about 1/8"
square copper and it get real hot right quick.


I recently measured the voltage across the tip of my 250-watt Wen
soldering gun - it's 0.175 volts rms or so (starts lower, then rises as
the copper tip heats and increases in resistance). To achieve the
stated 250 watts, the current will be 250/0.175= 1,429 amps. This could
almost be used for spot welding (where 4,000 amps is more common), and
the resulting magnetic field can pick up small pieces of iron (~50
grams).

For the record, the Wen Soldering Gun (Model 250, bought in 1963)
consists of a big AC power transformer with a one-turn secondary made of
3/8 inch brass rod. The open-circuit voltage (with tip removed) is
0.275 volts rms, for 118.9 volts rms in, so the transformer winding
ratio is 435:1. The gun was manufactured under US patents 2,701,835 and
2,680,187. Go to http://www.pat2pdf.org/ to get copies.

The Weller soldering gun is almost identical, although the tip of the
Wen is instead made of 0.164" diameter (~AWG #6) plated round copper
wire.

Joe Gwinn

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