FOLLOW-UP...

The "Explanation" text I refer to below says that you put current THROUGH
the joint you are soldering. This can be done, but be careful. He expains
the effects of resistance in the joint.

Remember in ALL soldering, the goal is to heat the _JOINT_ and let it melt
the solder. [[but it is _very_ helpful to use a small blob of molten solder
to get a good heat transfer to the 'work".

The idea is to get in and get out without heating surrounding stuff any more
than necessary (including the solderer tips themselves)

Arcing is caused by INDUCTANCE. As Newton once said, "Inductanace abhores a
current change." [[much like Voltare once said: "Capacitance abhores a
voltage change.]]

When current flows in an inductance, the inductance will do "whatever it
takes" with the voltage across the inductor to keep the current constant --
including generating a *VERY* LARGE voltage in order to create a low
resistance arc (so to speak), when we foolishly try to interrupt the
circuit. This is how engine spark coils woik)


--
Steve N, K,9;d, c. i My email has no u's.


"Steve Nosko" wrote in message
...

"clifto" wrote in message
...
bill wrote:
... making your own soldering iron by
using the carbon rod from a C cell battery
(carbon zinc cell)
http://www.coldheat.com/
They have a three-minute QVC commercial for it.

Good info Clif...Bill, whatever,
Boy, you new guys sure don't know what's been around for a long
time...(:-)
OLD idea. LOW voltage, HIGH current.

It is called "resistance soldering". I believe it is most important
to
know that the current is only passed through ONE of the pieces being
soldered, not through the joint being soldered. In the QVC video, notice
that he only does one piece of wire and what look like solder blobs on a
board....

In fact, this is how soldering *GUNS* work! The gun "TIP" is a 'wire'
&
has a high current from a transformer secondary that is in the gun body.
Long ago I stopped buying soldering gun tips and just use #12 or #14 solid
copper wire. Sometimes in really weird shapes to unsolder IC and the
like.
It is interesting to see what the strong magnetic field around the tip
does
to molten solder... Reminds me of that recent NASA video about the solder
flux in space...
The (soldering gun) secondary is 1 or 2 turns for fractions of a volt at
MANY amps. I should measure it, but I think it CAN NOT damage a
transistor
since it is less than 0.4 volts (I think, far less)
I have a professional resistance soldering unit used for making dental
braces and similar things and it is powerful enough to do PL259s _VERY_
well. Heavy wire to the probe and large clamp and several secondary taps.
Interesting thing is that the manufacturer uses the blue handles from
Weller, so it looks like a Weller soldering iron, but with an extreemly
worn
and oxidized tip, since it is not tinned. Looks carbon-like.

More info I found with a quick Google:

Didn't read it all, but an explanation:
http://www.geocities.com/budb3/arts/meth/sldrrst.html

Build your own:
http://www.trainweb.org/bristol-s-ga...jects/rsu.html


The web had anything!


http://www.wassco.com/regressolhan.html

http://www.contacteast.com/product/g...p?parent_id=16
http://www.greenspun.com/bboard/q-an...?msg_id=004VTC
Build your own (model railroad magazine references)


http://index.mrmag.com/tm.exe?opt=S&...put=3 &sort=d


http://www.ares-server.com/Ares/Ares...partment&ID=81
Beware URL WRAP






It's obvious that it's
running current through the object to be soldered; they show the little
red "power" light going on and off as they touch and un-touch a solder
pad on a circuit board.

Like the Radio Shack butane unit, the device is $20 and tips are $10.
They have three different tips shown. Takes 4 AA batteries.

"This tool is appropriate for most electrical projects with wires
between
18-24 gauge, small jewelry repair, and electronic projects."

"We do not recommend it for soldering of large metallic components that
require a lot of heat transfer, such as heavy gauge wire. Also be aware
that high temperatures will be created during active soldering; please
consult your component's datasheet for any special precautions needed."

"What is the spark I see sometimes during soldering?
"The spark (arc) is caused [sic] electrical current passes from one half
of the tip to the other. Although the tool's spark should not damage
any electrical or electronic components, we recommend caution when
soldering sensitive components. Also, ensure that the tool is not used
in flammable or explosive environments, such such as near gas or
gasoline fumes."

One thought that occurs to me is that it looks like a DYNAMITE tool for
desoldering with a suction device, since it appears that solder doesn't
stick to the tip it ships with. Can't speak for the other tips; they
look more metallic and are not demonstrated on the site. They recommend
wick for desoldering, but those of us not of that religion might have
an alternative.

--
"Kerry arrived in-country with a strong anti-Vietnam War bias and a
self-serving
determination to build a foundation for his political future."
-- Rear Admiral Roy Hoffmann, USN (Ret.), May 4, 2004

Steve Nosko wrote:
"clifto" wrote...
http://www.coldheat.com/

Good info Clif...Bill, whatever,
Boy, you new guys sure don't know what's been around for a long
time...(:-)
OLD idea. LOW voltage, HIGH current.

It is called "resistance soldering".

I knew that. Seriously, to me the big celebration here is the material
that allows you to make a low-resistance connection to the work every
time.

We used to have fun with a low-voltage, high-current power supply that
some wag labeled "Zotz I" (but everyone mistook the markings and called
it "zotsy"). It was the (fairly) early days of tantalum caps, and we'd
hang Zotzi across the power supply rails to find shorts by heat. On
occasion we'd launch a smelly and formerly shorted tantalum that way.

--
"Kerry arrived [in Viet Nam] with a strong anti-Vietnam War bias and a self-
serving determination to build a foundation for his political future."
-- Rear Admiral Roy Hoffmann, USN (Ret.), May 4, 2004

Bill Turner wrote:

On Fri, 20 Aug 2004 13:58:15 -0500, "Steve Nosko"
wrote:


Arcing is caused by INDUCTANCE.


__________________________________________________ _______

The kind of arcing we're talking about is caused by heating at the point
of contact which is sufficient to vaporize a small amount of the
conductor. If significant inductance is present, the current and
therefore the heating can be magnified.

--
Bill, W6WRT
QSLs via LoTW

Inductance doesn't magnify current. In fact, it's a fundamental property
-- even a definition -- of inductance that it resists any change in
current. And to do that, it can elevate the voltage by a whole lot. For
example, if you have current flowing through a coil and break the
connection, you commonly see a spark or arc (and can get a shock even
with a low applied DC voltage). This is caused by the very large voltage
the inductor produces in its effort to keep the current flowing through
what has become an open circuit.

Roy Lewallen, W7EL