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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 |
#12
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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. ![]() 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 |
#13
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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 |
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