Re: Homemade Resistance Soldering Unit

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 <2nehr1t7f8gq4ndm32v86058h5p5gs7nfd@xxxxxxx>,
 Don Foreman <dforeman@xxxxxxxxxxxxxxxxxxxx> wrote:


On Sun, 1 Jan 2006 22:21:57 -0600, "Ron Moore" <mlogical@xxxxxxxxxxx>
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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