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Resistance Soldering 2

By Ben Y. Wed, 17 Dec 1997

I just completed my home built resistance soldering rig, based on the plans and info provided by some members a few months ago. And it works great!!

I did deviate from the parts lists, though. I found that the Radio Shack transformer is no longer available. Besides, using only a 4 amp trans. bothered me. After some brief head-scratching, it dawned on me to use the guts from an automotive battery charger. Those things are available in all kinds of big amperage ratings.

The one I chose was a 6-12 volt 10 Amp manual model made by Exide. I bought mine from K-mart for $40. The bonus was that I now also had a fancy case, wiring, and a power cord. The only extras needed were a few stake-ons, a fuse holder, two binding posts, and a $5 lite dimmer (*).

Basically, I removed the existing circuit breaker, diodes and meter, installed the fuse holder in the line, installed the dimmer in the case where the meter used to be, and rewired the whole thing using most of the wires salvaged. I used the existing wires as much as possible since they were large enough to handle the amperage and already had connectors that matched the other components.

The tool was made according to the plans, from an old Radio Shack soldering pencil I had laying around. I did end up getting a box of carbon rods from a welding supply shop. I had to by a box of 50 for $18. This is enough for about 10 lifetimes, I think. At least I’ll have plenty of spare tips!

The other modification I made was to increase the output. The transformer is a center tapped type, which is like having two transformers side by side electrically. I cut the common lead, and rewired the now two secondary windings in parallel. This boosted the capacity to about 20 amps. I measured all the good stuff, and it turns out, it comes to about 150 watts. So for about $75, I have a $300 unit that, thanks to the original case, doesn’t even look home made!!

If anyone is interested in the specific details, please feel free to contact me. Even if you don’t know very much about electrical stuff, I can talk you through it.

And not to forget, my many thanks to those who provided bits of information!!

Ben Y.

[* Editor’s note: take care when testing out the dimmer, as most of them are not originally designed for using a transformer as a load…]

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