Resistance-No Resistance wire welder

[yo han]

Here's what I'm going to build.
First time I used a program to draw a circuit so please don't laugh
Any comments are welcome. Oh, and since my knowledge on electronics is very limited I have no idea what values to use for D1 and D2.
Any suggestions?
Anyway, what I would need is a switch which can switch the positive and ground from the capacitors to the terminals and by flicking it the other way it should switch the measuring wires of the resistance meter to the terminals. Do switches like that exist?

 

[awsum140]

That'll work, yo han! I just ordered a module like the LM2577 but that goes to 60 volts and some 1000mfd 250 volt electrolytics. I want to fool with higher voltage and lower capacitance to see if weld penetration is better that way. One of the problems I'm having is that the resistance wire breaks off jus beyond the weld from the extreme heating making it brittle. I want to see if I can mitigate that as it gets very frustrating when it breaks as you finish a coil!

 

[yo han]

Great, please keep us updated.
Any advce on the diodes and switch in my previous post?

 

[awsum140]

I'd say 1N4001 would work fine. Any normally open pushbutton switch will work as well. I got mine from Radio Shack in a bag of five for about two dollars.

 

[yo han]

Thanks, but I mean the switch for choosing between the welder and the resistance meter which I describe in the last part of that post.

 

[awsum140]

I still don't see the purpose. I use the ohm meter to measure from the negative post, zero resistance wire, after the first weld to determine how long the resistance wire should be. That needs a flexible lead, separate from the terminals for welding so it can be moved along the wire to the desired resistance reading. I use it again after I complete the second weld to verify the overall resistance of the welded wires. Have you got something else in mind?

 

[yo han]

My plan is as follows:
Uncut kanthal in the fixed terminal on the unit.
Nickel in the free terminal then weld.
Switch to resistance mode and, with the free terminal still attached, slightly open the fixed terminal and pull kanthal back until I reach desired resistance and then cut it there.
Switch to welding mode, put nickel in the fixed terminal and weld.

 

[Innocuous]

sounds productive ;-)

 

[awsum140]

In that case I think you'll need to make the fixed post positive. Then a single pole double throw switch could be used to switch between the capacitor and the ohm meter. You will also want to make sure you discharge the capacitors completely before switching modes. Any residual charge will mess with the reading and could blow out the ohm meter. If you used a double pole double throw switch, the second pole could be used to simultaneously switch the connection and provide a discharge short for the capacitors.

Personally, I'll stick to the flexible lead method, KISS principle.

 

[yo han]

I'm thinking about a 3-position switch in which the middle position will short the caps so I'm sure the're discharged before using the resistance meter. But like I said, I can reason logically but I've got no idea if something like that exists.

 

[awsum140]

A DPDT will do the same thing. On the side that connects the ohm meter to the post you also connect a bleed down circuit, 220 ohm resistor, but I'm still trying to figure out how you connect to the loose end of the coil, as it were, unless you clip it into the other welding post. Again, the risks are just too high, although a three pole double throw switch would work to disconnect the other post from the welding circuit completely. Either way, I still think a simple test lead system is safest and easiest.

 

[Mad Scientist]

sounds productive ;-)

Here's what I'm going to build.
First time I used a program to draw a circuit so please don't laugh
Any comments are welcome. Oh, and since my knowledge on electronics is very limited I have no idea what values to use for D1 and D2.
Any suggestions?
Anyway, what I would need is a switch which can switch the positive and ground from the capacitors to the terminals and by flicking it the other way it should switch the measuring wires of the resistance meter to the terminals. Do switches like that exist?

A simple solution is a double pole, double throw switch with break before make contacts. There is no need to bleed the capacitors. The center poles of the switch connect to your wire clips. Thrown one way the capacitor side is connected to the wire. Thrown the other way the meter is connected to the wire. No cross connections so no danger to the meter.

Here's one that will likely work fine.
Switch. It costs a little more than 3 bucks.

 

[yo han]

Thanks guys.
Yes, a DPDT On/Off/On switch should work.

but I'm still trying to figure out how you connect to the loose end of the coil, as it were, unless you clip it into the other welding post.

I don't think I understand what you mean.
There is no loose end during the process except at the end when welding the NR wire to the R/NR piece. The measuring has already been done at that momment.

 

[awsum140]

It's a result of two different methodologies for welding/measuring I guess. One of these days I'll do a video or maybe a series of photos showing my method. There are always lots of coils to replace, so it will happen one day.

I have come up with yet another modification to the welder itself. I'm putting in a DPDT switch to switch polarities of the welding posts. It's probably not needed, but what the heck. It does make a difference when welding, especially if the zero resistance wire is a substantially heavier gauge wire. I suspect that may be due to actual electron flow at the weld joint.

 

[yo han]

It's a result of two different methodologies for welding/measuring I guess. One of these days I'll do a video or maybe a series of photos showing my method.

Yeah, it's kinda difficult to explain in words.
I think this will be my final version for now...

 

[awsum140]

That'll work. Just make sure the voltmeter reads "0" before you check resistance.

 

[yo han]

It shouldn't be necessary but yeah, I'll probably do that anyway
Oh, and I want an eGo/510 connector on there as well. Can these things be bought separately or do I have to salvage one from an old battery?

 

[awsum140]

You can salvage one, I've done that for an 808 connector since I use 808 batteries and devices quite a bit, but I ordered some 510 battery connectors from MadVapes over here in the US. They can be a bear to solder to if they're not chromed brass though. The 808s I have are all chromed brass so it was easy to work with.

Prewired 510 Battery Connector, Sealed

If you're stuck for one, PM me.

 

[Mad Scientist]

It's a result of two different methodologies for welding/measuring I guess. One of these days I'll do a video or maybe a series of photos showing my method. There are always lots of coils to replace, so it will happen one day.

I have come up with yet another modification to the welder itself. I'm putting in a DPDT switch to switch polarities of the welding posts. It's probably not needed, but what the heck. It does make a difference when welding, especially if the zero resistance wire is a substantially heavier gauge wire. I suspect that may be due to actual electron flow at the weld joint.

Yes, the electron flow idea makes sense. It's actually the impact of electrons at the point when it arcs. Electrons flow from negative to positive. What reminded me was how a TIG welder works. The electrode is negative and electrons flow from the negative electrode to the positive work. The work gets much hotter than the electrode as the electrons bombard it. Same thing in an X-ray tube. Highly accelerated electrons bombard the anode and the anode gains much more heat than the cathode.

If that's what's happening, you should see better results if you connect the thicker wire to the positive side of the wire welder.

 

[Innocuous]

Thicker, or most conductive (iirc)