Resistance-No Resistance wire welder

[TomCatt]

Finally stopped at Walgreens and CVS today, no freebies for me; picked up a two pack at Walgreens.

I have a LM2577 laying around here somewhere, ordered some 1000uf/50V caps from eBay last night. So I may try doing one from 'scratch' when the caps come in.

Meanwhile I'll try out the camera welder


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[jmarkus]

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Schematic with digikey part numbers. To that BOM you also need the LM2577 board, some alligator clips, some wire and solder and a box. The digikey list is about $7, the LM2577 another $7 and then the other misc supplies is going to bring it to around $25 with shipping.

30g silver to 32g or 34g kanthal was a piece of cake at 35v. I am building this at work so that's all the wires I have here, I will try the 28g kanthal when I get home.

Also, I tested the current draw on the battery and it is about .2A

You can see the trim pot for voltage adjustments in pic 3. I used some loctite to secure the board to the side of the box, everything else is hot glue.

awesome, another brilliant build! welding being a snap with silver sounds too good to be true...do you even have to mess around cleaning wires and making short runs and all the other nuances?

 

[comptechltd]

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Schematic with digikey part numbers. To that BOM you also need the LM2577 board, some alligator clips, some wire and solder and a box. The digikey list is about $7, the LM2577 another $7 and then the other misc supplies is going to bring it to around $25 with shipping.

30g silver to 32g or 34g kanthal was a piece of cake at 35v. I am building this at work so that's all the wires I have here, I will try the 28g kanthal when I get home.

Also, I tested the current draw on the battery and it is about .2A

You can see the trim pot for voltage adjustments in pic 3. I used some loctite to secure the board to the side of the box, everything else is hot glue.

Not having a LM2577 in front of me nor me being an electrical engineer, I noticed the LM2577 is grounded in 2 places. Where on the board did you connect these and I assume they ground back to the battery??

Steve

 

[TomCatt]

The LM2577 comes in a module from eBay - simple +/- in and +/- out connections; a pot is included on the module.


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[comptechltd]

Sorry for being such a noob. I understand that its a module. In his drawing he shows 2 grounds attached to it. Are these internal?

Steve

 

[BJ43]

Sorry for being such a noob. I understand that its a module. In his drawing he shows 2 grounds attached to it. Are these internal?

Steve

The neg in goes to the battery neg and the neg out goes to the neg side of the cap.... I think

 

[jmarkus]

just ordered the parts needed for the step-up welder, wondering if a protected 14500 would also work?

 

[comptechltd]

The neg in goes to the battery neg and the neg out goes to the neg side of the cap.... I think

I guess my question is 'are all the grounds hooked together'???? Again...I am just ever so slightly above a noob level here.

Steve

 

[TomCatt]

Batt neg to LM2577 input neg, LM2577 output neg to capacitor neg; so, yeah they are all connected. When you touch wires, you complete the circuit and discharge the capacitor.


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[dsy5]

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You can see the trim pot for voltage adjustments in pic 3. I used some loctite to secure the board to the side of the box, everything else is hot glue.

I asked before, but you might have missed it - what is the trim pot value?

 

[gsa]

just ordered the parts needed for the step-up welder, wondering if a protected 14500 would also work?

any 3.7v battery will work. For that matter, any power source 3.5-40v will work, an extra 12v power supply, an old ego, 9volt battery, 5v charger etc. The current draw is 200ma but I would supply 500ma just to make sure you don't hit any internal protection on your power supply.

 

[gsa]

I guess my question is 'are all the grounds hooked together'???? Again...I am just ever so slightly above a noob level here.

Steve

It is a common ground, so yeah you could connect all the grounds together but it makes most sense to put battery ground to lm2577 -in and then on the lm2577 -out tie everything together at the capacitor neg lead, that is what I did. Tomcat may have explained it better

 

[breaktru]

Finally stopped at Walgreens and CVS today, no freebies for me; picked up a two pack at Walgreens.

I have a LM2577 laying around here somewhere, ordered some 1000uf/50V caps from eBay last night. So I may try doing one from 'scratch' when the caps come in.

Meanwhile I'll try out the camera welder

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I'm not abandoning my Flash Welder. It works too good. And cheap too.

Hey: I found NEW flash boards for a buck and Photo-Flash Capacitors for a buck too. See the usual place for details.

 

[gsa]

I asked before, but you might have missed it - what is the trim pot value?

Not exactly sure, or why it is important unless you are building your own lm2577 board? The board I used has a max output of 35v so I just cranked it up all the way. To back it down, just put the dmm leads on the welding clips and turn the pot.

The ebay link actually has the spec sheet listed for the pot though, here it is if you need it: http://www.bourns.com/PDFs/3296.pdf

 

[gsa]

awesome, another brilliant build! welding being a snap with silver sounds too good to be true...do you even have to mess around cleaning wires and making short runs and all the other nuances?

I didn't clean anything, making sure you have a solid connection and a short piece of wire on the kanthal is still important though, otherwise you just add resistance to the arc.

To be honest, I am not sure why the lower voltage, higher uf cap works so much better but it does. Maybe the cap discharges a little slower vs the photo cap, giving it a little more time to weld? Either way, this is pretty much exactly what is inside the $100 unit and after seeing the difference between the two, I can understand why he made this engineering decision.

Will test the 28g kanthal after I get kids to bed.....

 

[gsa]

I'm not abandoning my Flash Welder. It works too good. And cheap too.

Hey: I found NEW flash boards for a buck and Photo-Flash Capacitors for a buck too. See the usual place for details.

I thought you had a 40v step module ordered from PRC?

 

[dsy5]

Not exactly sure, or why it is important unless you are building your own lm2577 board? The board I used has a max output of 35v so I just cranked it up all the way. To back it down, just put the dmm leads on the welding clips and turn the pot.

The ebay link actually has the spec sheet listed for the pot though, here it is if you need it: http://www.bourns.com/PDFs/3296.pdf

I'm not planning on building a board, I am going to remove the pot and put a selector switch that ties different resistance values into the board so that I can select different voltages without needing to turn a pot or use a DMM.

It will be similar in nature to the DIP switches on the original Greek unit.

That link for the pot doesn't tell me anything - there should be a value stamped on the pot itself.

 

[Lentulusbatiatus]

I sweep up and make the drinks for people just above noob level Steve, can I fetch you anything ? lol

 

[comptechltd]

Thanks Mev ,

I think I'll just stand in the corner and watch the masters work. FWIW I have ordered most of the parts for gsa's design. Just gotta find the right size box and then we'll see if I can electrocute myself....lol

Steve

 

[JazzyTech]

Anything that gets people's minds working and interested in learning is a great thing! I spent many years repairing coin-op games and pinball machines with skills that came from my interest in electronics. It's been sad seeing "Radio Shack" become what it is today. Surface Mounted devices made it a lot harder to work in tiny spaces. Good for mp3 players; bad for hobbyists. This is one project that can show the basics of some electronic principles and be useful at the same time. win/win