Resistance-No Resistance wire welder

Status
Not open for further replies.

bapgood

Vaping Master
ECF Veteran
Verified Member
Apr 16, 2012
4,426
6,599
45
Utah
Well guys I think you have done great job on this!!! :toast:

I am pretty pleased with both the camera and LM2577 units. I think it all comes down to your touch and ability to dial it in to you and your materials.

I just ordered the pcb's to build the 600w dual pulse CD welder. Its not practical for this alone (unless you want it to be) but I have plenty of other projects that I can use it for. But I will let you guys know how it works for this.

For you electrical guys....I did briefly talk to the designer of the CD welder about using mosfets for this applications and this is what he said.

"1: Your capacitors are very small and usually have an internal ESR(like a series resistor) If this ESR is too big it will slow the discharge of the capacitor. 2: A mosfet circuit needs 15 volt on its gate to let a negative current flow and up to 35v measured between gate and negative to make a positive current flow. 3: The mosfets has to be connected correctly for a positive or negative current to flow or they will get damaged.4; Your mosfet has to be rated with the correct "on resistance", if the on resistance is too high it will act as a too high ESR."

It sounds a little complicated but not impossible if the correct components were used.
 

UA72Riddle

Ultra Member
ECF Veteran
Verified Member
Dec 27, 2010
1,724
1,257
47
Griffin, GA
I'm not sure what I am doing wrong, but I have went through about 3 inches of wire trying to make it work again, with no success. I finally got fed up and tossed the camera in the trash. I will start again when I have a better camera.

Only the very end of the wire would fuse, but the wire fused perfectly where it was gripped by the clips....go figure.
 

bapgood

Vaping Master
ECF Veteran
Verified Member
Apr 16, 2012
4,426
6,599
45
Utah
I'm not sure what I am doing wrong, but I have went through about 3 inches of wire trying to make it work again, with no success. I finally got fed up and tossed the camera in the trash. I will start again when I have a better camera.

Only the very end of the wire would fuse, but the wire fused perfectly where it was gripped by the clips....go figure.

You might want to elaborate on your setup a little more. When using a camera you will actually want more than one camera, or more than the single capacitor.
 

Lentulusbatiatus

Senior Member
ECF Veteran
Sep 19, 2012
266
90
Wakefield
  • Deleted by classwife
  • Reason: Unregistered Supplier

mre777

Super Member
ECF Veteran
Verified Member
Nov 4, 2012
460
365
Daytona Beach
well I desoldered the trim pot off the LM2577 board and wired in a new 10k ohm linear quality pot. Now the board is doing all kinds of strange stuff, like going up to 50 volts, wont go lower then 15 volts, and when I go to charge up a 2000uF cap at 24 volts the output drops to nothing and I have to disconnect it from power for it to reset. The new pot is in right and there are no solder bridges (I have a bit of experience in doing this kind of thing) what I would like to know is if anyone has successfully swapped out the stock potentiometer for a remote one, and if so what type and where did they get it.
 

gsa

Senior Member
ECF Veteran
Verified Member
Oct 27, 2009
214
167
49
Well.......I got my welder built using gsa's guide and no go. I think the board is bad. I get zero volts at the posts. I've checked and double checked my connections. The adjustment screw just spins and spins. I'll try to tear it apart tomorrow and see what I may have done.

Steve

Make sure the battery is actually making contact in the holder. Mine needed a little tweaking of the springs to get it to make the connection.
 

gsa

Senior Member
ECF Veteran
Verified Member
Oct 27, 2009
214
167
49
GSA,

Upon troubleshooting my welder not working and checking and double checking my connections I found that I am NOT getting voltage out of the resistor. Got volts going in but nada coming out. Is it ok to remove it?? Not sure whats up.

Steve

That doesnt make sense. What does your meter say the resistance of the resistor is?
 

gsa

Senior Member
ECF Veteran
Verified Member
Oct 27, 2009
214
167
49
well I desoldered the trim pot off the LM2577 board and wired in a new 10k ohm linear quality pot. Now the board is doing all kinds of strange stuff, like going up to 50 volts, wont go lower then 15 volts, and when I go to charge up a 2000uF cap at 24 volts the output drops to nothing and I have to disconnect it from power for it to reset. The new pot is in right and there are no solder bridges (I have a bit of experience in doing this kind of thing) what I would like to know is if anyone has successfully swapped out the stock potentiometer for a remote one, and if so what type and where did they get it.

Was there something wrong with the stock pot?
 

mrelwood

Senior Member
ECF Veteran
Verified Member
Jan 25, 2012
267
192
Finland, Europe.
After hours and hours of reading related threads, ordering the components, trying to understand the LM2577 datasheet, and trying a few circuits, I realize that everybody is using a ready made LM2577 BOARD instead of just the LM2577 component. Doh! It seems the inductor is a crucial part for the board, and I have none at hand.

What do you guys think would be the smartest way to proceed? Buy the actual LM2577 board from eBay or find a suitable inductor and wire up a board of my own? I am pretty good with soldering and DIY, so I don't mind doing stuff. But I don't like the idea of it, or trying to fit parts of a disposable camera in the box I got for this.
 

mre777

Super Member
ECF Veteran
Verified Member
Nov 4, 2012
460
365
Daytona Beach
Was there something wrong with the stock pot?

No there was nothing wrong with it but I would like the adjustment to be easily accessible with a knob from the outside of the box. I was planing to make one that I could use as a little portable variable power supply for other projects that I play with.
 

gsa

Senior Member
ECF Veteran
Verified Member
Oct 27, 2009
214
167
49
No there was nothing wrong with it but I would like the adjustment to be easily accessible with a knob from the outside of the box. I was planing to make one that I could use as a little portable variable power supply for other projects that I play with.

Ah, cool. Maybe it would be easier to put a little holder on the box for a small screwdriver?
 

bapgood

Vaping Master
ECF Veteran
Verified Member
Apr 16, 2012
4,426
6,599
45
Utah
Now I just need to figure out a good way to attach it :D

ACFB9C8E-E0C6-463F-B540-F14603A84995-228-000002AF62771C58_zpsdbb90e09.jpg
 
Status
Not open for further replies.

Users who are viewing this thread