Build your own CD battery tab welder for about $100.00+-

I have tested DOZENS of different car audio caps. The ONLY ones that met their rated specs are the 1F caps from Rockford Fosgate, Monster Cable, and Scosche. And ONLY their 1F caps. ALL the others that I tested were bogus. Many as low as 1/20th of their rated capacitance. BEWARE!

See: http://endless-sphere.com/forums/viewtopic.php?f=2&t=2633&start=810#p494786 for some of the testing results.
 
texaspyro said:
I have tested DOZENS of different car audio caps. The ONLY ones that met their rated specs are the 1F caps from Rockford Fosgate, Monster Cable, and Scosche. And ONLY their 1F caps. ALL the others that I tested were bogus. Many as low as 1/20th of their rated capacitance. BEWARE!

See: http://endless-sphere.com/forums/viewtopic.php?f=2&t=2633&start=810#p494786 for some of the testing results.
Click to expand...
Thanks, so will 3 x 1 farad caps be good ?
 
Joat, 3 REAL farad is enough (you might be able to get away with 2F), assuming you're operating on the 12v-17v adjustable range. That info is definitively all over this thread.

Texaspyro is stressing that you make sure your caps are ACTUALLY 1F, because most car audio caps and many other caps in general are poorly rated.
 
JOAT"Thanks said:
If you can't weld it with 3F, you need to be using a different type of welder. Otherwise you are just going to be blowing holes in the material or not making a good weld.
Click to expand...
 
Hey, Texaspyro, since you might be around here, I thought I should ask a question that might have a simple answer before I go ahead and waste time/money.

In the 40 or so pages I've read of this thread, I didn't see anyone using graphite as a electrode. I thought it might be viable for me to simply take a 1/2" or slightly smaller copper tube, cut it into a graphite block so that I have overlap surface on the interior diameter for snug conductance between the graphite and the copper. And, just a small 1/2" nub of graphite as the tip. Hope hope is that this would very rarely need sharpening because the heat tolerance of the graphite >> metals, while the graphite is still conductive enough that I wouldn't lose all of my energy.

Yet, no one on the thread seemed to do that....so would is simply be more resistance than I hope? I may have seen something about someone buying copper electrodes specifically designed with small graphite tips, but I forget where.
 
I purchased the CA2011XB capacitor and it only slightly welds. I do not recommend it. The clear giveaway that it's a fake is the fact that it's advertised in the title as 4F, but then in the fine print it says 2,000,000uF.

CAR 4-FARAD DIGITAL VOLTAGE METER CAPACITOR +2YR WARNTY NEW 4 FARAD CAP CA2011XB
http://www.ebay.com/itm/CAR-4-FARAD-DIGITAL-VOLTAGE-METER-CAPACITOR-2YR-WARNTY-NEW-4-FARAD-CAP-CA2011XB-/110864413296?pt=LH_DefaultDomain_0&hash=item19d008b270

I measured a DC capacitance of around 0.1F.

For suggested capacitors look here:

http://endless-sphere.com/forums/viewtopic.php?f=2&t=2633&start=810#p494786
 
Kin said:
I didn't see anyone using graphite as a electrode.
Click to expand...

I've used graphite electrodes for doing thermocouples. They don't contaminate the weld with foreign metals and don't need all that much current... graphite does not conduct all that well.
 
I guess i underestimate how poorly graphite conducts, I thought it might be decent.. I am thinking a graphite rod, with a copper cylinder fitting very tightly over the graphite rod until 1cm from the end, where there is a 1cm tall, 8mm diameter pointed cone. Would that 1cm cone be introducing too much resistance and thereby limiting the current? I apologize, I suppose this could could be calculated but I don't quite know the values and figure you might have an intuitive response.
 
texaspyro said:
Kin said:
I didn't see anyone using graphite as a electrode.
Click to expand...

I've used graphite electrodes for doing thermocouples. They don't contaminate the weld with foreign metals and don't need all that much current... graphite does not conduct all that well.
Click to expand...

what was your source for the graphite? any pictures or suggestions for electrode construction?

do you prefer the graphite or elkonite?

rick
 
rkosiorek said:
what was your source for the graphite? any pictures or suggestions for electrode construction?
Click to expand...

The bottom electrode is a graphite block from:
http://catalog.dcccorporation.com/viewitems/welder-accessories-2/welder-accessories?&bc=100|1019

A friend of mine machined the rod electrode/holder for me out of some funky reactor grade graphite. You might be able to use an electrode from a dry cell battery or an arc light electrode.

Be aware that graphite can conduct heat/electrons differenly along and across the grain.
 
ok...just bought the pyramid power supply. im hoping i can get some assistance in the build of this puppy. read 6 pages of this thread and will finish all the pages before i attempt the build. im going to make very detail pics, instructions and youtube videos in order to make sure im assembling this properly and make it easy for others to follow and to build their own. i have between 10-15 power packs for tools that have gone bad and want to bring some of them back to life and to also help out some friends with their battery packs.

Alex
 
found this scr thyristor on ebay...will it work in this application or is it overkill? the price is right...around $50 bucks with delivery or since its used am i risking getting a bad product?

http://www.ebay.com/itm/EUPEC-thyri...&otn=5&po=LVI&ps=63&clkid=8405388627237851564

!CCNItr!BGk~$(KGrHqZ,!iIE0GYjm3DGBNKcJ-FWK!~~_12.JPG
 
Hi Texaspyro, hoping that you monitor this thread and that it's better to ask the question in public:,

I just started working on some arduino projects, which are very simple to use, cheap, microprocessor boards with a C based, but somewhat simplified, environment. I was thinking it would be relatively easy for me to build a program that turned on a number of transistors with a certain length of pulse.

I don't have much experience with fets, and I don't know if it'll be enough to simply apply the voltage to their gates for X milliseconds, then turn off. But if that is enough, and if it's reasonable to turn on a bunch of mosfets with a few different pins simultaneously, then I could think about making something slightly more useful than just a thyristor switch.

And, if you think this might be something that could work, how would I go about learning about what sort of pulses might help me? I now that you want a micro pulse to burn off the oils before a more serious pulse, but I don't know much else. I'm also looking at contenders for the fet, and found a bunch of creatures that are rated for 100-300A and not too expensive, but I'd look more thoroughly to compare the resistances etc of everything.

So, because I realize I am just getting into this, I'm mostly looking into whether this would even be possible to do. I'm also wondering if there's much sense in it, obviously your setup is much more sophisticated and the code is more complicated, but I'm curious as to how much I might be able to benefit by using a $20 microprocessor board and $20 of FETs. Probably, I'm just going to gain some resistance in the whole situation >.<.
 
Alan B said:
Arduino (AVR) pins don't have enough drive for these short pulses, a driver is needed between the micro and the FET gates.
Click to expand...

I was thinking of using a smaller transistor to activate the mosfets either in pairs or otherwise (sets of some sort, or I guess I could activate them all at once), though I'm not sure how effective the timescales are, because I don't know much. Maybe it's just not worth it, given that I don't know enough about hardware in such precise time measurements. When you say Arduino pins don't have enough drive for these short pules- what do you mean? I know the pins are capable of turning on and off certain mosfets in other situations, so I assume it has something to do with the scale and speed.
 
http://endless-sphere.com/forums/viewtopic.php?f=2&t=2633&start=840

Arduino is fine using DelayMicroseconds instead of just delay. I have some code somewhere if ou want to see my example. I had it working for 5 welds but I think I damaged my arduino or fet driver... Something wrong with my circuit...
 
I'd start by reading: http://www.turtlesarehere.com/html/cd_welder.html

Then I'd take some drugs and go back to bed...
 
Thanks everyone. I only got through page 50 or so, so I missed some of those great links on page 57.

Texaspyro, the link you gave me was dead, but it just started working again. So, ehm, it's not dead.

Again, thanks for the information, this all is great.
 
hello guys
Is anybody knows what do you think about ultra capacitors ( maxwell and others) for cd welder application or for high pulse discharge machining? How compare these caps to the audio caps???
and why???
Thanks to the fantastics men.... :D
 
Ultracaps have much higher ESR than good audio caps. I max some Maxwell 58F, 15V caps. They have a 12 milliohm ESR and can only deliver 1000 amps. If you want to make long, relatively low current pulses they could work.
 
yes, ok...but what' s the trouble when you increase the capacitance of the circuit?, because I see few ultra capacitors which have very very low ESR ( bcap1200p270T05=0,56 mohm!!!) much better than audio car caps . I remember the threaads p 32 of this forum ( thanks to cesare250495 and Jeremy Harris) and the texaspyro comments... If amperage is pregnant, is it possible welding with a very low voltage (i.e 2.7V/0.001=2700A)????...just a question of simple man...
Thanks for answer...
 
I've followed this thread (and a few others), so I think I'm ready to make a cheap-as* welder. Looks like about $200 and not $100, but whatever. I've been following this thread for many rereads. As an aside, I've been an embedded systems engineer for well over a decade. Not quite as cool as texaspyro's intro, but I think it works. I do know how to handle mosfets and the like, but that might happen later. I've tried to keep everything as simple as possible. Seems to work, but I know I couldn't do a any sort of tig style welding with my power input.

I have only one question for texaspyro: what are you using for vent sensing?

Anyway the whole she-bang is cheap: about 40 usd if anyone is interested. That is just for a charge controller, but I did find a cheap power supply at 19 usd for 100 watts. Not the quickest, but it's cheap. Also, I will have a few SCRs that are well suited to this torture. Those can be had for 75 usd. All prices do not include shipping, but they do include testing. And testing as a set if one buys it that way. :)

I've found that the following ebay searches work very well for the caps you'll need: (don't bother with anything else)

monster cable cap
rockford rfc1
rockford punch cap
scosche ecap1

I've gotten an older rockford punch cap that does not have the bar code on the bottom. It only measures about 0.7 farads. Seems solid enough otherwise. It has a very simple white label.

~Z
 
mortain said:
yes, ok...but what' s the trouble when you increase the capacitance of the circuit?, because I see few ultra capacitors which have very very low ESR ( bcap1200p270T05=0,56 mohm!!!) much better than audio car caps . I remember the threaads p 32 of this forum ( thanks to cesare250495 and Jeremy Harris) and the texaspyro comments... If amperage is pregnant, is it possible welding with a very low voltage
Click to expand...

The main tricky bit with low voltage is the severely decreased welding current. It might not be enough to generate a large enough current to melt your metals.

As for an 'ultra' cap having a low ESR, can you give us a link? We can use that. :eek:

~Z
 
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