Resistance-No Resistance wire welder

[gdeal]

Ha it works! Cheap 7 buck disposable with flash just got it at the drugstore. Left the board in the case so I didn't shock myself (still did, watch the wire ends ) Hooked two jumpers to either side of the cap. you dont need to hole the button for more then .5 sec, any longer and it wont take a good hold or just melt the thin wire . Its took some practice but i got a good hold on a .005 Nichrome to 30g fine silver wire. didnt have much luck with the 30g Nichrome, might need to play with it more. This is so cool!

I think you may have just got the mod of the year award! Great job!

 

[gsa]

Awesome! Thats what I am talking about. A battery, a fuse, a cap and BAM!!!

Can you make out the uf or the voltage on the cap?

 

[mre777]

Awesome! Thats what I am talking about. A battery, a fuse, a cap and BAM!!!

Can you make out the uf or the voltage on the cap?

Nah the cap has no labeling except the number 643... Other disposable cams might have ones you can read I remember the last time I took one apart it did but that was a while ago. (used to use these flash circuits to zap my friends ) the nice thing is it runs on a AA battery and that comes with it. Im sure with some tinkering I could mount this in a little box and all but I really just wanted to try it out to see if it would work.

 

[TBinAZ]

Wow. It's a mini arc welder. Brilliant!

 

[gsa]

I suppose it could be 643uf. I think the cameras use high voltage discharge caps, thats why they make good "shockers".......

 

[mre777]

yeah I think they are rated for 500 or 1000 volts but the capacitance is not something special, its the really high speed switching booster that steps up the 1.5 volts threw that transformer. Thats why they have that whining sound when that are charging.

 

[TBinAZ]

Oh, dude, I'm so going to have to try this out. My eyes and shaky hands can't take dealing with crimps anymore. LOL. I always seem to pull apart the twists at the least opportune moments too. Nice.

 

[mre777]

It does seem to work better with nonresistance wires other then the fine silver stuff I have. Its kind of hard to get a good tack on the silver but I have some steel wire that works great. I did the steel to a 34g kanthal no problem. The videos look easy because his is regulated to what works best for the wire diameters he is using but with the camera flash you kinda have to get the feel for it and experiment to dial it in for a good connection. Plus I think looking at all these mini arcs is starting to affect my retinas

 

[gsa]

yeah I think they are rated for 500 or 1000 volts but the capacitance is not something special, its the really high speed switching booster that steps up the 1.5 volts threw that transformer. Thats why they have that whining sound when that are charging.

Here is a little more info on photoflash caps: Photoflash capacitor - Wikipedia, the free encyclopedia
looks like there may indeed be something special about them. I'm with you on the transformer though. Higher total voltage and less capacitance = nasty shock.

I'm really excited to see the camera flash working, just hoping that the lower voltage, higher discharge cap will be a little safer to use, plus it seems like all the CD welders are using this setup rather than the high voltage with transformer version. I really am not sure about this theory right now but the parts are ordered from digikey so I will report back in a couple days. I noticed my links were broken, so I will go back and fix that later.

 

[Lbox88]

Wish I had a full schematic, I probably have enough parts from EE school to make it without even leaving the house.

 

[breaktru]

Ha it works! Cheap 7 buck disposable with flash just got it at the drugstore. Left the board in the case so I didn't shock myself (still did, watch the wire ends ) Hooked two jumpers to either side of the cap. you don't need to hold the button for more then 0.5 sec, any longer and it wont make a good connection or just melt the thin wire . It took some practice but i got a good hold on a .005 Nichrome to 30g fine silver wire. didn't have much luck with the 30g Nichrome, might need to play with it more. This is so cool!

Very nice mre, good work.

Diver uses 25v to 40v to charge a 1000uF capacitor and a 10440 Li-Ion. He originally used a 2200uF cap. He doesn't say what DC-DC converter he's using but I saw a photo of another member's and it looks like this guy was using an ebay 30v max one shown HERE

 

[gsa]

Wish I had a full schematic, I probably have enough parts from EE school to make it without even leaving the house.

Only 2 days for the engineer to show up, not bad!



I wasn't sure where to put the switch, other choice was between the fuse and cap so the fuse and resistor would be isolated on the battery side.

 

[mre777]

Here is a little more info on photoflash caps: Photoflash capacitor - Wikipedia, the free encyclopedia
looks like there may indeed be something special about them. I'm with you on the transformer though. Higher total voltage and less capacitance = nasty shock.

I'm really excited to see the camera flash working, just hoping that the lower voltage, higher discharge cap will be a little safer to use, plus it seems like all the CD welders are using this setup rather than the high voltage with transformer version. I really am not sure about this theory right now but the parts are ordered from digikey so I will report back in a couple days. I noticed my links were broken, so I will go back and fix that later.

Well I hope yours works great, the flash has a bit of a learning curve to it and is not for everyone. Nice link by the way. If you get yours working Ill build one too and turn this flash into a rail gun

 

[TomCatt]

Tentative parts list:

Battery- 3.7v AW IMR 18650 from my stash $0
Batter holder- Digi-Key Part Search $2.83
Resistor- 10w 3.6ohm SQP10AJB-3R6 Yageo | 3.6W-10-ND | DigiKey $0.63
Capacitor- 1.5F 5.5v "supercap" Digi-Key Part Search $4.19
On/Off Switch- Not really needed IMO. I will just take my battery out when not in use.
Momentary Switch- SPST NO 2A Digi-Key Part Search
Alligator Clips- Plenty of those in the junk drawer, might get some nice ones if this works though. $0
Fuse: 2A 125vdc Digi-Key Part Search $1.95/qty 3
Wire, solder etc- again from the junk drawer. $0

So less than $11 before shipping for bare bones parts to give it a try. I think I will.

I calculated the capacitor charge using this calc here: Charging a Capacitor

So at 3.7v-4.2v power with the 3.6ohm resistor and a 1.5f cap = about 5 seconds to charge to 600000uf which ought to be enough to weld the wire, if not holding the button longer will increase the charge but adding more caps may be a better solution. The resistor should limit the battery discharge to around 1 amp and the 2 amp fuse as a safety, well within the limit for the battery. 10 watts should be way more than enough for the resistor as well.

Am I missing anything here?

Ha it works! Cheap 7 buck disposable with flash just got it at the drugstore. Left the board in the case so I didn't shock myself (still did, watch the wire ends ) Hooked two jumpers to either side of the cap. you don't need to hold the button for more then 0.5 sec, any longer and it wont make a good connection or just melt the thin wire . It took some practice but i got a good hold on a .005 Nichrome to 30g fine silver wire. didn't have much luck with the 30g Nichrome, might need to play with it more. This is so cool! View attachment 167395View attachment 167396View attachment 167397View attachment 167398

Awesome!

Thanks, I am outta my league here on the technical aspect of pulling this together..so I just gonna I would definitely get one of these if it was available and cheap, just for the entertainment factor alone.

You and me both, g

 

[gsa]

Very nice mre, good work.

Diver uses 25v to 40v to charge a 1000uF capacitor and a 10440 Li-Ion. He originally used a 2200uF cap. He doesn't say what DC-DC converter he's using but I saw a photo of another member's and it looks like this guy was using an ebay 30v max one shown HERE

Good stuff right there. From those pics it looks like this is the one he is using: http://www.ebay.com/itm/DC-DC-4A-4-5-32V-to-5-42V-12V-24V-step-up-BOOST-converter-power-module-/130770051722?pt=LH_DefaultDomain_0&hash=item1e7280a28a only thing that doesn't add up is 4.5v input on the board and supplying 3.7v with the battery but it is probably close enough. Everything else looks identical with the exception that the ebay listing uses a trimmer pot instead of dip switch, but that could easily have been desoldered and replaced.

Looks like the welding cap is 1000uf 50v.

 

[breaktru]

Good stuff right there. From those pics it looks like this is the one he is using: http://www.ebay.com/itm/DC-DC-4A-4-5-32V-to-5-42V-12V-24V-step-up-BOOST-converter-power-module-/130770051722?pt=LH_DefaultDomain_0&hash=item1e7280a28a only thing that doesn't add up is 4.5v input on the board and supplying 3.7v with the battery but it is probably close enough. Everything else looks identical with the exception that the ebay listing uses a trimmer pot instead of dip switch, but that could easily have been desoldered and replaced.

Looks like the welding cap is 1000uf 50v.

The photo I linked to was by another member on the Greek forum who made one also. He used that DC-DC step-up but if you look closely, he used TWO batteries. Still don't know what Diver used.

I think @mre777 has a better/cheaper idea with the flash/strobe from a 7 buck camera. As long as the arc can be controlled for different gauge wire w/o melting it.

If you can remove the strobe circuit/board, you can make a nice box for it.

http://www.instructables.com/files/deriv/.../071X/FHEZC8IR/FML071XFHEZC8IR.MEDIUM.jpg

 

[gsa]

1000uf 50v cap ECA-1HM102 Panasonic Electronic Components | P5186-ND | DigiKey
Adjustable boost converter in 3-34v out 3-35v Amazon.com: LM2577 DC-DC Adjustable Step-up Power Converter Module: Car Electronics

The trim pot on that should make dialing it in a little easier.

Edit. Bought those items too

 

[gsa]

Found this handy little calculator for estimating the total energy stored in the cap: Energy Stored on a Capacitor

So using the known values of from the photos breaktru linked to, we have 30v charge on a 1000uf cap = .445 joules

Lets say the cap is going to discharge fully in 10 milliseconds. Using this calculator Joules to watts (W) conversion calculator we get about 50 watts.

Using the same calculators and plugging in the numbers for the not voltage boosted circuit (1.5f cap charged 3.7v to 600000uf) we get 4.8 joules or 480 watts in 10ms discharged. Substantially more power. Possibly not safe.


Well at least I still got the battery holder, fuses, switch and resistor from digikey, plus I ended up grabbing some alligator clips while I was there so I only wasted a couple bucks on the cap.

Breaktru, can you look to find out where he placed his fuse? I see a diode on the wire leads of one of those pics too, any chance there is a schematic floating around for that?

 

[breaktru]

I have a schematic that one of the other guys posted but it doesn't show the converter and the fire and on/off is not correct.
It's a simple circuit if you have to make one. I don't even find a need for a schematic due to the simplicity. A fuse goes where you would put any fuse in any type of circuit.

 

[dsy5]

I think what this thing needs is a one-shot monostable fed into a mosfet that would provide a short burst of current to do the welding. Hit the button and hold the wires together - could even have a short delay before firing to give you time to put the leads together.

Edit: I guess that might not be needed as the cap probably discharges fairly quickly.