HOMEMADE 600Ws CAPACITOR DISCHARGE WELDER

CAPACITOR DISCHARGE WELDER DOCUMENTS AVAILABLE

2011-07-23T20:19:00.000-07:00

THE CONTROL AND MOSFET BOARDS ARE NOW AVAILABLE 9/2/2011

Here are all the documents to build a fully working micro processor controlled , dual pulse 600Ws capacitor discharge welder. The documents include the processor firmware (Hex file), Gerber files to manufacture the control and the mosfet board, schematics, manuals etc. Look HERE to see what documents are included in this downloadable package.

THE BOARDS AND FILES ARE AVAILABLE BY CLICKING ON THE BUTTON BELOW.

A PEEK AT ALL THE FILES INCLUDED TO BUILD THIS WELDER

2011-07-10T20:26:00.000-07:00

THE DOCUMENT BELOW SHOWS WHAT ARE INCLUDED IN THE DOWNLOADABLE PACKAGE.
UPDATE: THE MOSFET PCB OUTLINE FILE (.GKO)CAN NOW BE DOWNLOADED HERE.

ADJUSTING PULSE 1

2011-06-01T23:02:00.000-07:00

Pulse 1 on this welder is to burn away oil and dirt and pulse two makes the actual weld. I have many guys telling me that they set pulse one much higher to get two welds in one. Unfortunately, that's not how it works. Pulse one will join the two metals lowering the resistance and the energy of pulse two will take the shortest path to the other electrode doing basically nothing. In other words, If a 3ms pulse is enough to adhere the metals being welded and you set pulse one to 3ms and pulse two to 12ms then you will get one weak weld formed by the 3ms pulse and not the 12ms pulse.

To make decent welds with a dual pulse welder you should turn pulse one off and find a voltage and pulse 2 setting that gives you good solid welds. Leave the welder on the determined voltage and set both pulse potentiometers to 0, adjust pulse one to a low setting and make a weld. Keep on adjusting pulse one higher until the metals starts to adhere, decrease pulse one potentiometer about 3%. Set pulse two to the determined setting above and you should get really good welds.

The size of your electrodes and cable to your electrodes makes a big difference. A 4 feet long #0 welding cable will give you twice the current than a 4 Feet #8 welding cable. Do not make your cables shorter than 4 feet though.

UPDATED FIRMWARE AND WELDER FILES AVAILABLE SOON

2011-04-29T22:59:00.000-07:00

I've been working on a new version 2.5 firmware for the Capacitor Discharge Welder and also a package that will contain the newest firmware, gerber files, Bill of materials, manuals and an extra 6 pages to explain how the circuit works and trouble shooting procedures etc. I've included Version 2.1 and version 2.5 in case a bug shows up. Version 2.5 has a change to the charging system, taking the stress off mosfet Q4, slowing the charge intervals and two points on the control board can be jumped with a wire to change the maximum voltage of this welder from 20 to 23.2V. This will increase the energy of the welder from 600Ws to 807Ws. You will need 25V capacitors to use this feature and Diode D10 has to be changed. UPDATE: I'm busy doing some final tests on the firmware. I did not get a very big response about making everything available so I'm going to start by making the updated chips available

If you don't know how to program a processor, you can buy one of these programmers.

This one is $34.95 : K8076 serial programmer

This one is $69.95 : Cana USB programmer

It is as easy as starting the software supplied with the programmer, plug your microprocessor into the programmer, connect the programmer to your computer, load the Hex file and click on "write". It will only take a couple of seconds.

NAVIGATION

2011-04-04T22:27:00.000-07:00

HERE IS AN EASIER WAY TO NAVIGATE THIS BLOG, click on the links below and read the pages from the bottom, up:

THE BLOG STARTS HERE: PAGE 1
PAGE 2
PAGE 3
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PAGE 5
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THIS PAGE: PAGE 7

Pulse Arc Update

2011-02-14T22:10:00.000-08:00

My function generator which came a long way with me went up in a plume of smoke. I had to replace it and bought a Rigol DG1022. It's a nice generator but pricey. I am going to use this generator to play with different waves to see if I can get the correct waveforms for the pulse arc welder. I am thinking of designing a new board from scratch, its already halfway drawn on a piece of paper :). The Budget is also a little low on funds and I will start to buy components as soon as possible. This welder will use much smaller and easy to get capacitors.
These things take time and lots of work so don't expect to see it before the end of this year.

ROGER CARR ~~LET ME KNOW THAT FUTURE ELECTRONICS SELLS THE IRFP2907PBF MOSFETS FOR $3.60~~, THANKS ROGER.UPDATE: FUTURE ELECTRONICS CHANGED THEIR PRICE TO $6.00.....DO NOT BUY FROM THEM!!!!

2011-01-01T01:32:00.000-08:00

HAPPY NEW 2011 EVERYONE

PCB"S ON ORDER

2010-12-08T11:32:00.000-08:00

PCB's ARE SOLD OUT 02/05/2011

PULSE ARC WELDS

2010-11-27T20:07:00.000-08:00

The top three photos was taken when I just started playing with the pulses on the pulse arc welder. The top left photo is two washers welded together, the middle is two strands from a 12 gauge copper wire welded to a washer and the photo on the right is two strands of a 12 gauge wire that were held against the tungsten electrode while firing a 45ms pulse. The bottom two photos were taken after I managed to manipulate and change the pulses to give better welds. The plasma flame produced here is extremely hot.

I have made thousands of welds and adjustments to get this far and will keep on going until I get it to work perfectly. I accidentally made a plasma cutter that cuts through metal when I made the pulses continuous and also managed to weld a copper wire to aluminum.
I'm limited to the metals I have to do further tests however and will appreciate if someone with knowledge of these welders can help me with some advice. Email me at sprbok@gmail.com

PROCESSOR CONTROLLED PWM RELAY DRIVER SCHEMATIC

2010-11-15T20:57:00.000-08:00

When a magnetic solenoid/relay is energized, a magnetic field has to be formed strong enough to pull the plunger in. When this plunger is pulled in, the power can be reduced to a much lower level to keep it in.

This really cool circuit can do the above. If you pull a line, straight down, just before U5 and then build the circuit on the left, you will have a pulse width controlled relay driver circuit that can handle two relays with a total current of 1.5 amps. There are DRV103 IC's that can handle 3 Amps and by changing your power supply to 3 amps, can pull in really big relays/solenoids.

These PWM relay drivers can be activated by supplying 3 to 5V on pin 8 of U2 and U3. The two red LED's will turn on when an over current or over temperature is detected and will shut the IC's down.

This circuit can be changed to drive 12V relays by changing R1 and R2 resistors on the power supply.

When 3 to 5V is supplied to pin 8 of one of the IC's It will turn on fully, supplying 24V to the relay/solenoid and 22milliseconds later (C4 andC5) will start to pulse the voltage at 5000Hz (R3 and R4) and the duty cycle can be changed by adjusting R5 and R6.

R3 and R4 can be changed to get a different frequency, C4 and C5 can be changed if the relay/solenoid needs more time to pull in before a pulsed signal is supplied, just check out the data sheets.

How to adjust:

Put a voltage of 3 to 5V on pin 8 of the DRV103 IC. When the relay pull in, adjust R5 or R6 until the relay fall out. Set it back a little and energize it again to see if it stays in. If the relay doesn't want to pull in at all then replace C4 and/or C5 with bigger capacitors.

THE GERBER FILES FOR THIS BOARD CAN BE DOWNLOADED HERE

THE REAL THING

2010-11-04T22:40:00.000-07:00

I have tested this board and it works as designed

2010-10-22T19:38:00.000-07:00

PULSE ARC WELDER PCB BOARD

This is the prototype board, 4 X 4 inches, that will be driving the Argon and electrode solenoids of the pulse arc stylus.
The white block, printed on the board, in the bottom left corner is the 24VDC power supply and the block at the top left corner is the PWM relay drivers. The area on the rights is the microprocessor circuit.
The microprocessor is going to do a lot of things. It will determine if the electrode is touching the work piece, activate the argon solenoid, calculate the time when to give a pulse to the PWM relay driver circuit to retract the electrode, produce a couple of bleeps and give a pulse to start a pulse arc weld.
This processor will also talk to the other processor in the capacitor discharge welder to make energy pulses possible and much much more.
The PWM relay driver will supply 24V to the relay/solenoid and 22Ms (adjustable) later will give a pulsed adjustable duty cycle. This will reduce the current, preventing the solenoids and electronic driving circuits from overheating.
I'm waiting for the components and boards at the moment and will start doing some test welds soon.

PULSE ARC WELDING STYLUS

2010-09-12T10:13:00.000-07:00

I machined this stylus with my lathe and CNC mill out of aluminum. It compares to the Sunstone Engineering Orion HERE and the PUK 3 pulse arc welders that can weld gold, silver, aluminum, copper, steel, nickel etc. The stylus has a solenoid that retracts the tungsten electrode to start and sustain a very hot plasma arc and argon gas to shield the weld like a TIG welder. This plasma arc is used as a heat source to melt the metal together. Filler rod can also be used to make strong and reliable welding seams.

A123 UPDATE

2010-08-07T14:52:00.000-07:00

These welders have many variables and depending on the size cables, probes and capacitors you used etc. will determine your weld settings. I have done hundreds of welds on A123 batteries and determined that they are no different from any other batteries. When your tabs are too thick to make decent welds, you have to improvise. Current always takes the easiest path and by making dimples and a cut in the middle (picture below) on the tab you are welding will force the current into one dimple, through the battery and out the other dimple. Concentrating the heat on the dimples and produce very strong welds.

You can punch your own dimples and use two pieces of nickel like the picture below.

The probes are also very important, don't use probes with flat tips unless you have a weld head that pushes the probes perfectly flat on the piece that gets welded. Make your tips round on a lathe with a file, like the microscope pictures of my probes below and then use very fine sanding paper to smooth the tips. Rounded tips will make perfect welds every time, won't stick and you can hold the probes at almost any angle.

PULSE ARC WELDING

2010-07-25T10:36:00.000-07:00

I'm looking into adding pulse arc welding to this welder. Pulse arc welding is like TIG welding. By adding Argon gas through a special gun with a tungsten tip will produce a very hot plasma arc that will melt almost any metals together( including aluminum, gold and silver). This welder was originally designed to use a contactor and can easily be converted to activate an argon gas solenoid and a retractable tungsten tip. I will appreciate any input.

ESR TEST AND A123 CELLS

2010-07-03T19:39:00.000-07:00

I have measured the ESR of my welder and its much lower than anticipated. The ESR of the welder bus bars at the front of the welder measures less than 0.0005 Ohm (500 micro Ohm). With such low resistance, this welder can produce astronomical currents and will only be limited by the resistance of the probe, wire and material being welded.
I am way behind schedule with my version 3 processor and spent most of my time getting the new welder built.

Most companies and people out there that are welding A123's are very tight lipped about how they do it and I would like to get to the bottom of it!!! I'm doing some experiments with inverted resistance welding and was wondering if there are some of you guys that would send me some of your old A123's to play with ??? I will post all my findings on here!!!

NEW WELDER

2010-06-23T21:27:00.000-07:00

I started my new welder up today and did a couple of test welds. The welds look really good and much better than my previous welder. I welded some copper to a washer at very low voltages and also checked to see how fine the settings can go by welding 80 micron gold plated tungsten wire to a washer (the photo below was taken with my microscope) and I placed a small BC 847 surface mount transistor next to it. My probe tips are all messed up and I am busy cutting new ones with my lathe which will make much better looking welds. I will also test the ESR this weekend and I'm hoping that it will be in the 0.001 to 0.0015 Ohm range.

WELD POLARITY

2010-06-12T08:51:00.001-07:00

I have many guys asking me why their welders burn holes every now and then and what the big deal is about the polarity of the probes.

Resistance = heat, meaning that the higher your resistance, the more heat you will have. Probe pressure is very important and the harder you push on the probes the better it will make contact and the lower your resistance will be, causing welds that are colder and with too much pressure too cold to melt the metals together. If the probe pressures are not firm enough, it will cause a higher resistance causing too much heat and burn holes. That is why many companies that sells these welders have Weld Heads that are adjustable and make welds when a settable pressure is achieved. That does not mean that we cannot make any good welds by holding the probes in our hands.

Polarities are also very important. when a weld is made it forms a nugget between the metals being welded. This nugget is the melted metal between the two metals that joins them together and you want this nugget to be in the middle of the metals being welded.

When you do a weld the nugget gets attracted to the positive electrode more than the negative electrode and also gets attracted to the metal with the higher resistance. When you weld copper and steel together the nugget will form in the steel with the higher resistance and little or nothing will form in the copper making the copper not stick to the steel or a very weak weld.

A way to move the nugget to the middle of your weld is to always put your positive electrode on the material with the lowest resistance, like copper and your negative electrode on the steel with the higher resistance. If you weld thick and thin metals together you will have to put your positive electrode on the thicker material(thick metals take longer to melt) and your negative on the thinner material.

By looking at the photo below, we can clearly see the electrode positions.

The welds at the bottom of the "stock welds" and " My welds"(I got this pic from a guy that bought one of my boards) are deeper than the top ones and kind of went through the metal, making them weak welds. The positive electrodes were at the bottom of these welds and the negative electrodes were at the top. To overcome the deep welds at the bottom you have to put more pressure on the bottom probes (making colder welds) and put less pressure on the top probes (more resistance = more heat which will make deeper welds).

NEW CASE

2010-05-25T21:06:00.000-07:00

THE 4 SCREW HOLDING THE LCD WAS WELDED WITH MY CD WELDER

CNC CUT OUTS ON MY NEW CASE

UPDATE

2010-05-21T22:48:00.000-07:00

I was promised a case for my welder but it seems like I'm not going to get it after a 5 month wait. I decided to buy the 12 X 12 X 19 case from mouser ($140 including shipping and taxes) HERE. This case is bigger than what I need but I guess it will do for now. I'm going to cut out the face with my CNC milling machine this weekend and rebuild all the circuitry into the new box.
I did some tests on my welder to determine the ESR and Max weld current. I connected 3 X 1 Farad computer grade capacitors with #8 welding cable and got an ESR of 0.0020mOhms. At 20V you will get 10 000 amps. The Mosfet board can handle 15 000 Amps and by using bigger cable, copper bus bars and better connections can increase the current to give you much better and deeper welds than Sunstone Engineering can ever give you for $8000

New Version3 MicroProcessor

2010-04-16T21:00:00.000-07:00

I have been working very hard on a Version 3 Microprocessor for this welder. Version 3 will change this welder from timed pulses to energy pulses. Energy pulses will give you more control of your weld by calculating and adjusting the pulse width automatically to the resistance that you are welding, preventing burned holes due to the wrong probe pressure and a change of resistance. This processor will also have features showing the capacitance of your capacitor and a feature to change the max voltage to 24V.

ORDERING MOSFET PCB's

2010-03-30T18:56:00.000-07:00

I placed an order for more Mosfet PCB's and I should receive it by 4/12/10.

MOSFET PCB's ON ORDER

2010-03-05T20:36:00.000-08:00

I've checked the board for fabrication errors and the only small problem that I could find was that the holes for P1 and P2 are a little small. The terminals still go in with a hard push though and it should not be a problem.
If you look at the board it is hard to believe that it is 3oz copper but by running your fingers over the edges of the copper you can feel the the difference. The board is also heavier. The camera and lights make the silver color on this board look like it is copper.

Mosfet PCB's shipped

2010-03-02T11:18:00.000-08:00

The Mosfet PCB's are on their way to me and should arrive Friday.

BUG!!!!!

2010-02-27T09:26:00.000-08:00

I have a couple of guys that successfully build their welders and are happy with it. However, there is a little bug that showed up. This bug is in the programming that happened in a last minute change to one line of code before starting to ship the processors out. It is more of an annoyance than anything else. By turning your voltage pot up, the set point text on the display will stop at 20Volt. If you keep on turning the potentiometer past this point your capacitor will get charged to a higher voltage and the over voltage protection will kick in and trip U5. The capacitor voltage will start to drop. To reset U5, you have to lower the voltage set point below the actual dropping capacitor voltage and raise the set point up again. If you are rebuilding battery packs and are using a car capacitor, you would never need to go that high with your voltage but for those guys that would like this bug fixed, send me an email and we can work out a way to get your processor updated. Everyone that received boards and processors after 02/15/10 will have the newest firmware already.

Manufactured PCB's

2010-02-15T19:21:00.000-08:00

I have placed an order for the Mosfet PCB's this morning. It had to be sent to an offshore facility because of the 3oz copper and will take about three weeks. I tried to order "OR" boards (some guys said that they will take 1 "or" 2 ) but they didn't have any :)) so I didn't get too many of the mosfet boards. I mentioned in a previous post that I got a price for a 3 layer board that would have solved the weak spot issue on the PCB but it was very expensive. This is a 2 layer board and It has 94 via's that connects the bottom and the top layer. The copper of the bottom and top layer together will be 0.0084" thick. I worked the price out to $80/board + shipping and will sell it on a first come first serve basis.

Manufactured Mosfet PCB

2010-02-12T18:51:00.000-08:00

I changed the Mosfet PCB to a three layer board and I got quotes to have it manufactured. The price was really high, more than $120 per board. I went back to the drawing board and redesigned the 2 layer board to make it stronger with 3oz of copper (took me 2 days). I would just like to know how many of you guys will be interested in this board? The more I buy, the less expensive they get.

Shawn's Tweezers

2010-02-12T00:03:00.000-08:00

SMD BOARD AVAILABLE

2010-02-04T20:43:00.000-08:00

~~I HAVE ONE CONTROL PCB AVAILABLE WITH ALL THE SURFACE MOUNT COMPONENTS INSTALLED~~

Shawns welder

2010-02-03T15:36:00.000-08:00

PCB's ARE AVAILABLE AT THE BOTTOM OF THIS PAGE

2010-01-30T23:45:00.000-08:00

PCB's ARE SOLD OUT 02/05/2011

WELDING PROBES

2010-01-28T08:34:00.000-08:00

This is Shawn's welding probes that he made himself

PCB's

2010-01-23T22:45:00.000-08:00

TOO MUCH TIME

2010-01-23T17:49:00.000-08:00

MOSFET PCB FILES ARE AVAILABLE AT THE BOTTOM OF THE PAGE

2010-01-17T01:26:00.000-08:00

This is a photo that shows the 0.007" stainless steel weld

The mosfet PCB has been strengthened and works really good. I just received 0.007 stainless steel strips and welded it with just one weld to a crescent wrench with a voltage of 12V and a first pulse of 1.2Ms and a second pulse of 7.8 Ms. This weld is so strong that it is impossible to break with your bare hands. I'm going to make the control PCB's available to the people that gave me donations for this project first as promised.

Found It

2010-01-16T07:42:00.000-08:00

We can see how powerful this welder is, It burned the copper. When I designed the Mosfet board I did add via's to connect the top and bottom layers to increase the load this board can take. At the place where it burned, I actually designed it to be connected with 4 wires (shown by the blue lines). The copper burned because it was connected vertically and not horizontally. I will include this in the manual and try to strengthen the copper more.

Thank you guys for all the suggestions about the cause of the copper burning. Everyone thinks that he knows best about what happened. THE PROBLEM AND THE CAUSE WAS FOUND AND REPAIRED. This welder was designed to work with a 3 farad Capacitor and at the time, had capacitors connected in parallel totaling 4.5Farads. The circuit at the top has a gate circuit that divides the top layer in 3 areas that needed to be connected with wires. These areas were not connected and it caused a weak spot on the copper. I took photos and explained in the manual what to do, to make the copper withstand higher current.

How do they say it in the movies?....no components were harmed with this incident :))

Capacitor Size

2010-01-15T19:36:00.000-08:00

As you guys know, I have someone building one of my welders at the moment. He (Shawn) measured the capacitance of his capacitor and came out way short (He is sending it back). Shawn connected 3 capacitors in parallel with a total of 4.5 Farads. He said that the welder worked really good until he cranked it up to 18V with a first pulse of 30Ms and a second of 35Ms when he heard a "pop", That was after about 18 welds. We are trying to find out what went wrong and are in a process of pinpointing the problem. The first pulse is basically just to burn away oil and dirt and the second pulse is the one that does the actual weld. 30Ms for a first pulse is way too high and It might have something to do with the popping sound. When we find the problem, I will redesign and make sure that this never happens again. Hang in there guys, I will keep you updated.

Welder Case

2010-01-06T15:37:00.000-08:00

Shawn sent these photos to show how his welder is progressing. These photos also show the case that we might make available if you guys are interested. He still has to work out what it will cost to make one of these and we might ship them out in different stages of manufacture to make it less expensive, meaning with or without paint, etc. He is hoping to get his welder up and running by next week. Thanks Shawn, it looks awesome!!

Happy new year everyone!!!!

2010-01-01T15:47:00.000-08:00

Thanks for all the support, e-mails and comments Guys. I took some time off to spent with my family over the festival season and are back to finish this project. I have a guy with the name of Shawn building this welder at this moment and I'm using his feedback and questions to write a manual with trouble shooting tips to help with the construction of this circuit. I am busy with the last part of this welder, the Mosfet circuit, and are making it smaller and lining the mounting holes up so the controller board can be mounted on top of the Mosfet board.
For the people that donated, at the bottom of the page, you guys are first on my list! I will be using this money to buy more boards and processors and have it available. THANKS GUYS
I have a very small group of people that are part of this blog and will let you guys have the first choice too.

THANKS GUYS, AND A HAPPY 2010 TO YOU ALL!!!!

Finished Dual pulse video

2009-12-27T22:55:00.000-08:00

WIRING DIAGRAM

2009-12-23T23:27:00.001-08:00

DUAL PULSE CAPACITOR WELDER WIRING DIAGRAM

BILL OF MATERIAL

2009-12-20T20:03:00.000-08:00

DUALPULSEbom4

Please note that the following components were used for version 1 and are not necessary to install for version 2.
Q1, Q2, Q3,
D6, D7
U4
R4, R8, R9, R10, R12, R13, R27
C9

Finished Dual Pulse Welder

2009-12-19T14:56:00.000-08:00

The oscilloscope photo above shows a 12.6 Volt, 5Ms and 15.1Ms weld. Both pulses and the charge times is measured between the two purple lines and is 189Ms which is more than 5 welds per second at this setting.

Photo's

2009-12-13T20:48:00.000-08:00

Left to right : Pulse1, Pulse2 and Voltage adjustment

This took me way longer than expected and I was hoping to have it done by the end of this weekend. The aluminum brackets that the pcb's are on took me most of Saturday to make. I broke two brackets before getting it right and then had a hard time mounting the pcb without making a short. I finally cut all my hard work off and put a piece of wood between the the two cut offs. Bending, drilling and fitting the copper bars took up all of today.
I did however test the dual pulse before tackling this job and I am very pleased with the results. It works better than expected and you can use any one of the two pulses by turning anyone off or use both. At this moment you get two bleeps when you use the dual pulse and one bleep when you use one pulse, it is very fast though and sounds more like a long and a short bleep. It's things like this that needs a little attention.
I will try and have it finished by next weekend and hopefully get it on youtube.

Just a quick update

2009-12-06T11:51:00.000-08:00

I'm done writing the code for the dual pulse and ran it on a simulator but haven't tested it on the welder yet. I took my old welder apart and are in a process of building the new design into that box. I had to cut the Mosfet board and the heat sinks smaller to fit and will post the pictures when I'm done. I was looking into using Joules and Watt Second and not time to control the welder and I will definitely use that to control this welder with a version 3 chip after this one.
What is the difference? Joule and Watt Second will look at the resistance and adjust the time automatically to make better controlled welds and preventing burning holes when the pressure on the electrodes are not same. It will also give you the exact energy release when you are welding different resistances.

ALMOST DONE

2009-12-01T00:01:00.001-08:00

Well, I'm busy with the dual pulse code for the processor and also a couple of bugs that is p***ing me off :)) I guess everyone is asking "why so many Mosfets?". Many Mosfets in parallel lowers the resistance that lowers the heat and increase the amps. The difference between six of these Mosfets and eighteen is a couple of hundred amps more and a welder that is not going to overheat and burn out. You can also see that I get excellent controlled welds at much lower energy rates than commercial welders out there. I'm also turning this Mosfets on and off at precise calculated speeds according to the data sheets to prevent them from going up in smoke.
I'm in the process of ordering more boards and will hopefully be done with the programming by the time they come in to make it available to you guys.

CHARGING SPEED

2009-11-26T13:22:00.000-08:00

The voltage on the left is the actual capacitor voltage and the voltage on the right is the set point. This was just a test with a 19Ohm resistor connected to the discharge terminal causing the discharge to be very slow when the set point is lowered. This will be much faster with a resistor bank with a lower resistance.

PCB TEST

2009-11-22T18:15:00.000-08:00

I've spent this weekend putting the new PCB together( I actually had it built before Friday) and it was very easy to build. You will need magnifying glasses, a good light and a hot air soldering iron for the surface mount components. The rest of the components are soldered at the bottom side and the solder gets pulled into the holes so no soldering is necessary at the top. There are two problems however, I screwed up on the solder mask on the Mosfets and you have to scratch the mask off around the solder points to get a bigger solder area and Diode 10 needs to be turned around.
The charging speed is so fast with a 12 Amp supply that when the capacitor reached it's set point and the mosfet kicks in when the voltage drops 0.1V that it actually overshoots the set point by 0.4V before turning the Mosfet off. I've been writing some really complicated code to try and fix this issue.

THE PCB'S ARRIVED

2009-11-17T19:28:00.000-08:00

Well, the PCB's finally came in. I have a very expensive camera and as you can see I'm not very good with taking photo's. This board is very solid and absolutely of high quality. I don't know why, but my camera makes the middle of the board look like its bent and some of the silver on the board look like it's black.

I will build this board this weekend and post more photos.

2009-11-14T22:01:00.000-08:00

Just a peek at the Mosfet part of this welder. I am still waiting for parts

CAPACITOR DISCHARGING EXPLAINED

2009-11-12T22:45:00.000-08:00

I was browsing the internet and found many sites where the guys think that they will get the same or better welders by making the voltage higher and the capacitance lower. Yes, it will be cheaper and easier to increase the voltage to get more Joules or Watt-second (1/2x capacitance x voltage x voltage) BUT here is the catch: The capacitance of your cap and the resistance that you weld, determine the length of your weld and not the WATT-SECOND. In other words if you have a 1 farad cap, charged to 35Volt (612Ws) then it will completely discharge in 15ms if you weld metal with a resistance of 0.003Ohm (0.005 nickel).
If you increase the voltage to 50V then you will have 1250Ws and your capacitor will still discharge in 15ms at the same resistance.
With a bigger capacitor, lets say 3farad at 20Volt (600Ws), will discharge over a 45ms period.
You can already see what is happening here: A higher voltage will give you more current discharged into your work piece in a shorter time. It will produce more heat, is very hard to control and will make welding thinner metals very difficult, meaning that 0.1ms can give you a nice weld and 0.2 might burn a hole in your work piece.
With a lower voltage and bigger capacitance your weld will be more spread out and will have less current than above but it will give you a much better controlled weld and fuse your metals better and stronger together.
The higher Ws makes a big difference but the capacitance should also be bigger to give longer and better controlled welds.The Volts and Capacitance needs to be balanced to make a good welder.
For battery packs, I will suggest the higher capacitance and that is what I'm building here.

ANY VOLTAGE, 60V AND OVER, AC OR DC CAN KILL YOU! VOLTAGES BETWEEN 50 AND 60V MIGHT GIVE YOU A TICKLE BUT IT WON'T HURT YOU. THIS WELDERS WITH VOLTAGES OF 20V IS TOTALLY SAFE AND YOU CAN HOLD THE PROBES IN YOUR HAND WHILE 10000AMP IS FLOWING THROUGH IT WITHOUT FEELING A THING.

NOVEMBER 6Th

2009-11-06T19:31:00.000-08:00

I finally have 3 boards on order. I ordered only 3 because of the overall high price (tooling amount) and will test them first before ordering more at a cheaper price and also to see how many of you guys will be interested.
I am waiting for parts to build I guess the part of this project that everyone is waiting for. I am trying to make this welder as cheap as possible and this weekend my calculator kept on spitting out data that I didn’t like. I have a circuit that turns my SCR’s off but to build it to work with all big SCR’s out there will be more difficult and expensive than just using Mosfets for the actual weld. I never wanted to use Mosfets but looking at the numbers made me change my mind.
Big SCR’s have an ON resistance of about 1.5mOhm (It differs). If we do a quick calculation you will see that if we make the resistance of the metal that we weld 0(dead short because we are trying to figure out the max current to protect our components) then we only need the Capacitor's ESR and the SCR’s ON resistance to work out the actual max current at the moment the switch is closed (we are not going to use the wire and weld probe resistance because they are variables)
Let’s say our Cap have an ESR of 1.6mOhm. If we use the above SCR and charge our cap to 20V (max) then 1.6 + 1.5 = 0.0031Ohm. I = V/R 20/0.0031 = 6452Amps.
The Mosfets in parallel that I’m going to use will have a much lower ON resistance of 0.0002Ohm which will give us about 11111Amps for a split second(much higher than the SCR). The current will be less if we add the wire and probe resistances and also the metal that we are going to weld. The number of Mosfets in parallel will also give us a much bigger surface area to work with.
I should receive the PCB’s by the 17Th. I am busy designing this new Mosfet circuit and will post pictures and more information ~~Tomorrow~~ when I'm done.

UPDATE OCTOBER 25th 2009

2009-10-25T17:09:00.000-07:00

I have added the over voltage protection circuit and updated the Schematic and 3D board below. I ran the Capacitor charging circuit through some heavy testing and it performed better and faster than all calculations. I designed this PCB in such a way that I can easily add a new feature or change an existing one by just changing the programming on the microprocessor. I have some more tests to do and painstakingly go through every component and hole sizes to make sure everything is perfect before ordering some professionally made boards.

2009-10-13T23:20:00.000-07:00

I've spent a week reading through data sheets trying to find a suitable mosfet driver for this welder. The LTC driver that I selected is kind of an overkill but it works very good. I also changed the code to the Micro in such a way that when the capacitor is completely discharged or at a low voltage it will limit the current to protect the Mosfet and the transformer. I am busy designing an over voltage protection that will turn the mosfet off if the voltage goes over 20V and also a separate over voltage protection for the capacitor if the mosfet fails. The charging speed is fast enough for a dual pulse so I'm kind of throwing the contactor idea away at this moment(still have all the files) and working on making this a solid state welder that will be much cheaper than the $5000 price tag. Hang in there and don't build it yet until I give the go ahead.

2009-09-25T21:31:00.000-07:00

I received many e-mail from people asking me how the capacitor charger work.
If you put, lets say 16V on a capacitor that needs to be charged then it would start to charge very fast and then slow down the closer it gets to 16V (look at a capacitors charging curve).The last 2 to 3 volts can take 75% longer than the first 13 to 14 volts. To overcome this slow down effect we need a more constant current and it's done by increasing the voltage to +- 36VDC (rectified 24VAC). This DC voltage is used to charge the cap and the processor turns the charging mosfet off within 4uS when it reached it's set point (max 20V).
If the set point is lower than the capacitor volts, the processor will turns a mosfet on that connects a resistor bank to discharge the capacitor. EASY HUH?

The photos shows the LCD display with a 1 Farad Pro Ice capacitor that has been charged to 19.1VDC with a switching (processor controlled) rectified 24VAC.

2009-09-13T14:45:00.000-07:00

TAB WELDER 3D UPDATED 10/25/2009

2009-09-11T21:53:00.000-07:00

TAB3d

I made many changes to make this board easier to build. I moved some of the components around to make more space for the heat sinks and I replaced some of the very small surface mount components with bigger ones. I also made some of the circuits wider because they were really very fine and hard to solder without burning them off.

Tabwelder PCB

2009-09-05T23:34:00.000-07:00

I used the hacked Laminator below and the Toner transfer method to make this double sided beauty. CLICK ON THE IMAGE TO SEE A FULL SIZE PHOTO. TO ZOOM IN AND OUT CLICK ON THE IMAGE, HOLD YOUR CTRL KEY AND ROLL YOUR MOUSE WHEEL. IN CASE YOU DIDN'T KNOW THIS, YOU CAN ZOOM IN AND OUT ON WEB PAGES AND DOCUMENTS ON YOUR COMPUTER BY USING THIS TECHNIQUE.

UPDATED SCHEMATIC

2009-08-29T23:59:00.000-07:00

Homemade Capacitor Spot welder

2009-08-27T21:11:00.000-07:00

18V Dewalt Battery pack

2009-08-12T09:41:00.000-07:00

Battery packs are very expensive. With this Capacitor discharge welder you can build your own battery packs cheap. This is the only welder that has Pulse width control on the internet.
I'm busy with step by step instruction and a schematic to build this welder. I'm done with the control schematic and will post it soon. The above photo's are a rebuild DeWalt 18v battery pack that cost me about $20....a new pack would have cost me $94 + tax.

PCB LAMINATOR HACK

2009-08-11T20:30:00.000-07:00

This is a very small PCB that I made with the hacked Laminator (just testing and not putting much effort in to make it look good) and the tracks are very small (11 mil or 0.3mm). There is one place where the tracks are touching but by looking at my PCB program the track clearance was set for 2mil and that is way too small.
PCB's up to 1.6mm will go through. Go here to see how to make crisp good looking PCB's with the toner transfer method using this laminator.
Unfortunately I could only find one component at Digikey and one at Mouser but you might have more luck finding both at one place on the web. The thermal fuse was $0.99 and the Thermostat $4.50. The thermal fuse is there for a final protection before the unit catches fire. You can just take the fuse out and connect (jump) the two wires but like PodeCoet said "don't forget to send me photos when it catches fire"

I've been making PCB's for years and I had different ways of making them, including using a router, like my video below. My router's PCB's came out really good but it took hours of setting the machine up and then watched it in slow motion cut the tracks. The circuits is actually called isolated circuits and it makes it very difficult to solder small surface mount parts. One little drop of solder falling between the isolated track underneath a component and it takes hours of finding it. I was looking around on the internet and found an interesting web site that uses the Toner Transfer Method and a hacked Laminator to make really good looking boards. You can find PodeCoet 's hacked Laminator here. He was using an Australian laminator and added a resistor in series with an electronic temperature control to make the laminator warmer. I looked around and found a GBC Personel laminator at Digikey for $69 + tax and shipping(not converted). Way too expensive for me! I found the same one on E-bay for $24, no tax and free shipping and converted it to a warmer 338F temperature for a couple of bucks more. Look at the photos above how to hack a US laminator and PodeCoet's site for more information. CLICK ON THE IMAGES TO SEE A FULL SIZE PHOTO

2009-08-01T23:03:00.000-07:00

2009-06-28T00:41:00.000-07:00

Welding a paperclip to tweezers

10 Volt 15.2 Millisecond weld

2009-06-27T23:42:00.000-07:00

2009-06-20T00:37:00.000-07:00

I made this Hand held attachment with my CNC machine

2009-06-13T09:26:00.000-07:00