Comments on: Capacitor Discharge Microspot Welder / Cutter

By: David

David — Wed, 01 May 2013 19:10:11 +0000

Radu: Sure, I can send you some pictures. Unfortunately, I don’t have a site yet. By the way, I can’t find an email address for you on this site. How do you recommend I forward the pictures?
Thanks David

By: Radu

Radu — Wed, 01 May 2013 08:59:34 +0000

Hi David, can you send some pictures? I’d like to include them in the article: maybe a link to your site too?

By: David

David — Wed, 01 May 2013 05:39:58 +0000

Radu: Thanks for the well documented C code. I finally got things sorted out with a few changes. Again, thanks for taking the time to share your efforts and recoding Jiri’s code in C++. I still have a few minor problems, but that’s due to the initial design by UltraKeet. Otherwise, I’m pretty happy with the results. Take care. @Leonard Hack: No this code won’t work for Fritz project. @Jason: I wouldn’t change Q1 emitter if your Vcharge supply is greater than 20V. The IRFP2907 has a max gate Vgs of 20v so be careful there. Another option is to change Vdrive supply 15V regulator to a 18V regulator. This will give you a max charging voltage of 13.8V instead of 10.8V. Unfortunately, that is probably the best option without having to redesign the Vcharge section with a P-channel MOSFET. Good luck guys. David

By: Leonard Hack

Leonard Hack — Tue, 02 Apr 2013 05:45:15 +0000

I would know if the code you write is compatible with spot welder of Fritz Geyser.
Best regards.
Leonardo

By: David

David — Mon, 01 Apr 2013 06:55:43 +0000

Hi Radu: No need to reply. All the information I need is in the source files. I guess I should have started there before posting. Thanks David

By: David

David — Sat, 30 Mar 2013 20:30:37 +0000

On my PCB, J12 header had pin 6 and 8 shorting. Once, I fixed that issue, I can’t quite understand what your code is displaying on the LCD. I believe there are still some issues with the code. For example: On line1 the left column number never clearly forms a solid numeric number. It is updating so fast that you can barely make out the value. The second problem is the menu button if pressed multiple times, will cycle between the two modes than a third press of the button will generate random characters throughout the LCD display. Thirdly, the menu left right buttons only work on the middle column on line1 to increase or decrease the shown value. I am guessing I can mod the code if you could provide a brief explanation of what the LCD positions and values represent. Here is what I think the LCD is showing: line1 “Current Capacitor Voltage”, “Target Voltage”, and “Power supply voltage”. line2 “Pulse 1 duration”, delay between pulses, and “finally Pulse 2 duration”. Also, maybe some example setting values for those of us who are blindly attempting to complete such a project for the first time. Please understand that I am not complaining and appreciate all the time and effort you have put into this project, but at the same time regardless of an individual experience level, some clarity is always welcome. Thanks David

By: Radu

Radu — Sat, 30 Mar 2013 09:24:05 +0000

Hi David, what was the problem?

By: David

David — Sat, 30 Mar 2013 03:16:18 +0000

Disregard my previous post problem resolved. Thanks

By: David

David — Sat, 30 Mar 2013 00:58:10 +0000

Hello Radu: I am trying to finish up things here, but I’m having some problems with the LCD. When I load the code that you provided above, I am getting garbage on the LCD display. Any idea what is going wrong here. Of course, I am using a HD44780 display as recommended and the processor fuse bits are lfuse=”ff” and hfuse=”c9″. Thanks

By: Radu Motisan

Radu Motisan — Mon, 04 Mar 2013 20:02:57 +0000

Salut Florin,

Chiar ma gandeam recent ca de as avea timp as face unul mai mic, mai compact, cu piese mai ieftine.

Dar daca ti-e ok asa, te incurajez sa-l faci, eu il folosesc de fiecare data cand trebuie sa imi lipesc cate un pachet de baterii. Apropo, e destul sa folosesti si doar 3x IRFP 2907 .

Daca ai intrebari, poti sa le postezi aici, cand pot te ajut.

By: Florin

Florin — Mon, 04 Mar 2013 16:32:39 +0000

Deci Radu estiiiiiii “bestial” imi place proiectul tau ,l-am gasit cam tarziu , dar ma apuc de treaba, multumescc
ca l-ai facut public si pentru oameni care nu pot concepe “adica je”dar potsa-ti urmeze instructiunile si sa duca proiectul la capat.
Miii de multumiri!!!

By: Radu Motisan

Radu Motisan — Wed, 20 Feb 2013 21:19:14 +0000

Salut Iamandi,

Ma bucur ca mi-ai scris. Partea de scriere a hex-ului nu e chiar atat de grea, si sper sa te pot indruma sa o faci cu succes. Eu folosesc programatoare ca si acestea: http://www.pocketmagic.net/2012/05/cheap-avr-usb-programmer/

Softul cu care scriu .hex-ul e WinAVR, dar e mai greoi de folosit pentru ca e in linie de comanda. Eu ca programator, sunt obisnuit. Iti pot recomanda “Extreme burner” care are interfata grafica.

Cat despre fuses, o sa pun un articol cu mai multe detalii, pentru ca mi-am dat seama ca am omis aceste aspecte in mai toate articolele mele si lumea are nevoie.

By: Cristian

Cristian — Wed, 20 Feb 2013 19:27:14 +0000

salut Radu,
Iti scriu urmatoarele ptr ca m-am impotmolit cu acest proiect . Cu programarea stau in pom si pomul e in aer . De o saptamana ma tot chinui sa programez ATmega16 si fara success. spune-mi te rog ce programmer sa cumpar si ce software sa folosesc pt programarea MCU. prima mea increcare a fost cu ALL-100A Universal Programmers bine-n-teles fara a scrie si Fuses , rezultatul a acestei incercari a fost un blank screen si a flashing led. La a doua incercarea am folosit pony programmer si AT-Prog.
Multumesc si astept cu nerabdare sfaturile tale.
Cu respect Iamandi

By: Radu Motisan

Radu Motisan — Thu, 31 Jan 2013 20:39:19 +0000

@Jason, the software is set to increase/decrease the voltage on the capacitor in 1V steps.

To charge your 1Farad cap to a higher voltage, you will need to make a change to your device: connect the emitter of Q1 to Vcharge instead of Vdrive.

Please detail the following: “in your usWelder.hex file, have you also taken consideration for a contact debounce switch delay of approx. 20 to 30 msecs for increamenting / decreamenting the target voltage setting and mode selection setting?”

Regarding the 4th pot, it is currently unused, but planning to use it instead of the push buttons, for selecting the target voltage.

Don’t forget to send me pictures with your setup, I’m very curious to see it!

By: Jason

Jason — Wed, 30 Jan 2013 19:04:10 +0000

Hi Radu,
I just finished with your project and works amazing with the fuse bit settings as you have mentioned.
Some points I want to clarify is that the target capacitor voltage only increases / decreases in steps from 0.3,1.3,2.3….12.3,13.3 volts and vice versa (the top center LCD part) is that correct?
Secondly, my 1 Farad cap. voltage doesnot go beyond 10.8 volts, no matter what if I set the target voltage to 11.3, 12.3 or 13.3 it stays the same, my input charging voltage is 22.6 volts DC @ 8 amps current.
Is that normal too or I have done something wrong in programming?
Thirdly,in your usWelder.hex file, have you also taken consideration for a contact debounce switch delay of approx. 20 to 30 msecs for increamenting / decreamenting the target voltage setting and mode selection setting?
I have seen in your website photos you have incorporated 4 potentiometers first for Pulse1 second for Delay and third for Pulse2. What is the 4th potentiometer for?
Thanking you once again for this superb project.
Regards,
Jason.

By: Radu Motisan

Radu Motisan — Mon, 28 Jan 2013 19:02:50 +0000

@David, it’s the drain going to capacitor positive terminal. Seems like the symbol is wrong. Also See: http://www.irf.com/product-info/datasheets/data/irfp2907.pdf

@Jason, thanks for reminding me to talk about the fuses. I don’t know how I forgot , probably I don’t pay much attention to this details. Anyway, here’s the fuze configuration, setting the atmega16 for an external , high frequency crystal (16MHz): avrdude -p atmega16 -c USBasp -U lfuse:w:0xff:m -U hfuse:w:0xc9:m

By: Jason

Jason — Mon, 28 Jan 2013 18:38:12 +0000

Hi Radu,
I have almost 90% completed the circuit and assembled the boards as per your instructions.
Your project is just amazing, and thanks for sharing the info. including the source code.
One question, if I program the ATMega16 using ATMEL AVR Studio 6.0 and usWelder.hex, what should I set the fuse bit hi and low settings?
Please give me detailed info. as regards this matter.
Thanking you,
Jason

By: David

David — Sun, 27 Jan 2013 02:58:51 +0000

Hi Radu, Getting pretty close to assembling my parts, but I need to clarify one connection on the schematic. What pin are you connecting from Q7(IRFP2907) to the capacitor’s positive terminal? I am a little confused because the IRFP2907 symbol is upside down on the schematic. I would rather not guess which pin is implied here. Thanks as always.

By: David

David — Fri, 18 Jan 2013 14:24:32 +0000

Radu, Thanks, I appreciate the quick response. Have a great day.

By: Radu

Radu — Fri, 18 Jan 2013 14:09:59 +0000

david, they are all simple momentary push buttons.

s2,s3,s4 are mounted in the case, as seen here :
http://www.pocketmagic.net/wp-content/uploads/2012/02/kwtubes-3.jpg
and http://www.pocketmagic.net/wp-content/uploads/2012/02/welder_ready-3.jpg
and serve to control the software menu

s1 is mounted on one of the electrodes, and is used as a trigger for welding and cutting:

By: David

David — Fri, 18 Jan 2013 14:05:28 +0000

Hi there, I am in the process of ordering all the parts needed for the project, but I cannot find any information on the schematic stating the type of switches used for S1…S4. Could you be so kind and tell me what type of switches did you use? Thanks

By: Radu Motisan

Radu Motisan — Tue, 08 Jan 2013 22:00:37 +0000

See PART 6: Components used for costs.

By: Nitrous

Nitrous — Tue, 08 Jan 2013 21:50:54 +0000

What did this project ultimately cost in parts?
It looks like it could make a great power supply for a wire EDM.
Thanks for sharing.

Nitrous

By: Radu

Radu — Sun, 06 Jan 2013 09:23:31 +0000

@David, I’ll try to find time to publish an updated version of this project, including newer source code. But until then, please do the PCB changes yourself. It is trivial for the power supply section.

By: David

David — Sun, 06 Jan 2013 01:32:16 +0000

Hello Radu, I am trying to sort out the PCB layout and Schematic that were provided from the download links above. There seems to be a few discrepancies between the two. For example I can not find the IRF2807s anywhere on the PCB layout. I do not want to move forward until I fully understand the relationship between the two. I am guessing you may have made some changes, but did not update the PCB layout or the actual PCBs. Another example is the power supply sections on the schematic: It shows three sections to the power supply and the PCB layout only shows two. can you add some clarity? Again, I appreciate your time and effort. David

By: Radu Motisan

Radu Motisan — Wed, 02 Jan 2013 22:32:39 +0000

thanks. happy new year!

By: David

David — Wed, 02 Jan 2013 11:32:19 +0000

I’ll post any success that I may have putting to unit together. Let me say this, I appreciate all your work and time that you have contributed to this project especially looking of the cost of a commercial unit of this type. Happy New Year!

By: Radu Motisan

Radu Motisan — Wed, 02 Jan 2013 11:08:03 +0000

The PCB is in PDF format, attached at the end of the article.

By: David

David — Wed, 02 Jan 2013 10:38:03 +0000

Thanks for the quick response, I’ll look over the schematic. By the way, are there any Gerber or PCB files available on your design? Thanks in advance.

By: Radu Motisan

Radu Motisan — Wed, 02 Jan 2013 09:25:39 +0000

David, the principle is the same, the uC simply produces pulses delivered to the switching board. Please look over the schematics, to compare the content resulting in the BOM list.

By: David

David — Wed, 02 Jan 2013 09:18:30 +0000

Hi Radu, I have followed this project across a few different sources(yourself, Jifi, UltraKeet) and would like to built your version. Just need to know whether the BOM supplied by Ultrakeet will work with your design? Of course excluding the PIC processor. Thanks

By: Radu Motisan

Radu Motisan — Wed, 14 Nov 2012 08:50:38 +0000

Indeed, Ryan, this is correct. Thanks for an excellent remark!

By: Ryan

Ryan — Wed, 14 Nov 2012 03:15:12 +0000

You might try increasing the voltage you are charging your capacitors at. By running your system at higher voltages, you can get a more consistance arc to your material at greater distances, making continuous cutting more reliable. Be careful not to raise it too much though, because you want to be able to control the location of your spark.

By: Radu Motisan

Radu Motisan — Tue, 13 Nov 2012 05:26:57 +0000

Ciao Maurizio,

See pictures from Part 3: February 22nd, 2012 and newer. They show the latest version.

Good luck!

By: Maurizio from Italy

Maurizio from Italy — Mon, 12 Nov 2012 23:16:50 +0000

Great work!
Would be nice to have an overall pattern of assembly or, at least, some pictures of the latest version. Thank you very much

By: Radu Motisan

Radu Motisan — Mon, 01 Oct 2012 09:17:54 +0000

I’ve used it for corroding some small PCBs a few times.

By: jon

jon — Sun, 30 Sep 2012 21:57:23 +0000

have you considered using this as a power supply for a simple edm setup?

By: Luis SIlveira

Luis SIlveira — Mon, 03 Sep 2012 16:38:17 +0000

I first just want to thank you for sharing all your hard work. I am a noob and I cant find your pcb layout for the 5 mosfets. Any help will be greatly appreciated.

Thank you and great job.

Luis

By: Radu Motisan

Radu Motisan — Tue, 21 Aug 2012 07:04:40 +0000

@alberto: I’m glad it proves useful!

By: alberto

alberto — Sat, 18 Aug 2012 03:38:56 +0000

just wanted to thankyou for all the hard work you are doing and for making this open source so everyone can benefit really nice work.

By: Scooter Zamboni

Scooter Zamboni — Wed, 15 Aug 2012 06:45:38 +0000

I find this post very informative and would like to learn more about the capacitor and how it’s used. However, can you make the terms less technical? Thank you.

By: Carlos

Carlos — Fri, 20 Jul 2012 05:36:44 +0000

hello Radu Motisan
What is the maximum and minimum time of the 1st pulse, the 2nd pulse and the waiting time between two impulses?
which the frequency of charging and discharging in the cutting mode?
thank you

By: Radu Motisan

Radu Motisan — Wed, 18 Jul 2012 07:19:59 +0000

Hi Carlos,

The soldering works like this (you can also see it in the code):
PIN PD5 turns high , to command welding, for a very short amount of time, predefined using the user interface.
Then it waits for a short delay, predefined as well.
And finally a second pulse follows.
This is why you can call this dual pulse spot welding.

The cutting works by sending pulses repeatedly.

The charging of capacitors is controlled by bringing HIGH the pin PD4, it will command the Q2 mosfet, that charges the capacitor.
The discharge works in a similar way, bringing high the pin PD6, that opens the Q5 mosfet, that dumps the capacitor energy into the R13 power resistor.
The voltage on caps is measured using the ADC4 port, with the voltage divider made by resistors RVR2A and RVR2B.
The user can select the desired voltage in the interface, the software will continuously check it, and charge the capacitor or discharge it as need it, by controlling Q2 and Q5.

Let me know if you have any other questions.

By: Carlos

Carlos — Wed, 18 Jul 2012 07:02:36 +0000

hi Radu Motisan.
Your project looks very good.
I would like to make a similar but with a PIC16F877.
Possive of you will be doing a description of your project both the cutting level as solder? How do you control the voltage of the capacitor?
Thank you and good continuation of projects

By: Radu Motisan

Radu Motisan — Tue, 17 Jul 2012 16:55:58 +0000

@Open Source. All details shared, as I took some time to draw the diagrams. Hope this helps

By: Radu Motisan

Radu Motisan — Wed, 11 Jul 2012 18:01:20 +0000

If you look at my other posts you will quickly see that I share not only full design and schematics, but source code is also always included. So no reason to complain here.

I’ve got lots of things on my head and doing all of them as quickly as I can. I plan to post the schematics for this setup, but drawing them takes time.

Your patience is much appreciated. Thank you.

By: Open Source

Open Source — Wed, 11 Jul 2012 17:08:18 +0000

Whatever.

This guy doesn’t share, period. He’s into glory, not the greater good. I wouldn’t waste time looking for schematics or code. What looks like a cool invention is just one man’s implementation of well-known prior art; maybe you could pay him for the details.

Or not.

Anyway, this is F’ing trivial to do, and all you have to do is google amateur EDM or capactive discharge machining. It’s basically the opposite of welding. You also don’t need a micro to do it, you can create PWM waveforms from trivial analog circuits and some gates.

Here’s a start, using a PIC programmed in BASIC. Mind you, these people are not exactly rocket scientists, but they don’t treat everything like a top secret VC wankfest, either.

http://bbs.homeshopmachinist.net/showthread.php?t=32118

By: Carferre

Carferre — Sun, 01 Jul 2012 04:08:34 +0000

Radu hello.
Your project and very good, was a welder this type that I needed.
He is working well?
You said you would here the schematics and firmware soon, and that when you put them?
Thank you and good continuation of projects

By: Radu Motisan

Radu Motisan — Fri, 15 Jun 2012 08:16:02 +0000

Thanks for reminding me to do that . I’m still caught with a lot of work, hope to find some time for it soon, hopefully before I forget all the details

By: Storm

Storm — Fri, 15 Jun 2012 04:04:54 +0000

Good morning,Y am working on a pulsator magneto kinetic personal project witch is using chocks and percussion mechanic effect.This project need shorts electricals impulsions(between 0.10 to 0.001 second)with a maximum intensity.Can you let me know what are the limits of your impressive system? I hope you upload the schematic soon