KaeptnBalu

The hole is not missing. It was removed intentionally to have more space for copper area on the bottom of the pcb. The middle leg of the mosfet is not needed. It can be soldered to the middle pad or just be cut off.

You can also use 1206 format. 1210 was just easier available foe me.

It does not have to be exactley this 1uF film capactor. You can use anything from about 1-10 uF with at least 16V voltage rating.

Copper would be even better than the Aluminum. Its just much more expensive and harder to machine while electrical propertys are not that much better compared to copper. Thats why the elements are made out of aluminum.

Its pretty simple. If you touch the nickel with both welding tips there will be 12V from the car battery at D3. Since this would be to much for the Arduino Nano there is a zener diodes that limits this voltage at D3 to about 4 V.

Hi, the welder only works in a range from 10 ... 14V. You can use 12V car battery or 3s Lipo only.

You could change the voltage regulator on the Arduino Nano, but a new Arduino Nano is only about 3$, so i would change the complete thing. The Arduino Nano can just be unplugged from the pin headers to put in a new one.

This could have killed the 5V regulator on the Arduino Nano. It is a linear regulator, so it can not handle high voltages very well. The mosfet driver should be ok. It has a maximum input voltage of 18V according to the datasheet.

Hi,I can remove the Arduino Nano. But this will only reduce the total price by 4 €. If you want to get a Spot Welder Kit without the Arduino please write to info@malectrics.eu

You need the 1s version

Hi,this should be no problem. They have almost identical specs and the same pinout.

Sorry, i totaly forgot to upload the files. They are now on my Github: https://github.com/KaeptnBalu/Arduino_Spot_Welder_V3/tree/master/KiCad_PCB_Files/Gerber

If you want to use capacitors please read this article: https://www.thingiverse.com/thing:2588371The 8 power fets need quite some current to switch fast. The microcontroller can only provide about 10mA reliable at the I/O Ports. So it is best for reliability and function to use a dedicated mosfet driver IC like the MCP1407.

I also noticed that problem. The BOM and mouser shopping cart link of V3.2 has already been updated. Alternative Diode is this one: https://www.mouser.de/ProductDetail/Vishay/SMC5K13AHM3-H?qs=sGAEpiMZZMvxHShE6Whpu669Q5WayNPxggMm9nxlrLI=It is a Vishay SMC5K13AHM3/H

Did you built it yourself ? Maybe something is connected wrong or you got a defective mosfet. I did several hundred welds back in the day with my V1 unit and had very consistent welding results.

Should be no problem. Maybe you will get some sparks at the welding tips.

This will most likely be the 2 nickel strips not touching each other. Then the current goes completely through one single nickel strip and you burn a hole in it or get some big sparks at the welding tips.

This was because of the big shottky protection diode. After some time i found out that it has a leakage current highly depending on temperature. So in most cases it worked fine at room temperature (22° C) but when working at higher temperatures like 30°C the 620 ohm resistor was to big to clamp this leackage current to ground. With the 150 Ohm resistor it does work even at very high temperatures. But in the V3 you dont need the schottky diode for protection anymore, because the TVS diode mounted directly on the pcb is much more effective than connected with wires like on the previous versions. The TVS only is now enough to protect the mosfets. So the value of the 150 Ohm resistor could be higher with no problems. But i decided to leave it 150 Ohm so if someone decides to still use…

This was because of the big shottky protection diode. After some time i found out that it has a leakage current highly depending on temperature. So in most cases it worked fine at room temperature (22° C) but when working at higher temperatures like 30°C the 620 ohm resistor was to big to clamp this leackage current to ground. With the 150 Ohm resistor it does work even at very high temperatures. But in the V3 you dont need the schottky diode for protection anymore, because the TVS diode mounted directly on the pcb is much more effective than connected with wires like on the previous versions. The TVS only is now enough to protect the mosfets. So the value of the 150 Ohm resistor could be higher with no problems. But i decided to leave it 150 Ohm so if someone decides to still use the schottky diode on the V3 it will work.

The schottky diode is not that important. But i would recommend to at least install the TVS diode to protect the mosfets.

M2.5 screws are fine. I will update this in the instructable.

There is no need for conductive grease. I already did several thousand welds with the aluminum parts directly bolted to the pcb.For the super capacitor solution check out this article on thingiverse. This guy put much effort into it and seems to work good.https://www.thingiverse.com/thing:2588371As a Lipo battery i use this one: https://hobbyking.com/en_us/turnigy-battery-nano-t...It is about the same welding power as a 400CCA car battery. Has about 3000 welds (4 charges) on it now with no signs of degradation. But the ones you listed could also work.

It also works with just the TVS.

The 9V battery should work. Most of the current for the mosfet drivers is supplyed by the capacitors on the pcb, because they only need the high current for a very short time. The normal current draw of the Spot Welder is arround 100mA.

It will also work with the 3s 5000mAh Lipo. 4s is not good because the Welder is designed for 12V batteries. I also had the idea with a OLED display and little menu system. This way you can change settings directly on the Spot welder instead of changing it in the Arduino code. Already working on it. But this addon needs a complete new pcb layout and new Arduino program. So it will take some mor weeks till it is ready.

Both Mosfet types will work. The IRFB7437 can handle a little bit more current and have a better avalance current rating. So they should be more robust than the IRf1405. If you are using the recommended arround 400 CCA car battery type it doesnt matter which ones you use.

Dang it, the part number was wrong in all the BOMs. Sorry for that. I updated the BOMs so it is correct now.

The voltage drop of the car battery is not the problem. That should be compensated by the capacitors next to the mosfet driver.But at the end of the pulse there is a voltage spike that reaches about the voltage rating of the mosfets. So arround 50V for the IRF1405 mosfets. It is only few micro seconds short but could damage the components on the Arduino board. If you are using the 2 protection diodes the voltage spike is even shorter. So it may work then to power the Arduino Board from the car battery without blowing something up. Have not tested it.

Remove the AutoPulse Jumper and then put the Test Code on the Arduino.https://github.com/KaeptnBalu/Arduino_Spot_Welder_...Then you can measure all voltages with a normal multimeter. More detailed instruction is on Github: https://github.com/KaeptnBalu/Arduino_Spot_Welder_...

Resistor R13 does not need to be populated. It was meant as a pull down resistor, but after looking close to the schematic i realised R14 + R15 already do the pull down to GND. In the latest PCB files on Github i removed R13. So in the next batch of PCBs there will be no R13. I have not received the new PCBs yet, so pictures are not updated.

Hi, i updated the website. The Paypal problem should be fixed now. Thanks for the info.

Hi, The welder needs about 400A to function properly. But a normal fuse will not work in this application. If you use for example a battery that can deliver 440A, the welding current for the set pulse time will be close to 440A. So in case of a defective mosfet for example the current will still be 440A but for a longer time.

Just finished my new website. You can get pcbs there if you like.https://malectrics.eu

The cable for the diodes should be 10mm² ( 7 or 8 awg). For the tvs diode you can also use thinner cable if it is just a very short piece.

Since the new version only has one driver for all mosfets, each of the mosfets should have its own gate resistor. On the V1 each mosfet had its own driver output and therefore gate resistor were not as critical as on the new v2.

Matze, that is an awesome construction you made there. Love it.

Use IRF1405 https://www.reichelt.de/Transistors-IRC-IRF-/IRF-1...IRF3704 can not carry enough current.

M3 x 10mm fit perfect if your aluminium is 4mm thick

I did some measurements and with the shottky diode only there are crazy voltage oscillations which make the spot welder freak out. You can see it in the step i added to the instructable. With Shottky+ tTVS everything works fine.

I will do some oscilloscope tests soon. And if its good add the diodes to the future prebuilt kits. You can already get them on my tindie store f you want to upgrade your existing spot welder. I do also have a little wiring diagram there. https://www.tindie.com/products/KaeptnBalu/diy-arduino-battery-spot-welder-diode-set/

That was related to the old version of pcbs that had a little mistake in the solder stop. No need to pay attention to this with the newer boards.

You can use any non inverting dual drivers which can handle 12v supply voltage and ttl (5v) control signal.

And important: make sure they have the same pinout as the mcp14e10 drivers

If you plug in the Arduinos USB it powers the welder with 5v so you can test if the display and led works. But for welding you need to connect 7...12V to the 12V input pin and negative(GND) to the GND pin. Don't use the car battery to power it, use a seperate power supply or a little 2-3s lipo battery.

Do you have a link to the thread with the information so i can take a look ?I have done several hundres welds with the spot welder and there was no problem so far. Therefore i did not think about adding more parts to it.

Did you check the mosfet drivers ? If always a pair of mosfets blows up, maybe it is a bad driver because there are 2 mosfets conencted to each driver.

Better use a seperate power supply. 1A 12V should be enough. Or use a 2-3s Lipo battery.

Hi Seegers, The display changes between the two digits about every second if you are higher than 9 ms. For example if you adjust it to 14ms it shows 1 , 4, 1, 4, 1, 4, 1, 4 ....

The IRF1404 also works. I used the IRF1405 because it is rated a little bit higher Amps but costs the same as the 1404 here in Germany.

Arranging and packing all the parts is allmost the same amount of work as soldering them to the pcb. So i decided to make some prebuild kits instead of part sets.

Hey guys, I do currently have some PCB Sets an 3 prebuilt kits in stock. Take a look here:https://www.tindie.com/stores/KaeptnBalu/

The Arduino typically comes with pins and sockets. So you only need one 8 Pin header and socket and 2x 2 pins and sockets for the ground connection (JP1 and JP2) of the two pcbs.

Thank you for pointing out the problems. I updated step 3 of the instruction so hopefully its more clear now.Ps: the Arduinos i ordered came with the 6 Pin header pre installed. I was just to lazy to unsolder them.

Typically, when you buy the Arduino it comes with pin headers. So you only need one extra 20 pin row for all the rest pins.