In some cases, it is more profitable to use spot welding instead of soldering. For example, this method may be useful for repairs batteries consisting of several batteries. Soldering causes excessive heat cells, which can lead to their failure. But spot welding does not heat the elements as much, since it operates for a relatively short time.

To optimize the entire process, the system uses Arduino Nano. This is a control unit that allows you to effectively manage the energy supply of the installation. Thus, each welding is optimal for a particular case, and as much energy is consumed as necessary, no more and no less. The contact elements here are copper wire, and the energy comes from a regular car battery, or two if higher current is required.

The current project is almost ideal in terms of complexity of creation/efficiency of work. The author of the project showed the main stages of creating the system, posting all the data on Instructables.

According to the author, a standard battery is enough for spot welding two nickel strips 0.15 mm thick. For thicker strips of metal, two batteries will be required, assembled in a circuit in parallel. The pulse time of the welding machine is adjustable and ranges from 1 to 20 ms. This is quite sufficient for welding the nickel strips described above.

The author recommends making the board to order from the manufacturer. The cost of ordering 10 such boards is about 20 euros.

During welding, both hands will be occupied. How to manage the entire system? Using a foot switch, of course. It's very simple.

And here is the result of the work:

There comes a time in the life of every “radio killer” when you need to weld together several lithium batteries- either when repairing a laptop battery that has died from age, or when assembling power for another craft project. Soldering "lithium" with a 60-watt soldering iron is inconvenient and scary - you will overheat a little - and you have a smoke grenade in your hands, which is useless to extinguish with water.

Collective experience offers two options - either go to the trash heap in search of an old microwave, tear it apart and get a transformer, or spend a lot of money.

For the sake of several welds a year, I didn’t want to look for a transformer, saw it and rewind it. I wanted to find an ultra-cheap and ultra-simple way to weld batteries electric shock.

Powerful low voltage source DC, accessible to everyone - this is an ordinary used one. Car battery. I'm willing to bet that you already have it somewhere in your pantry or that your neighbor has it.

I'll give you a hint - best way getting an old battery for free is

wait for frost. Approach the poor guy whose car won’t start - he will soon run to the store for a fresh new battery, and give the old one to you for nothing. In the cold, an old lead battery may not work well, but after charging at home in a warm place it will reach its full capacity.

To weld batteries with current from the battery, we will need to supply current in short pulses in a matter of milliseconds - otherwise we will not get welding, but burning holes in the metal. The cheapest and affordable way switch the current of a 12-volt battery - an electromechanical relay (solenoid).

The problem is that conventional 12-volt automotive relays are rated for a maximum of 100 amperes, and short-circuit currents during welding are many times higher. There is a risk that the relay armature will simply weld. And then, in the vastness of Aliexpress, I came across motorcycle starter relays. I thought that if these relays can withstand the starter current, many thousands of times, then they will be suitable for my purposes. What finally convinced me was this video, where the author tests a similar relay:

We present to your attention a diagram welding inverter, which you can assemble with your own hands. Maximum current consumption is 32 amperes, 220 volts. The welding current is about 250 amperes, which allows you to easily weld with a 5-piece electrode, an arc length of 1 cm, which passes more than 1 cm into low-temperature plasma. The efficiency of the source is at the level of store-bought ones, and maybe better (meaning inverter ones).

Figure 1 shows a diagram of the power supply for welding.

Fig.1 Schematic diagram power supply

The transformer is wound on ferrite Ш7х7 or 8х8
The primary has 100 turns of 0.3mm PEV wire
Secondary 2 has 15 turns of 1mm PEV wire
Secondary 3 has 15 turns of 0.2mm PEV
Secondary 4 and 5, 20 turns of PEV wire 0.35mm
All windings must be wound across the entire width of the frame; this gives a noticeably more stable voltage.

Fig.2 Schematic diagram of a welding inverter

Figure 2 shows a diagram of the welder. The frequency is 41 kHz, but you can try 55 kHz. The transformer at 55 kHz is then 9 turns by 3 turns, to increase the PV of the transformer.

41kHz transformer - two sets Ш20х28 2000nm, gap 0.05mm, newspaper gasket, 12vit x 4vit, 10kv mm x 30kv mm, copper tape (tin) in paper. The transformer windings are made of copper sheet 0.25 mm thick and 40 mm wide, wrapped in cash register paper for insulation. The secondary is made of three layers of tin (sandwich) separated from each other by fluoroplastic tape, for insulation between themselves, for better conductivity of high-frequency currents, the contact ends of the secondary at the output of the transformer are soldered together.

Inductor L2 is wound on a Ш20x28 core, ferrite 2000nm, 5 turns, 25 sq.mm, gap 0.15 - 0.5mm (two layers of paper from the printer). Current transformer - current sensor two rings K30x18x7 primary wire threaded through the ring, secondary 85 turns of wire 0.5 mm thick.

Welding assembly

Winding the transformer

Winding of the transformer must be done using copper sheet 0.3mm thick and 40mm wide, it must be wrapped in thermal paper from a cash register 0.05mm thick, this paper is durable and does not tear as much as usual when winding a transformer.

You tell me, why not wind it with an ordinary thick wire, but it’s not possible because this transformer operates on high-frequency currents and these currents are displaced onto the surface of the conductor and the middle of the thick wire is not used, which leads to heating, this phenomenon is called the Skin effect!

And you have to fight it, you just need to make a conductor with a large surface, so thin copper sheet has this, it has a large surface along which current flows, and the secondary winding should consist of a sandwich of three copper tapes separated by fluoroplastic film, it is thinner and all these are wrapped layers in thermal paper. This paper has the property of darkening when heated, we don’t need this and it’s bad, it won’t do anything, let the main thing remain that it doesn’t tear.

You can wind the windings with PEV wire with a cross section of 0.5...0.7 mm consisting of several dozen cores, but this is worse, since the wires are round and are connected to each other with air gaps, which slow down heat transfer and have less total area cross-section of wires combined compared to tin by 30%, which can fit into a ferrite core window.

It is not the ferrite that heats up the transformer, but the winding, so you need to follow these recommendations.

The transformer and the entire structure must be blown inside the housing by a fan of 220 volts 0.13 amperes or more.

Design

To cool all powerful components, it is good to use radiators with fans from old Pentium 4 and Athlon 64 computers. I got these radiators from a computer store doing upgrades, for only $3...4 apiece.

The power oblique bridge must be made on two such radiators, upper part bridge on one bottom part on the other. Screw bridge diodes HFA30 and HFA25 onto these radiators through a mica spacer. IRG4PC50W must be screwed without mica through KTP8 heat-conducting paste.

The terminals of the diodes and transistors need to be screwed towards each other on both radiators, and between the terminals and the two radiators, insert a board connecting the 300-volt power circuit to the bridge parts.

The diagram does not indicate the need to solder 12...14 pieces of 0.15 micron 630 volt capacitors to this board into a 300V power supply. This is necessary so that the transformer emissions go into the power circuit, eliminating the resonant current surges of the power switches from the transformer.

The rest of the bridge is connected to each other by hanging installation with conductors of short length.

The diagram also shows snubbers, they have capacitors C15 C16, they should be brand K78-2 or SVV-81. You can’t put any garbage there, since snubbers play an important role:
first- they dampen the resonant emissions of the transformer
second- they significantly reduce IGBT losses when switching off since IGBTs open quickly, but are closing much slower and during closing, the capacitance C15 and C16 is charged through the VD32 VD31 diode longer than the closing time of the IGBT, that is, this snubber intercepts all the power onto itself, preventing heat from being released on the IGBT switch three times than it would be without it.
When IGBT is fast open, then through resistors R24 R25 the snubbers are smoothly discharged and the main power is released on these resistors.

Settings

Apply power to the 15-volt PWM and at least one fan to discharge capacitance C6, which controls the relay response time.

Relay K1 is needed to close resistor R11 after capacitors C9...12 are charged through resistor R11, which reduces the current surge when the welding machine is turned on to a 220-volt network.

Without direct resistor R11, when turned on, there would be a large BAC while charging a 3000 μm 400V capacitance, which is why this measure is needed.

Check the operation of the relay closing resistor R11 2...10 seconds after power is applied to the PWM board.

Check the PWM board for presence rectangular pulses going to the HCPL3120 optocouplers after both relays K1 and K2 are activated.

The width of the pulses should be relative to the zero pause 44% zero 66%

Check the drivers on optocouplers and amplifiers that drive a rectangular signal with an amplitude of 15 volts and make sure that the voltage on the IGBT gates does not exceed 16 volts.

Apply 15 Volt power to the bridge to check its operation and ensure that the bridge is manufactured correctly.

The current consumption should not exceed 100mA at idle.

Verify the correct phrasing of the windings of the power transformer and current transformer using a two-beam oscilloscope.

One beam of the oscilloscope is on the primary, the second on the secondary, so that the phases of the pulses are the same, the only difference is in the voltage of the windings.

Apply power to the bridge from power capacitors C9...C12 through a 220 volt 150..200 watt light bulb, having previously set the PWM frequency to 55 kHz, connect an oscilloscope to the collector-emitter of the lower IGBT transistor, look at the signal shape so that there are no voltage surges above 330 volts as usual.

Start lowering the PWM clock frequency until a small bend appears on the lower IGBT switch indicating oversaturation of the transformer, write down this frequency at which the bend occurred, divide it by 2 and add the result to the oversaturation frequency, for example, divide 30 kHz oversaturation by 2 = 15 and 30 + 15 = 45 , 45 this is the operating frequency of the transformer and PWM.

The current consumption of the bridge should be about 150 mA and the light bulb should barely glow; if it glows very brightly, this indicates a breakdown of the transformer windings or an incorrectly assembled bridge.

Connect to output welding wire at least 2 meters long to create additional output inductance.

Apply power to the bridge through a 2200-watt kettle, and set the current on the light bulb to PWM at least R3 closer to resistor R5, close the welding output, check the voltage on the lower switch of the bridge so that it is no more than 360 volts according to the oscilloscope, and there should be no noise from the transformer. If there is one, make sure that the transformer-current sensor is correctly phased, pass the wire into reverse side through the ring.

If the noise remains, then you need to place the PWM board and optocoupler drivers away from sources of interference, mainly the power transformer and inductor L2 and power conductors.

Even when assembling the bridge, the drivers must be installed next to the radiators of the bridge above the IGBT transistors and no closer to the resistors R24 R25 by 3 centimeters. The driver output and IGBT gate connections must be short. The conductors going from the PWM to the optocouplers should not pass near sources of interference and should be as short as possible.

All signal wires from the current transformer and going to the optocouplers from the PWM should be twisted to reduce noise and should be as short as possible.

Next, we begin to increase the welding current using resistor R3 closer to resistor R4, the welding output is closed on the lower IGBT switch, the pulse width increases slightly, which indicates PWM operation. More current means more width, less current means less width.

There shouldn't be any noise, otherwise it will fail.IGBT.

Add current and listen, watch the oscilloscope for excess voltage of the lower key, so that it does not exceed 500 volts, a maximum of 550 volts in the surge, but usually 340 volts.

Reach the current where the width suddenly becomes maximum, indicating that the kettle cannot provide maximum current.

That's it, now we go straight without a kettle from minimum to maximum, watch the oscilloscope and listen so that it is quiet. Reach the maximum current, the width should increase, emissions are normal, no more than 340 volts usually.

Start cooking for 10 seconds at the beginning. We check the radiators, then 20 seconds, also cold and 1 minute the transformer is warm, burn 2 long electrodes 4mm transformer is bitter

The radiators of the 150ebu02 diodes noticeably warmed up after three electrodes, it’s already difficult to cook, a person gets tired, although he cooks great, the transformer is hot, and no one cooks anyway. The fan, after 2 minutes, brings the transformer to a warm state and you can cook it again until it becomes puffy.

Below you can download printed circuit boards in LAY format and other files

Evgeny Rodikov (evgen100777 [dog] rambler.ru). If you have any questions when assembling the welder, write to E-Mail.

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
	power unit
	Linear regulator	LM78L15	2			To notepad
	AC/DC converter	TOP224Y	1			To notepad
	Voltage reference IC	TL431	1			To notepad
	Rectifier diode	BYV26C	1			To notepad
	Rectifier diode	HER307	2			To notepad
	Rectifier diode	1N4148	1			To notepad
	Schottky diode	MBR20100CT	1			To notepad
	Protection diode	P6KE200A	1			To notepad
	Diode bridge	KBPC3510	1			To notepad
	Optocoupler	PC817	1			To notepad
C1, C2		10uF 450V	2			To notepad
	Electrolytic capacitor	100uF 100V	2			To notepad
	Electrolytic capacitor	470uF 400V	6			To notepad
	Electrolytic capacitor	50uF 25V	1			To notepad
C4, C6, C8	Capacitor	0.1uF	3			To notepad
C5	Capacitor	1nF 1000V	1			To notepad
C7	Electrolytic capacitor	1000uF 25V	1			To notepad
	Capacitor	510 pF	2			To notepad
C13, C14	Electrolytic capacitor	10 µF	2			To notepad
VDS1	Diode bridge	600V 2A	1			To notepad
NTC1	Thermistor	10 ohm	1			To notepad
R1	Resistor	47 kOhm	1			To notepad
R2	Resistor	510 Ohm	1			To notepad
R3	Resistor	200 Ohm	1			To notepad
R4	Resistor	10 kOhm	1			To notepad
	Resistor	6.2 Ohm	1			To notepad
	Resistor	30Ohm 5W	2			To notepad
	Welding inverter
	PWM controller	UC3845	1			To notepad
VT1	MOSFET transistor	IRF120	1			To notepad
VD1	Rectifier diode	1N4148	1			To notepad
VD2, VD3	Schottky diode	1N5819	2			To notepad
VD4	Zener diode	1N4739A	1	9V		To notepad
VD5-VD7	Rectifier diode	1N4007	3	To reduce voltage		To notepad
VD8	Diode bridge	KBPC3510	2			To notepad
C1	Capacitor	22 nF	1			To notepad
C2, C4, C8	Capacitor	0.1 µF	3			To notepad
C3	Capacitor	4.7 nF	1			To notepad
C5	Capacitor	2.2 nF	1			To notepad
C6	Electrolytic capacitor	22 µF	1			To notepad
C7	Electrolytic capacitor	200 µF	1			To notepad
C9-C12	Electrolytic capacitor	3000uF 400V	4			To notepad
R1, R2	Resistor	33 kOhm	2			To notepad
R4	Resistor	510 Ohm	1			To notepad
R5	Resistor	1.3 kOhm	1			To notepad
R7	Resistor	150 Ohm	1			To notepad
R8	Resistor	1Ohm 1Watt	1			To notepad
R9	Resistor	2 MOhm	1			To notepad
R10	Resistor	1.5 kOhm	1			To notepad
R11	Resistor	25Ohm 40Watt	1			To notepad
R3	Trimmer resistor	2.2 kOhm	1			To notepad
	Trimmer resistor	10 kOhm	1			To notepad
K1	Relay	12V 40A	1			To notepad
K2	Relay	RES-49	1			To notepad
Q6-Q11	IGBT transistor	IRG4PC50W	6

A time relay timer is a device with which you can adjust the time of exposure to a current or pulse. Timer time relay for spot welding measures the duration of exposure welding current on the parts being connected, the frequency of its occurrence. This device is used to automate welding processes, produce a weld seam, in order to create a variety of structures from sheet metal. It controls the electrical load in accordance with a given program. Programmable time relay for contact welding in strict accordance with the instructions. This process consists of setting time intervals between certain actions, as well as the duration of the welding current.

Operating principle

This time relay for spot welding will be able to turn the device on and off in a given mode with a certain frequency for on an ongoing basis. To put it simply, it closes and opens contacts. Using a rotation sensor, you can adjust the time intervals in minutes and seconds after which you need to turn welding on or off.

The display is used to display information about the current switching time, the period of exposure to the metal of the welding machine, the number of minutes and seconds before switching on or off.

Types of timers for spot welding

You can find timers on the market with digital or analog programming. The relays used in them are different types, but the most common and inexpensive are electronic devices. Their operating principle is based on special program, which is recorded on the microcontroller. It can be used to adjust the delay or on time.

Currently you can purchase a time relay:

• with shutdown delay;
• with delay on switching on;
• configured for a set time after applying voltage;
• configured for a set time after the pulse is given;
• clock generator.

Accessories for creating a time relay

To create a time relay timer for spot welding you will need the following parts:

• Arduino Uno board for programming;
• prototyping board or Sensor shield – facilitates connection, installed sensors with board;
• female-to-female wires;
• a display that can display at least two lines of 16 characters per row;
• relay that switches the load;
• rotation angle sensor equipped with a button;
• power supply to ensure the device is supplied with electric current (during testing, it can be powered via a USB cable).

Features of creating a time relay timer for spot welding on an arduino board

To make it, you must strictly follow the diagram.

At the same time, a frequently used fee arduino uno It would be better to replace it with an arduino pro mini since it is significantly smaller in size, costs less and is much easier to solder the wires.

After collecting everyone components To make a timer for resistance welding on Arduino, you need to solder the wires that connect the board to the rest of the elements of this device. All elements must be cleaned of plaque and rust. This will significantly increase the operating time of the relay timer.

You need to select a suitable case and assemble all the elements in it. It will provide the device with decent appearance, protection from accidental impacts and mechanical influences.

To complete, it is necessary to install the switch. It will be needed if the welding owner decides to leave it unattended for a long time in order to prevent fire or damage to property in the event of an emergency. With its help, leaving the premises, any user will be able to special effort turn off the device.

“Pay attention!

The timer for resistance welding on 561 is a more advanced device, as it is created on a new modern microcontroller. It allows you to measure time more accurately and set the frequency of turning the device on and off.”

The timer for contact welding on the 555 is not so perfect and has reduced functionality. But it is often used to create such devices, since it is cheaper.

To better understand how to create a welding machine, you should contact the company’s employees. In addition, we propose to consider the design of this device. It will help you understand the principle of operation of the device, what needs to be soldered and where.

Conclusion

Arduino spot welding timer is accurate and quality device, which, if properly used, will last for many years. He is enough simple device, so it can be easily mounted on any welding site. In addition, the spot welding timer is easy to maintain. It works even in severe frost, and is practically unaffected by negative manifestations of the natural environment.

You can assemble the device yourself or turn to professionals. The latter option is more preferable, as it guarantees the final result. The company will test the device elements, identify problems, fix them, thus restoring its functionality.

Hello, brainwashes! I present to your attention a spot welding machine based on the Arduino Nano microcontroller.

This machine can be used to weld plates or conductors, for example, to the terminals of an 18650 battery. For the project, we will need a power supply of 7-12 V (12 V recommended), as well as a 12 V car battery as the power source for the welder itself. Typically, a standard battery has a capacity of 45 Ah, which is sufficient for welding 0.15 mm thick nickel plates. To weld thicker nickel plates, you will need a larger capacity battery or two connected in parallel.

The welding machine generates a double pulse, where the value of the first is 1/8 of the second in duration.
The duration of the second pulse is adjusted using a potentiometer and is displayed on the screen in milliseconds, so it is very convenient to adjust the duration of this pulse. Its adjustment range is from 1 to 20 ms.

Watch the video, which shows in detail the process of creating the device.

Step 1: Making the PCB

To make a printed circuit board, you can use Eagle files, which are available at the following.

The easiest way is to order boards from manufacturers printed circuit boards. For example, on the site pcbway.com. Here you can purchase 10 boards for approximately 20 €.

But if you are used to doing everything yourself, then use the included diagrams and files to make a prototype board.

Step 2: Installing components on the boards and soldering the conductors

The process of installing and soldering components is quite standard and simple. Install small components first and then larger ones.
Tips welding electrode made of hard copper wire with a cross section of 10 square millimeters. For cables, use flexible ones. copper wires with a cross section of 16 square millimeters.

Step 3: Foot Switch

For management welding machine you will need a foot switch since both hands are used to hold the welding rod tips in place.

For this purpose, I took a wooden box in which I installed the above switch.