home · Networks · Diagram of a Gauss gun. The simplest Gauss gun without capacitors. RailGun or in our opinion Railgun

Diagram of a Gauss gun. The simplest Gauss gun without capacitors. RailGun or in our opinion Railgun

An electromagnetic rail rifle, commonly known as a Gauss gun, cannot be found in a weapons store. It does not leave cartridges and does not misfire, is silent, does not need to be cleaned, an ordinary nail can act as a cartridge for this electromagnetic rail gun, and the Gauss rifle works on the principle of alternating magnetic field, accelerating objects to mind-blowing speeds.

Since, unlike other weapons, you can find and buy electromagnetic gun Gauss is not allowed, here we will talk in detail about its circuit, operating principle and how to make this Gauss rail rifle at home with your own hands.

Attention! Having assembled an electromagnetic rifle or pistol with your own hands, do not forget to register your rail gun with the police and obtain permission to carry it or store it at home for self-defense, because like other weapons, the Gauss gun poses a mortal danger to you and the people around you, and Illegal possession of it is punishable by the criminal code!

How to make a homemade Gauss gun

To analyze in detail the principle of operation of a homemade Gauss rifle, let's first try to make a prototype of an electromagnetic rail gun from an ordinary ruler (a logarithmic one is best, so that by removing the middle from it, we get a groove for balls), 4 identical powerful magnets, a knife, adhesive tape and 9 metal balls with a diameter not exceeding the height of the magnets. Assembling a prototype rifle (let's call it a Gauss pistol) is as easy as shelling pears, even at home and with your own hands.

Tape the magnets to the ruler at equal distances from each other in the middle of the groove, making sure that the outer magnets are not too close to the ends of the ruler and charge 2 balls on one side of each magnet. To shoot, load the ball into the groove at the edge of the ruler on the side where there are no balls near the magnet and release. The magnetic field will attract it to the magnet, the ball will impart its energy to another ball through it, and due to the influence of this energy on it and, in addition, another magnetic field created by the next magnet in the circuit, it will accelerate it even faster, about 2 times.

OK it's all over Now! The prototype of a homemade Gauss gun was made at home with your own hands and, according to the principle of operation of the gun, is no different from the original, the Gauss rifle, we will now tell you how to assemble the diagram of which at home yourself.

How to make a Gauss gun

You can't assemble a Gauss rifle with just magnets and a ruler. Where to find starting materials for free? Most likely, you will have to at least spend money on several 400-450 Volt capacitors, the total capacity of which would be in the range of 1000-2000 mF, a copper wire with insulation with a diameter of 1 mm, a compartment for Krona type batteries and a pair of one and a half volt batteries, a trigger mechanism for your homemade Gauss rifle at home in the form of a button and a toggle switch, about 5 disposable cameras that have a flash, a couple of straws from some McDuck, in which you can also eat for free, a regular relay from a Zhiguli car on 4 contacts and some kind of housing for a Gauss gun in the form of a toy pistol, machine gun, etc., on which it will depend appearance your homemade electromagnetic Gauss rail gun, which can be made according to the following scheme:

The principle of Gauss weapons is also built on the electromagnetic properties of a gun; a dielectric barrel along with an iron charge is located inside an inductive coil, and when electricity is supplied to the solenoid, the resulting magnetic field gives the projectile considerable acceleration.

If you haven’t guessed yet, we need disposable cameras for the sake of a capacitor charging device, because we don’t want to make a disposable Gauss rifle? However, when disassembling a disposable camera, be extremely careful, never touch parts of the electrical circuit and close the capacitor output as quickly as possible using a screwdriver with a dielectric handle. Clean the charger from the battery clips, capacitor and solder a bridge to it to the contacts of the button to charge the future Gauss electromagnetic rail gun. Follow the above method with the remaining disposable cameras.

In order for the acceleration of a rail gun to be maximum, by the time the projectile reaches the solenoid (an inductive coil that does not have a core), the magnetic field must also be maximum, dropping sharply when the projectile is close to the solenoid, for this it is necessary to coordinate the characteristics of the capacitors, the projectile and coils of the future homemade Gauss rifle.

To make a solenoid for a Gauss gun, assemble together 4 cm of straw, two washers big size from plastic or cardboard, assembling a bobbin using a nut and screw. Wind the copper wire, carefully making sure that the wire is not bent anywhere and that the insulation is not inadvertently damaged; before winding the next layer, and there should be ten of them in total, fill the previous one with superglue. Disassemble the structure and insert a long straw into the solenoid, which will become the barrel of an electromagnetic Gauss rail rifle with your own hands at home. You can check the functionality of the resulting part using a regular 9V battery and a paper clip.

Having assembled a Gauss gun according to the circuit, before firing, monitor the LEDs to determine the moment when the voltage of the capacitors has increased to the 330V we need, usually this takes up to a minute, but if you connect several 3V batteries in parallel to charging the capacitors so that each 3V compartment is connected in parallel all charges so that the charging boards do not burn out, then the reloading time for a homemade Gauss rifle assembled at home can be significantly reduced.

To ensure the safety of a ready-made Gauss electromagnetic rail gun made with your own hands at home as trigger mechanism use a relay so as not to contact the button that discharges the capacitors directly. A high-voltage circuit can only be assembled with a wire with a diameter of at least 1 mm, and the capacitors must be additionally discharged, arranging short circuit, so that the Gauss cannon can be safely stored at home after firing.

To fire from a homemade Gauss rifle, turn on the power, wait for a signal from the LEDs, load the projectile so that it is slightly behind the solenoid, turn off the power and shoot. An electromagnetic rail weapon made using this method is amazing in its power and should under no circumstances be aimed at living people.

If you don’t understand anything about this, then it would be better to start by studying

Possess a weapon that, even in computer games ah can only be found in a mad scientist's laboratory or near a time portal to the future - that's cool. Watching how people indifferent to technology involuntarily fix their eyes on the device, and avid gamers hastily pick up their jaw from the floor - for this it is worth spending a day assembling a Gauss cannon.

As usual, we decided to start with simplest design- single-coil induction gun. Experiments with multi-stage projectile acceleration were left to experienced electronics engineers capable of building complex system switching on powerful thyristors and fine-tune the moments of sequential switching of the coils. Instead, we focused on the ability to create a dish using widely available ingredients. So, to build a Gauss cannon, first of all you have to go shopping. In a radio store you need to buy several capacitors with a voltage of 350-400 V and a total capacity of 1000-2000 microfarads, enameled copper wire with a diameter of 0.8 mm, battery compartments for the Krona and two 1.5-volt type C batteries, a toggle switch and a button. In photographic goods, let's take five Kodak disposable cameras, in auto parts - a simple four-pin relay from a Zhiguli, in "products" - a pack of cocktail straws, and in "toys" - a plastic pistol, machine gun, shotgun, shotgun or any other gun that you want to turn it into a weapon of the future.


Let's go crazy

The main power element of our gun is the inductor. With its manufacture it is worth starting assembling the weapon. Take a piece of straw 30 mm long and two large washers (plastic or cardboard), assemble them into a bobbin using a screw and nut. Start winding the enameled wire onto it carefully, turn by turn (with a large wire diameter this is quite simple). Be careful not to allow sharp bends in the wire or damage the insulation. Having finished the first layer, fill it with superglue and begin winding the next one. Do this with each layer. In total you need to wind 12 layers. Then you can disassemble the reel, remove the washers and put the reel on a long straw, which will serve as a barrel. One end of the straw should be plugged. It's easy to test the finished coil by connecting it to a 9-volt battery: if it holds a paper clip, you've succeeded. You can insert a straw into the coil and test it as a solenoid: it should actively draw a piece of paper clip into itself, and when connected pulsed, even throw it out of the barrel by 20-30 cm.


Once you get comfortable with a simple single-coil circuit, you can test your strength in building a multi-stage gun - after all, this is what a real Gauss cannon should be like. Thyristors (powerful controlled diodes) are ideal as a switching element for low-voltage circuits (hundreds of volts), and controlled spark gaps are ideal for high-voltage circuits (thousands of volts). The signal to the control electrodes of the thyristors or spark gaps will be sent by the projectile itself, flying past photocells installed in the barrel between the coils. The moment when each coil turns off will depend entirely on the capacitor supplying it. Be careful: excessively increasing the capacitance of the capacitor for a given coil impedance can lead to an increase in pulse duration. In turn, this can lead to the fact that after the projectile passes the center of the solenoid, the coil will remain on and slow down the movement of the projectile. An oscilloscope will help you track and optimize the moments of turning on and off each coil in detail, as well as measure the speed of the projectile.

Dissecting values

A battery of capacitors is ideally suited for generating a powerful electrical pulse (in this opinion, we agree with the creators of the most powerful laboratory railguns). Capacitors are good not only for their high energy capacity, but also for their ability to release all the energy within a very short time, before the projectile reaches the center of the coil. However, capacitors need to be charged somehow. Fortunately, we need Charger found in any camera: a capacitor is used there to form a high-voltage pulse for the ignition electrode of the flash. Disposable cameras are best for us, because the capacitor and “charging” are the only electrical components, which they contain, which means that getting the charging circuit out of them is as easy as shelling pears.


The famous railgun from the Quake series takes first place in our ranking by a wide margin. For many years, masterful use of the “rail” has distinguished advanced players: the weapon requires filigree shooting accuracy, but if it hits, the high-speed projectile literally tears the enemy to pieces.

Disassembling a disposable camera is a step where you need to start being careful. When opening the case, try not to touch the elements electrical circuit: The capacitor can retain charge for a long time. Having gained access to the capacitor, first short-circuit its terminals with a screwdriver with a dielectric handle. Only after this can you touch the board without fear of getting an electric shock. Remove the battery brackets from the charging circuit, unsolder the capacitor, solder a jumper to the contacts of the charging button - we will no longer need it. Prepare at least five charging boards in this manner. Pay attention to the location of the conductive tracks on the board: you can connect to the same circuit elements in different places.


The sniper gun from the exclusion zone receives the second prize for realism: the electromagnetic accelerator, made on the basis of the LR-300 rifle, sparkles with numerous coils, characteristically hums when charging capacitors and kills the enemy at enormous distances. The power source is the Flash artifact.

Setting priorities

Selection of capacitor capacity is a matter of compromise between shot energy and gun charging time. We settled on four 470 microfarad (400 V) capacitors connected in parallel. Before each shot, we wait for about a minute for a signal from the LEDs on the charging circuits, indicating that the voltage in the capacitors has reached the required 330 V. The charging process can be accelerated by connecting several 3-volt battery compartments in parallel to the charging circuits. However, it is worth keeping in mind that powerful “C” batteries have excessive current for weak camera circuits. To prevent the transistors on the boards from burning out, each 3-volt assembly must have 3-5 charging circuits connected in parallel. On our gun, only one battery compartment is connected to the “chargers”. All others serve as spare stores.


Location of contacts on the charging circuit of a Kodak disposable camera. Pay attention to the location of the conductive tracks: each wire of the circuit can be soldered to the board in several convenient places.

Defining safety zones

We would not advise anyone to hold a button under their finger that discharges a battery of 400-volt capacitors. To control the descent, it is better to install a relay. Its control circuit is connected to a 9-volt battery through the shutter button, and the control circuit is connected to the circuit between the coil and the capacitors. It will help to assemble the gun correctly circuit diagram. When assembling a high-voltage circuit, use a wire with a cross-section of at least a millimeter; any wire will be suitable for the charging and control circuits. thin wires. When experimenting with the circuit, remember: capacitors may have residual charge. Discharge by short circuit before touching them.


In one of the most popular strategy games, the foot soldiers of the Global Security Council (GDI) are equipped with powerful anti-tank railguns. In addition, railguns are also installed on GDI tanks as an upgrade. In terms of danger, such a tank is about the same as the Star Destroyer in Star Wars.

Let's sum it up

The shooting process looks like this: turn on the power switch; wait for the LEDs to glow brightly; lower the projectile into the barrel so that it is slightly behind the coil; turn off the power so that when firing, the batteries do not take energy from themselves; take aim and press the shutter button. The result largely depends on the mass of the projectile. Using a short nail with a bitten off head, we managed to shoot through a can of energy drink, which exploded and flooded half the editorial office. Then the gun, cleaned of sticky soda, launched a nail into the wall from a distance of fifty meters. And our weapon strikes the hearts of fans of science fiction and computer games without any shells.


Ogame is a multiplayer space strategy in which the player will feel like an emperor of planetary systems and wage intergalactic wars with the same living opponents. Ogame has been translated into 16 languages, including Russian. The Gauss Cannon is one of the most powerful defensive weapons in the game.

Almost every resident of the CIS has at least heard about such a wonderful game as “Stalker”, because it tells us about an alternative reality in which, after the explosion at the Chernobyl nuclear power plant, a rupture of the noosphere occurred, from which everyone who was there was irrevocably changed, both physically, as well as mentally. Mutants, artifacts appeared, as well as many research centers studying the anomalous nature of the region. One of their achievements was the Gauss gun. In this article we will tell you in detail where to find this gun in different fashions, parts of “Stalker”, as well as a little history.

History of creation

First this type rifle appeared in the first part of “Stalker”, which was called “Shadow of Chernobyl”. At the penultimate location “Pripyat” the player was met by multiple enemy forces, they were everywhere, even on the roofs of abandoned houses, from which they fired at us with Gauss. The rifle itself is incredibly rare, and if you didn’t kill the Monolith correctly, then we can safely say that you won’t touch it again in the game. There is also a chance that the corpse of this fighter will fall, but there will be no cartridges for the rifle at all. All this is due to the fact that the development of the first part was carried out in incredible haste, many types of weapons were cut out, not to mention locations, cars and much more.

If we talk about mentions of this rifle, then in the “Dark Valley” location, right opposite the bandits’ base, we could save a stalker from a bloodsucker, for which he thanks us with the information, they say, on a pig farm they sell a Gauss gun for only 800 rubles. We go there, give the stalkers 800 rubles, which at the very beginning of the game can change a lot, but in return they give us nothing, and even more: we are kicked out of the territory of the pig farm, because... They don’t have any Gauss rifle, and this money will go to charity. After this, you can calmly kill them, and the “Ghoul” stalker will drop a special “Viper” silent rifle.

This all happened in the first part, but now in the second, whose name is “Clear Sky”, you can quite easily find this rifle. The right to purchase it is given to players whose actions are impeccable (statistics can be viewed in the PDA), after which every merchant will happily sell you Gauss and the first generation exoskeleton.

“Call of Pripyat” tried to be as similar as possible to the first part, which, in fact, happened, because in this part the rifle is taken again from the roof and again from the corpse of a fallen “Monolith” soldier. After picking it up, a special quest is activated, which we will talk about a little later.

Real analogues

Fortunately, and maybe even unfortunately, such weapons exist in modern world, although it is quite stationary. In the Stalker series of games, we were given to understand that the Gauss cannon is mobile and so deadly only because of its autonomous power source. The power of the game and real guns are slightly different. But they're both still incredibly deadly.

IN real life the name of this gun is “Railgun”, from the name alone you can understand that the barrel of this gun contains two long magnets, and at the very beginning a projectile that is not a dielectric, because will not respond to a colossal magnetic field. A magnetic field of enormous power is created thanks to high voltage, capable of providing 19 thousand homes, and this is a small city.

During the flight, the projectile collides with an obstacle, and due to the incredible high speed(more than 1.5 kilometers per second) it does not require an explosive element, because one kinetic energy enough not only for an incredible blow, but also to pierce through almost any obstacle. They plan to equip US Navy warships with the “Railgun” by about 2020, but now full-scale development of a power source capable of charging such a deadly gun is underway. We talked about the real sample, now we need to find out where to find the Gauss gun. By the way, you can get a gun by cheating, but we do not recommend doing this, because... this disrupts the gameplay, unlike custom modifications in which this rifle is fully implemented. There are many similar mods, and finding them is not difficult.

Where can I find the Gauss cannon in Call of Pripyat?

To activate this incredibly interesting quest, you will first need to get to “Pripyat”, but before that, assemble a team of “Givi”, the former “Monolith” and the alcoholic “Dolgovets”, who sits in a tower near the “Yanov” station. Only each of them will need your help. To get one out of debt, for another to find the meaning of life, and for the third to have a good drink. All the quests are incredibly interesting, so we recommend going through them, after which you can invite them with you on a hike through the abandoned tunnels near Pripyat. Upon arrival, you will be greeted by a detachment of military men, thanks to whom you can get this gun.

After negotiations with the military, you are sent on a mission where you need to free old hospital from "Monoliths". After destroying half of the enemies, there will be a message that a sniper with an unusual rifle has appeared on the roof. Kill the sniper, take the Gauss cannon and go to the general for dry cleaning. After some deliberation, you are sent to Cardan’s ship.

Cardan says that in Soviet times he was a scientist and developed this gun, and to repair it after the scrape in Pripyat we will need to go down to the laboratory near the transformers. After the dialogue, he kindly gives us the key card, and we go down into the dungeon for the drawings of the Gauss rifle. We give all the documents to Cardan, and he gives us the repaired rifle.

Where can you find the Gauss gun in Shadows of Chernobyl?

In this part, everything is much more complicated, because the chance to get a gun will be almost at the penultimate location - in Pripyat. In front of the abandoned stadium, "Monoliths" from Gauss will shoot at you. Every hit on you will be critical, and if it hits you in the head, it will be fatal. It is categorically not recommended to shoot them in the forehead, because this will cause the gun to fall onto the roof, which cannot be climbed in any way, so you will need to run from cover to cover, and then shoot in the side of this fighter. The fighter and his rifle fall to the ground. If you are very lucky, you will find ammo in the corpse's backpack. By the way, it is almost impossible to find cartridges, only from very rare caches. You won't find them at merchants.

Where to find a cannon in Narodnaya Solyanka

Many people ask the question of where to find the Gauss gun of stalker Prokopenko, because the developers from AMK made this quest very, very difficult. To receive it, you will first need to get a pass to the debt territory, then go to Petrenko and talk to him on different topics, after which she will tell us that a Gauss pistol has disappeared somewhere in the Dark Valley. We run to the pig farm, which was mentioned above, go to the barrel on a support, which is located directly opposite the stone fence, and under the barrel there will be a pistol lying unattended. You can understand this yourself if you open the PDA and look at the screenshot in the instructions for the quest.

Is it possible to improve the Gauss rifle?

As already mentioned, all parts of “Stalker” were created in incredible haste, which is why not all the possibilities were realized, including weapon modifications. Yes, in “Call of Pripyat” and “Clear Sky” there is a mechanism for improving weapons, but not all units. This problem happy to solve custom modifications. In “People's Solyanka” 2017, you can buy a special case with tools from any merchant, or go to the Bar, where two professors will improve the characteristics of not only the Gauss gun, but also other rare weapons.

What ammunition is needed?

In "Stalker. Call of Pripyat" the Gauss gun has 2 types of ammunition: high-quality, i.e. industrial, handicraft. The two types of ammunition for the same rifle differ only in penetration power, as well as in price, which makes players pay attention to the second option. Factory ones can be purchased from stalkers for about 2000 rubles, if you are in good relations with the seller. Artisanal can create Cardan for us after completing the quest we talked about above. For a fee in the form of vodka, he will create homemade ammunition for us.

Finally

We hope that after reading this article you understand what a Gauss gun is. This weapon is the most powerful, so the demand for it is incredibly high. If for some reason you were unable to get a Gauss rifle, then you can adjust the game configuration, after which it will be sold at the desired merchant.

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Quite a powerful model of the famous Gauss cannon, which you can make with your own hands from available materials. This homemade Gauss gun is very easy to make and has lightweight design, all the parts used will be available to every DIY enthusiast and radio amateur. Using the coil calculation program, you can get maximum power.

So, to make a Gauss Cannon we need:

  1. A piece of plywood.
  2. Sheet plastic.
  3. Plastic tube for muzzle ∅5 mm.
  4. Copper wire for coil ∅0.8 mm.
  5. Large capacity electrolytic capacitors
  6. Start button
  7. Thyristor 70TPS12
  8. Batteries 4X1.5V
  9. Incandescent lamp and socket for it 40W
  10. Diode 1N4007

Assembling the housing for the Gauss gun circuit

The body shape can be any, it is not necessary to adhere to the presented scheme. To give the body an aesthetic appearance, you can paint it with spray paint.

Installing parts into the housing for the Gauss Cannon

To begin with, we attach the capacitors, in this case they were attached to plastic ties, but you can come up with another fastening.

Then install the socket for the incandescent lamp on outside housings. Don't forget to connect two wires to it for power.

Then we place the battery compartment inside the case and fix it, for example, with wood screws or in another way.

Winding a Coil for a Gauss Gun

To calculate a Gaussian coil, you can use the FEMM program; you can download the FEMM program from this link https://code.google.com/archive/p/femm-coilgun

Using the program is very easy, you need to enter the necessary parameters in the template, load them into the program and at the output we get all the characteristics of the coil and future gun in general, up to the speed of the projectile.

So let's start winding! First you need to take the prepared tube and wrap paper on it using PVA glue so that the outer diameter of the tube is 6 mm.

Then we drill holes in the center of the segments and place them on the tube. Using hot glue we fix them. The distance between the walls should be 25 mm.

We place the coil on the barrel and proceed to the next stage...

Scheme of Gauss Cannon. Assembly

We assemble the circuit inside the case using hinged mounting.

Then we install the button on the body, drill two holes and thread the wires for the coil there.

To simplify use, you can make a stand for the gun. In this case it was made from wooden block. IN this option The carriage left gaps along the edges of the barrel, this is necessary in order to adjust the coil, moving the coil, you can achieve the greatest power.

The cannon shells are made from a metal nail. The segments are made 24 mm long and 4 mm in diameter. Shell blanks need to be sharpened.

Hello. Today we will build a Gauss cannon at home using parts that can easily be found in local stores. Using capacitors, a switch and a few other parts, we will create a launcher that can use electromagnetism to launch small nails up to a distance of about 3 meters. Let's get started!

Step 1: Watch the video

Watch the video first. You will study the project and see the gun in action. Read on to explore more detailed instructions assembly of the Gauss Gun device.

Step 2: Gathering the necessary materials

For the project you will need:

  1. 8 large capacitors. I used 3,300uF 40V. The key point The point here is that the lower the voltage, the less danger, so look for options in the region of 30 - 50 Volts. As for capacity, the more the better.
  2. One high current circuit breaker
  3. One coil of 20 turns (I twisted mine from 18awg wire)
  4. Copper sheet and/or thick copper wire

Step 3: Glue the capacitors together

Take the capacitors and glue them together so that the positive terminals are closer to the center of the glue. First glue them into 4 groups of 2 pieces. Then glue two groups together, resulting in 2 groups of 4 capacitors. Then place one group on top of the other.

Step 4: Assembling a group of capacitors

The photo shows what the final design should look like.

Now take the positive terminals and connect them to each other and then solder them to the copper pad. The cover can be a thick copper wire or sheet.

Step 5: Solder the copper pads

Use directed heat if necessary (slight industrial dryer), heat the copper strips and solder the capacitor terminals to them.

The photo shows my group of capacitors after completing this step.

Step 6: Solder the Negative Terminals of the Capacitors

Take another thick conductor, I used an insulated copper lead with a large cross-section, removing it in in the right places isolation.

Bend the wire so that it covers the entire distance of our group of capacitors as efficiently as possible.

Solder it in the right places.

Step 7: Prepare the projectile

Next you need to prepare a suitable projectile for the reel. I wound my reel around the bobbin. I used a small straw as a muzzle. Therefore, my projectile must fit into the straw. I took the nail and cut it to about 3cm long, leaving the sharp part.

Step 8: Find a suitable switch

I then needed to find a way to dump the charge from the capacitors onto the coil. Most people use rectifiers (SCRs) for such needs. I decided to take a simpler approach and found a switch that worked when high strength current

There are three current ratings on the switch: 14.2A, 15A, and 500A. My calculations showed a maximum force of about 40A at a peak lasting about a millisecond, so it should have worked.

THE NOTE. Do not use my switching method if your capacitors are larger. I pushed my luck and it all worked out fine, but you don't want a breaker to blow because you ran 300A through a breaker rated for 1A.

Step 9: Winding the Reel

We are almost finished assembling the electromagnetic gun. Time to wind the reel.

I tried three different coils and found that about 20 turns insulated wire 16 or 18 awg standards work best. I used an old bobbin, wrapped some wire around it and threaded a plastic straw through it, sealing one end of the straw with hot glue.

Step 10: Assembling the device according to the diagram


Now that you have all the pieces ready, put them together. If you have any problems, follow the diagram.

Step 11: Fire Safety


Congratulations! We made the Grasse cannon with our own hands. Use a charger to charge your capacitors to near maximum voltage. I charged my 40V setup to 38V.

Load the projectile into the tube and press the button. The current will flow to the coil and it will shoot a nail.

BE CAREFUL! Even considering that this is a low-current project and that it will not kill you, such current can still harm your health. The second photo shows what happens if you accidentally connect plus and minus.