Hi guys. This here is my design of a coilgun which is a project I was preparing to make
for a long time and I finally made a first version. Before we start, I have to warn you
that this is a quite dangerous project for 2 reasons. First, well it fires projectiles
at high speed. And second, it works with very high voltage, around 500V so please be careful
if you want to make the same project. Use proper tools, stay insulated and never touch
the exposed wires while the board is powered on. Also make sure that you fully discharge
the huge capacitors each time, because these could store a huge amount of charge. Ok so
my design is a bit special and you will see that it is made out of separated PCB for each
stage. So if you want more power and more speed, you can just add another stage. Each
segment PCB works by its own, having the coil, the capacitor, the power control and the bullet
detector so it is very easy to add more stages. So, what do you think? Would this be able
to fire through a cardboard box? That sound quite easy, right?. But what about a 4mm plywood
sheet? What about some plexiglass? What about some 3mm MDF which is a strong material? Well,
stick till the end of the video to find out and by the way, below in the description you
can find all that you need to make this same project, such as my schematics, my PCB designs,
the part list and so on. So, safety glasses on, and let’s get started.
What’s up my friends, welcome back. I had these big capacitors in my workshop for more
than two years and that’s when I’ve decided to make a coil gun. But since this is a complex
and also dangerous project, every time I had free time, I was making tests for the MOSFET
control, or maybe IGBTs or Thyristors, the coil configuration and amount of windings,
to see if I should go with high voltage or low voltage control, the bullet detection
circuit and so on and I finally make these PCBs. As you can see, my design is a bit special
and is made out of multiple PCBs. We have this first main board and the rest are merging
together to create the gun. The main PCB must be the first stage because it will have the
supply connection and the firing push button. And then, all the rest of the PCBs are exactly
the same but the more stages we put, more speed will the projectile get. In this way,
you can make your coil gun have any amount of stages you want just by adding more PCBs
with the same circuit. If you want to make the same project, you can get my GERBER files
for both PCBs from below. Then you can go to PCBWAY and order the same boards. Click
the quote now button and add the settings. In my case I wanted them to be black and I’ve
ordered 10 PCBs. Save to cart and upload the GERBER files you have downloaded from my website.
Make the payment and in around 7 days I receive the boards to Spain and they look amazing.
Remember you need two files, for the main board and other files for the segment PCB.
Each of this coil gun segment can work by its own since it has the detection and power
control circuit which is not affected by the rest of the coil gun and we will see how it
works in a moment. So as you can see here on my table, this is all we need for one segment
which is not that much. But since I want to have multiple stages, this project needs a
lot of components so before we start assembling the PCBs, generating high voltage, making
tests and so on, let me first explain to you how a basic coil gun works and in which ways
we could implement it. A coil gun is based, well, on a coil, obviously. When we apply
current to this coil, a magnetic field will be created around it. The more amount of loops
we have and the bigger is this current value, the stronger will the magnetic field be so
for that we have to take in account the wire thickness, its resistance, the amount of loops
the coil has and the voltage we apply to that coil. This magnetic field will attract a metal
projectile that we have on one side. The projectile must be ferromagnetic otherwise the magnetic
field won’t attract it. But here appears the first problem. The created magnetic field
is equal on both sides of the coil, on the left and on the right. So the projectile is
attracted from the left side but once it passes the middle of the coil, it will be attracted
backwards by the right side magnetic field. So, what the projectile will do is to oscillate
till it stops exactly in the middle of the coil. Here I’m making some test and I apply
around 60 volts to my coil and record it in slow motion. As you can see, the projectile
is attracted but it will oscillate inside and get stuck in the middle. Only if I briefly
touch the coil it will fire the projectile on the other side. And why is that? Well,
what we want is to cut off the magnetic field, exactly when the projectile is getting passed
the middle of the coil. In that way it accelerates, we stop the magnetic field and the projectile
will keep going forward. Instead of just one coil we can add multiple coils. So the bullet
will be accelerated by the first stage, and when it gets out the first coil, we stop the
first one and activate the second magnetic field and it will accelerate the bullet even
more. Then we do the same with the third stage and so on, and as you can see, the more stages
we have the faster the bullet can go. Each of these small PCBs represents one stage and
each will have its own coil, its own projectile detector and the power control. So by placing
theme in series, we can get any amount of stages for my coil gun. But how can we know
when the bullet is passing the middle of the coil? Well, we use phototransistors like this
one here. On one side I have an infrared light and in front of it I have the phototransistor
which gets activate when touched by infrared light. Here I have that setup on a breadboard
supplied at 5V and the LED and detector are face to face. So, obviously, when I place
something in between, as you can see on the oscilloscope, the output is deactivated and
when I remove the blocking object, the output is back again. So what we can do is to place
this setup along the coil gun tube just at the output of the coil. Like this we can detect
when the projectile will exit the coil, because it will block the light from the infrared
LED and deactivate the phototransistors. So, we place this LED and the phototransistors
at the exit of the coil. Since the projectile is pretty much a bit longer than the coil,
it will exit on the other side while the left end is still before the middle of the coil.
At this point the phototransistors gets triggered because the light from the LED can’t reach
it anymore because the bullet is blocking the light. We can get this signal from the
detector and apply it to a control circuit that controls a Thyristor. This Thyristor
is connected to the coil, so we can turn on and off the power, and with that on and off
the magnetic field. When we detect the bullet, we cut off the power so the projectile can
continue on the other side. And that’s how is done. The circuit I have for the coil gun
segment is something like this. I have this Thyristor connected to the coil. Its gate
is connected to this BJT transistor which is controlled by the infrared sensor output.
The circuit is supplied at 450V DC and we will see how to get that voltage in a moment.
So, if you want to make such project, please be careful working with high voltages since
it could hurt you really bad or even worse. Use proper tools, stay insulated and never
touch the high voltage parts. To get 450V we can use this kind of inverter modules.
There are all kind and sizes of such modules and in my case, I will use this one which
is a bit bigger. We need it to be bigger since I want to have multiple stages so we need
more power in order to fill all the capacitors. This module can be supplied with 12V and it
will give around 300V AC but it gets rectified with this full bridge rectifier here so we
can get 400V DC, more or less. To store all the charge and then release it at once, we
need to use these huge high voltage capacitors. Each stage will have one. Capacitors can charge
to high voltages very fast and discharge almost instantly without damaging themselves so is
a way better solution than using batteries. That’s why we get power from batteries first,
we increase the voltage and we store the charge inside the capacitors. And then we release
it all at once into the coil, creating a powerful magnetic field. Ok guys so this is pretty
much all that we need to make such a project. So, we need PCBs, the high voltage capacitors,
we also need Thyristors. We need some infrared LEDs and some phototransistors. We also need
some BJT transistors. The rest are some resistors and some LEDs. We also need the copper coils.
To make these you can download from below my 3D design. Remove the supports and you
will be left with this support. Then you can add around 150 loops using thick copper wire
that could withstand enough current. Once you have all the loops, you can add some KEPTON
tape on top so the coil will stay that way. Or if you think that’s too much work, you
can find these coils to buy on the internet. We also need some powerful diodes and some
push buttons to fire the gun. On the other side we need the high voltage module and maybe
a 3S battery or even better a battery socket like this one. As projectiles I will use some
6 to 7mm metal rods that you could cut to around 2cm and maybe smooth the edges. As
the gun barrel, I will use an 8 mm metal tube. It would be better to use a plastic tube so
there would be less magnetic attraction and less friction with the bullet. You have to
make holes on this tube from side to side. The space between these holes is the same
as the space on the segment PCB. Through these holes we add the infrared LED and the sensor
so we can detect when the bullet is passing through. Ok guys so let’s assemble this
coil gun. First part is to assemble the main segment. The circuit for this part is a bit
different and is this schematic here. This PCB has two stages and we have the same power
control part as before, but the Thyristor is activated with a push button. This PCB
also has the input of 450V and 12V from the battery pack. As you can see, the PCBs have
exposed copper so we can merge them together with solder. So we put them like this and
we solder the connection. We have 3 connections on the tops ide and 1 on the back. I place
the PCB flat on the table and join this part together with the next segment using solder
and some solid wire. First segment is in place. I add 2 more segments for now and we will
see if we add more later. Now I have the PCB ready for the components. First, we add the
huge capacitor and make sure it is on the bottom part of the PCB since on top we will
have the coils. Follow the indications on the PCB in order to know where is positive
and negative. Then I solder the diodes. You will see that one diode can’t go through
since we have the capacitor below so we have to solder it like this. Then I add all the
resistors for the first and second stage. I add the small BJT transistor for the second
stage. Then I add the LEDs but I don’t solder the infrared LED and the phototransistor yet,
we do that after we add the coil. Next step is to add the Thyristors and they have the
pin connection labeled on the PCB so don’t put them backwards. So now we solder the coil,
so measure the wire length and clean out the enamel from the wire. Then you cut it to size
and solder the coil on its holes. Now we can measure the LED and phototransistor height
and solder them in place so they would be at the height of the coil tube. Also make
sure the infrared LED is in face to face with the phototransistor. I supply the board at
12V for a moment and as you can see, when I rotate the tube so the light can’t pass,
the red LED will turn on, indicating that the Thyristor is active. On these 3 pins I
solder this display module. This is a high voltage indicator and it will show us the
capacitor voltage. The first and the second stage are ready. I supply 12V to the PCB on
these pins. I also connect the high voltage transformer to the PCB, but I don’t supply
it yet. Then I add this push button as a trigger and we are ready to fire. I place a projectile
at the input of the tube. Now I connect the transformer to 12V and we can see on the small
display how the capacitors are charging up to almost 500V. Now I press the button.
That was a lot of power and with only 2 stages. It went through this cardboard box. Amazing.
Here is a second attempt. So the projectile is fired away so it works. Is time to add
the next stages. These connections on the PCB are not just for support. They also carry
450V to the next stages so make sure you don’t touch these pads while the gun is powered
on. This is the design of the PCB and you can see I’ve used thick enough tracks so
they could carry enough current without burning out. I solder the next stages as I did with
the first ones, the resistors, the Thyristors and the coils. Now I have 5 stages so we can
make another test. As you can see, if I rotate the tube, each of the red LED will turn on
since we have a pair of infrared LED and phototransistor for each hole. You can add some hot glue to
keep the LEDs in pace if you want. This gun needs a support but I’ll do that in a future
video, maybe a 3D printed support, that would be cool. I add another projectile. I put this
cardboard box in front of the gun. I connect power to the high voltage module and as you
can see, we charge up the capacitors up to around 500 volts. Now we fire.
Amazing, it passed through both sides of the cardboard box and I’ve got to say, it looks
pretty fast and also a bit dangerous. With 5 stages it is definitely faster, so imagine
when I get to 10 stages. Here is another test and again it passed through both sides of
the box. This time I will fire it at some plywood. And once again, amazon. It passed
through without any problems and this is 4mm plywood. This thing is very powerful so please
be careful. I can’t believe that it passed through this wood board so easy. Here I fire
it again. So much power. Here I’m firing it at some plexiglass. And once again, it
went through without problems. Final attempt was using a 3mm MDF board and guess what?
It passed through without problems and this is a quite strong material and it made such
a clean hole. Obviously, you can always add more stages and make it of 8, 9, 10 or even
more stages but I guess there will be a speed limit given by the speed of the component
commutation. Since you now have my design of separated stage, you can always solder
one more if you want. But even so, the bullet is very fast.
So guys, I hope that you like this project and have in mind this is just the first version.
In a future video I will make a case for the electronics, create a support for the gun
and give it a better look so stay tuned for that. If you like this video, consider giving
me a LIKE or comment below. Thanks again
and see you later guys.