Introduction: The Making of a Powerful Low Cost Coilgun Which Is Portable

In this intructable i will show you how i made my coilgun, I will first thank, steaveastrouk, re-design, lemonie, orksecurity and others who helped me with my questions.  I became quite interested with this coilguns from the videos that was featured on hacked gadgets and intructable. So i decided to make my own research to understand how it works. After months of research i decided to go to the practice session.



 Comment PLEASE

Step 1: Parts List

Well for the design use you imagination because the parts that i used for the casing will be very difficult to find because they are all from a dismantled photocopier. Therefore for the electronics you will need some parts that is easily available on market or by salvaging them

Parts

  400V Electrolytic Capacitors. The more capacitance the better it will be. say like over 2000uf or more (Free)
 1k 10W resistors X 2(Rs20)
 BD243C or 2N6121 transistor or equivalent X2(Rs64)
 A centre tapped transformer on primary. we will come to that later on(free)
 A power supply that is rectified mains, car battery, or other batteries, in my case i used 10 AA 1.2V NI-CD batteries (12v in series)  (free)
 Some very very high current switches or relays(free)
 Full Bridge Rectifier 400V 3A or more to be on the safe side X 2 (free, salvaged from TVs)
 A 100W bulb(Rs21)
 Lots of wires(Free)
 Aluminium Tubing(R75)
 Enamel coated wire, i used the 1.2mm wire that i got from a tv.(free),, u can also use bigger wire for more current
2 Medium Heat sinks

Step 2: Tools and Other Materials You Will Need

Tools
Hot melt glue gun
Soldering iron
Grinder
Jigsaw
Wire cutter and wire stripper
Pencil for marking...............
Drilling machine

 Useful goodies
.
Metal sheefs and a food container(plastic) of appropriate size for the casing and  insulation
Duct tape or electrical tape
Solder the 2mm one
Flux (optional if your solder is not of too good quality)
Wood 
Card Board
Battery holder

  Probably most important is a place to work. i conquered my mother's kitchen a few years ago and made it my workshop

Step 3: The Capacitor Bank

Find the maximum number of 400v electrolytic capacitors and connect them in parallel.

My capacitor bank ended up having a capacitance of 3475uF

 If you have 200v ones. connect them in series to give 400v and then in parallel to increase capacitance. 
Make sure you use very thick wires because it will be driving current up to 350A.
Beware of polarities, it can result in a big capacitor explosion

you can probably use different capacitor values, but it would mess with the pulse time and it would not work nearly as well as it would if you used, say, all 120 uF 330V capacitors. The different uF values mean that each capacitor will have a different discharge pulse time, so if you graphed the charge put out over time the line would be all squiggly and not like the ideal curve that a uniform bank would have. In a worst case scenario the coilgiun might end up shooting the projectile backward, but I don't think that that could actually happen. It probably will just shoot it really slow.

therefore i recommend you to use close values of capacitance of each capacitor. Mine is really messed up, but i am fairly satisfied with it's performance

Step 4: Making Your Coil

Well not much to say, Google is here

I used 2 wires for one coil to decrease the resistance.

 i attached a tube to my drill and started winding the coil

 Here are the two coils I've made

 Note that if you use high voltage of about 1KV or more you can use thinner wires with more turn,
if you use low voltage, thicker wire will be needed,

I= V/R

Step 5: Getting Started With the Capacitor Charger

I've seen a lot of people using disposable cameras capacitor charger for their gun. The disadvantages of it are

1. Takes about 5min to charge a big capacitor bank due to its small size, it won't carry current needed for good charging time
2. Combining chargers are good but will not last long and the cameras here in Mauritius are difficult to find
3. Disposable camera means one time use, therefore it will work for a limited amount of time

 I designed my own charger using combining mains supply and battery supply.

  feel free to modify the schematic if you want. It is a simple push pull driver.   

Charging time with my charger
3s from mains section
7s from battery secton
1s with 2 methods combined

Step 6: Packing Em in One

connect everything according to schematic below and you are done.

Relays allow more current to pass through them than regular push button switches, which normally weld together and then gets damaged.YOU can replace the relay with other devices like a thyristor or a big momentary switch.I found it best to use a relay because it switches very quickly and therefore last longer than other normal switches. most of the time the switches are damaged at the internal contact leads. 




i leave the casing development on you because parts are too uneven to find or make as is

 I will put other videos of it later on.

Total cost of Project: RS200(about $7)

Future developments
1. Make it more powerful using more capacitors,
2. Using a more efficient coil.
3. Try to use my 600A 1200V thyristor( this is so heavy
3. Reduce the charging time from mains to 1s
6. Place a laser pointer.
7. Design a semi automatic reload system.(  just like the one that was featured on hacked-gadgets



Comment PLEASE

Comments

author
Nick_Tesla (author)2012-09-11

How fast cand far can it shoot?

author
ARJOON (author)Nick_Tesla2012-09-12

hnnnm the measured speed depends on the mass and length of the projectile,

using sensors it is estimated to shoot about 150-250m/s on a full charge

and the effective range i don't know

author
robbertl1 (author)ARJOON2016-12-27

not even close, considered a very poor setup with way to less UF capacitance and a single stage. you may be glad to get 15m/s.
im not even talking about the eddy currents due to the alluminium tube.
my coilgun is still in design stage. with one coil running i achieve 20m/s with a 1500A thyristor and 4500uf charged to 450v.
so about 200 m/s with this setup is total b*llsh*t :)
big, powerfull and high end (multistage) coilguns manage to shoot 180m/s max!


author

hey I'm starting a new project making a dual stage coil gun would a 7 x 29mm soft iron bullet be too heavy for copper coils?

author
neil137 (author)2015-08-15

sorry im not sure how to ask questions on this site but it seems to be the place with people in the know.

i have several thousand dollars and a few months on my hands. i want a railgun. i dont mean the weak ones everyone else has. i want one that

rivals a rifle in speed and could do some seriious damage. could anyone point me to what parts to order from online?

or any tips to wiring and assembly? i have friends with cnc equipment and plenty of spare metal so it's not an issue, i just need some basic instructions

on how to get started and what speeds would be possible. if i have to incoporate a backpack too that's fine. i just want to put solid proof out there

that it's possible with todays tech. thank you.

author
BruhklenH (author)neil1372015-12-26

if you're asking this question you clearly don't have the technical know how to take on a project like that safely, start small and figure it out your self

author
babutxt (author)2014-12-04

Can this coilgun will be able to fire a 50gram projectile

author
Nuclear Radiator (author)2013-12-21

" A centre tapped transformer on primary. we will come to that later on(free)"
what does it mean?
explain about it to me please

author
ARJOON (author)Nuclear Radiator2014-09-15

found in old phone chargers. where the secondary is centre tapped. Here we use the secondary as the primary since we need to get from low voltage to high voltage.

sorry for late reply

Arjoon

author
Nuclear Radiator (author)2013-03-17

Will you please tell me that if there is any part which can replace CD battery or where to get CD battery.

author
ARJOON (author)Nuclear Radiator2013-03-19

it's a Ni-Cd battery (Nickel–cadmium battery). i used 10 in series 1.2V each resulting in 12V.

any other 12v power source is OK,

you can even use a computer powersupply if you want to sacrifice mobility
or use 2 6V SLA batteries/
you have the choice

author
Nuclear Radiator (author)ARJOON2013-12-21

then what should be amp of it?

author
ARJOON (author)Nuclear Radiator2013-12-21

5-10A

author
Nuclear Radiator (author)2013-12-21

and yes are u teeling that all that circuit near the coil can be replaced with a high voltage momentary switch??

author
ARJOON (author)Nuclear Radiator2013-12-21

high voltage and high current

author
Nuclear Radiator (author)2013-12-21

and yes can you show to how to make the coil and attaching it to the barrel?

author
Nuclear Radiator (author)2013-12-15

i know how to make fully automatic design. but still this is a HYPOTHETICAL design.i dunno if this works. if u want to know arjoon then mail me at: bhadani.kahan@yahoo.in

author
ARJOON (author)Nuclear Radiator2013-12-19

yes it works, i've made it and tested it

author
Nuclear Radiator (author)ARJOON2013-12-21

can you show me the design?

author
makdef (author)2013-09-12

I got impressed. not so elegant. but very clever this project. I am with a project like this. but Smaller. and I don't know, but the following tip maybe would help you: you can use more of one charger circuit. In my case, I'm using joulethief with secondary coil. so for me its's easier to have more of one circuit charger. and you must to use diode on the outs of each circuit to do not cause problems. and after the diode you can join them according with the polarity.

author
ARJOON (author)makdef2013-12-19

joule thief would take an eternity to charge the bank.

author
Nuclear Radiator (author)2013-08-26

Can you please tell me that how to make the coil and attach it to the circuit?
It would be a big help.

author
shock517 (author)2013-07-16

how are the batterys 220V in. or where is the power coming form you didnt explain how to connect the batteries to get that 220v?

author
ARJOON (author)shock5172013-07-28

don't get confused, this is a hybrid charger, using both batteries and mains current, the 12V in comes from the battery, and the 220V from the mains which is rectified to charge the capacitor bank.The inverter will achieve your desired voltage depending on the input voltage and the trasformer ration

author
abhishek shinde (author)2012-08-12

nice work !

author
leekg (author)2012-06-05

instead of using aluminium tubing, can I use like a plastic tubing?

author
ARJOON (author)leekg2012-06-06

yeah it's a must, i didn't make the coil around the aluminum tubing, all my coils are coiled around plastic tubing

author
ARJOON (author)2011-12-28

use the schematic. and the AC in is optional.and complete schematic is available on step 7

author
jpillai (author)2011-11-27

so basically it is an inverter with a stepup transformer and rectifier bridge try using voltage multiplier i endded up getting two blown caps hee and last step you told about using thick wire for low volt and thin for high isnt it wrong? it should be just the opposite in my opinion

author
ARJOON (author)jpillai2011-11-28

i don't thinks so. cross sectional area of a wire is inversely propotional to resistance. Therefore if you use thin wires the resistance will limit the power, so you will need a high voltage to carrry mo current. V=IR, P=IV

Xsectional area= (resistivity)(length)/resistance

author
lstaničić (author)2011-08-17

bad luck... i scavenged a perfect transformer and it has only four pins :/
does the transformer you have used have two coils on the one side and one on the other?
something like this? http://i51.tinypic.com/21kcyfa.jpg

author
ARJOON (author)lstaničić2011-08-18

use wind a very small toroid with 50turns on the secondary and 25+25 turns on the primary. connect the secondary of the toroid to the scavenged transformer. and use the centre tap as the primary of the whole thing

author
lstaničić (author)2011-08-15

why have you added a light bulb? isn't it much easier to add a resistor?
and if i use a 4:2 transformer instead of 4:3 will i need to change some of the other components as well?
sorry for all the questions. i know some basic electronics but i still don't quite understand this... finding a electronics shop that have 4:3 transformers in my country is like winning a lottery.

author
ARJOON (author)lstaničić2011-08-16

i used a bulb because it can withstand a lot of amps. i need a non-ohmic filament. it also indicates that the cap bank is fully charged when it dims out. Scavenge the transformer from old battery chargers, phone chargers, etc. or wind one yourself. no need to change other components.

author
lstaničić (author)2011-08-14

i have a few questions!
can i charge the bank with 3 or 4 AA's, or does it have to be 12v?
is this a 4:3 transformer?

author
ARJOON (author)lstaničić2011-08-14

yes, but transformer should be of higher voltage

author
padmanabhapsimha (author)2011-05-06

you have made a mistake in page 2
If you have 200v ones. connect them in parallel to give 400v and then in parallel to increase capacitance.
you actually need to connect 2 of 200v caps in order to double the voltage it can tolerate.
if you use different caps with different uF ratings they will act as a single capacitor with the total capacitance equal to the sum of the individual capacitances they will discharge as a single unit provided you charge them all to the same voltage. what you told about the backfiring and the really slow shot is totally wrong.

author
ARJOON (author)padmanabhapsimha2011-05-06

i can't formulate english phrases so well. go to wikipedia it will clear your mind

author
padmanabhapsimha (author)ARJOON2011-05-07

what do you mean? well if you are referring to the non uniform discharge it is wrong. the discharge is uniform. i am telling this because i have built a multistage coil gun with capacitors which have totally different capacitance values. (difference is about 2000 uF) the discharge curve over time is fine as long as the coil resistance and inductance are in the appropriate amount.

author
ARJOON (author)padmanabhapsimha2011-07-09

you are right

author

sorry in line two of my comment it is not in parallel to get 400 v but in series.

author
Doyletheking (author)2011-05-19

Sweet

author
jensenr30 (author)2011-04-30

Copiers and printers are the best for thin wires!!!

author
jam BD (author)2011-04-29

A few results from a firing will help make this ible better. But overall it was clear enough. Not bad :D

author
ARJOON (author)jam BD2011-04-29

yeah i have a few videos of it. it needs some editing

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