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

Comments

[Nuclear Radiator]

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

[ARJOON]

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

[scci]

How fast cand far can it shoot?

[ARJOON]

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

[abhishek shinde]

nice work !

[leekg]

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

[ARJOON]

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

[thetkdchamp01]

(removed by author or community request)

[ARJOON]

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

[jpillai]

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

[ARJOON]

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

[lstaničić]

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

[ARJOON]

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

[lstaničić]

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.

[ARJOON]

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.

[lstaničić]

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?

[ARJOON]

yes, but transformer should be of higher voltage

[Doyletheking]

Sweet

[padmanabhapsimha]

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.

[padmanabhapsimha]

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

[ARJOON]

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

[padmanabhapsimha]

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.

[ARJOON]

you are right

[jensenr30]

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

[jam BD]

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

[ARJOON]

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