Coilgun Handgun

Step 7 Updates

News:
-The clip spring for my new rifle was completed and works properly, for the most part. 11/17/07
-Drilling through the back of the rounds proved a hard task and did not result in stabilizing the round completely, although it did mildly improve accuracy and velocity(Loss of mass). 11/16/07
-I just got a Velocity Chronograph to experiment more accurately with maximizing velocity.(Unfortunately it only works in sunlight and I'm not home to often during the day; Progress will be slow) 11/18/07
-Larger(C and D) Batteries provide the coil gun with a MUCH faster load time(Due to ampere increase) with the same amount of batteries. Used with 2 in series lined up with others that are 2 in series via Parallel) 11/18/07
-The general concept of more Charger Circuits for a curtain amount of Battery Power is flawed: I found that for every Battery Power there is a maximizing amount of circuit Boards to use but more batteries are always better unless you surpass the power rating of the charger circuits.( More research for different size Batteries is needed) 11/18/07
-Surprisingly Faster Charge Systems leading to large automatic coil guns possible. Due to Battery Breakthroughs. 11/19/07
-Solenoid that was bought doesn't contain a push back spring, new solenoid was found and will be installed shortly after arrival. (Another long wait for the main; which always seems to come right before work)
-Next Generation Coilgun will be a multistage rifle due to research into contact triggers(Goal is 75m/s, Possibly automatic which seems a simpler task than semi-auto if charge time is reduced significantly, I figure aim high)(HAMSEMLA I).11/21/07
-Final Research Design Before Rail gun research will be a multi barreled Mini gun type gun(Because it looks cool; O and it will allow the coils to cool between shots)11/24/07
-Research into the maximization of the coil of EMILA II has lead to an interesting discovery, the Kinetic energy of the projectile is maximized (As well as efficiency) when the projectile is the length of the Coil, while Velocity is maximized at about half the length of the coil. A worthy compromise between the two is a projectile at 3/4 the length of the coil. 11/24/07
-Placing a smaller straw at the ends of your projectile make them fly very straight, which although good, means that even flat headed rounds fly through two inch thick Styrofoam with ease. 11/24/07
- In general, for a certain coil in specific conditions, the center of a round must be a certain distance from the center of the coil no matter how long the round is. This means that for Larger Rounds, more placement inside the coil is needed, while smaller rounds require placement that may be outside the coil; eventually the small round is too far outside the coil, significantly decreasing its energy taken from the coil in terms of Kinetic Energy.11/24/07
- I experimented with a 12 layer coil(30mm Length) and some new capacitors(4 470uF 400 V). I used one 470uF 400 V capacitor and was able to more than match the velocity of the 1080uF 380V handgun. Efficiency of this is the best so far. 12/3/07
- I experimented later with the 12 layer coil and the new capacitors(4 470uF 400 V) I was able to align them to get 800 Volts at 470uF and was able to fire it around 8 times before the charger circuit's transistors started smoking then exploded(I used 8 charger circuits with 16 C Batteries lined up to get 12 Volts and a 900 Volts output( I also used a wall transformer and it basically exploded from the demands of the Capacitors before using the batteries). The result was an extremely powerful coil gun which when fired pierced 1mm thick steel plate as well as an entire tin can. See pictures below. 12/3/07
- I have not been able to make much progress on the newer hand gun and the charger meltdown is a huge set back. It will be a while till progress continues. 12/3/07
- Charger circuit tests show that you can use up to 6 C cell batteries in a 3V configuration with one charger circuit without burning up the transistor, I would recommend using just 2 per charger circuit, also using more charger circuits reduces resistance in the system and power capacity of the charging unit. 12/11/07
-Charger circuit tests show that you must use 3 charger circuit for just 2 D batteries at 3V in order to not burn up the transistors. I would recommend using at least 6 Chargers per 2 D batteries. 1/28/08
-Reverse Diode Across coil- Every professionally made coilgun uses a "protection" diode across the coil to prevent back emf. Research was done pertaining to this matter and a great deal of efficiency loss was examined. Several coils were tested and a average of about 1/4 of the velocity of the projectile was lost to the diodes prolonging the electromagnetic field. More research will be done but as of now great efficiency may be due to the lack of diode in my system. Also tests with a high rated diode connecting the coil to the capacitor which allows current flow one way, prevents a prolonged field, and prevents reverse voltage from back emf will be tested as well as other means to prevent back emf. 2/20/08
-Work on my new PA-III has been slow, but initial firings without maximization seem to put the gun as having great potential. The projectile ripped through a tin can and kept going until it suck in my drywall.
-PA-III Main support structure, Ammunition casing, and Power source construction has been completed. Next will be the autoloader and possibly a reduction in total stored energy as efficiency at high levels appears to dies of. A relationship between Increased voltage and Energy levels effect on efficiency will be mapped soon.
-I have moved and extensive work on my new workshop will be needed until research and other projects can be continued. 07/01/08
-Work on PA-III will be suspended until proper tools are accumulated again. 07/07/08
-The PA-III was redesigned and subsequently named PA-III-B, It is nearing completion and only requires painting as of now. Also previous research into camera circuits reveled that the number of camera circuits DOES NOT change the output of the circuits, but simply allows more power to flow through the them before failing. The ampere-hour rating , or capacity, however does directly relate to the output power, ie the more batteries you have in parallel (increasing capacity) the higher the output of the camera circuits until the point to which the chargers fail. Once time allows a graphical representation and report will be completed and posted as a link, time however is short so it may be a while. 11/11/08

Comments

[jalke116]

Good day!!!
I just want to know if What software are you using in making your digital schematics?

[Ben Mighall]

Do these things have recoil? And how loud are they?

[Dragon Shades X]

Recoil depends on the size and velocity of the projectile. Smaller ones have almost no recoil, but if you build one that shoots a bullet sized and weighted round and fired it as fast a bullet would normally go, it should have the same recoil as a normal firearm. Mine are pretty small, ~30m/s with 1g rounds, and I feel no recoil. And as for loudness, the only noise I have heard is the quiet click of the relay. So almost completely silent.

[mbrown9412]

yeah, they should theoretically be silent. except for the click and charging. the impact can be pretty loud though. or if there is a lot of recoil, that can make noise too. if noise IS made though, without much recoil then there is something wrong...

[coolin]

i made a coil gun much like yours but my coil gun needs a new cap bank after every shot. right after i shoot it electrisity arcs betwen the cap banks contacts and then the cap bank wont charge. please help!

[Dragon Shades X]

Can you give us more info? Number of capacitors? Coil diameter/length/width? Charger Circuits? Relay? Because without more info I can only say that you should check for crossed wires or solder that might be too close to other solder/wires that might cause the spark. The only other thing to do is trace/compare your circuit to the diagram that rwilsford provides. My coilgun fired fine, but sometimes it wouldn't charge again, but my issue was the the relay got stuck in the closed position, so it wouldn't charge again. You might try that as well, but it doesn't explain the capacitor spark. If you can give us more info we might be able to give you better ideas.

[unum]

I do not know much, but whenever I solder a connection I hot-glue over it to eliminate bridges. That might help if your capacitors are small enough.

[padmanabhapsimha]

your relay is getting stuck because the contacts are being welded together by the high current pulse. you should really consider replacing relays with solid state switches like SCR's or TRIAC's

[coolin]

I fond the problem. the pref bourd i used was slightly conductive and would short the caps

[mbrown9412]

what is a pref bourd?

[Dragon Shades X]

Excellent. Well, not excellent, but you found the problem and can fix it, and that is. I just used hot glue to stick it all to a large wooden board, but do whatever works for you.

[JOBGG]

my initial guess was that the sparkover fried your electrolytic capacitors because they are polar or something, and that the sparkover somehow occurred between the electrodes of the cap outside, but that the perfboard is where the sparkover occurred, well, then fix it that way.

@padmanabhapsimha
you can switch high voltages with scr's? I thought there's allways some kind of breakdown voltage for solid state devices. Ant i thought TRIAC's are for AC, whilst this is just a really big pulse of DC....well, i'm unknowledgeable, clear me up.

[padmanabhapsimha]

TRIAC's can be used to switch both AC and DC. If you use it to switch DC, it works exactly like an scr It basically acts as a two way SCR. SCR's/ TRIAC's do have a breakdown voltage but it is usually in the range of 600 to 800v when forward biased. If you closely look at the datasheet of a 25 amp scr. It says that the surge current is around 250 to 300 amps for 16 to 20 milliseconds. you can usually overshoot this rating if your coil gun resistance is low enough and your caps discharge in a short time. I suggest you search this in wikipedia. moreover they are more compact and way faster.

[phevtron]

i tryed to connect a 400v pc pwer supply capacitor but iron just moved a bit...... whats the prob with that? too many ufs?

[eggman]

if you mean you connected it to a capacitor from a power supply, then its probably about 220uF, right? for my gun, i use 3900uF but anywhere from 1000uF to 5000uF is good as long as your coil is optimized for it.

[phevtron]

i first tryed with two camera capacitors 160uf and i was able to throw a small piece of iron ( low speed)
power supply capacitor didnt do anyrthing :/

you recomend 1000-5000 uf for every coilgun?
oh and something i thought of right now XD what is better ?
two coils or one coil with the same lenght ?

[eggman]

for my purposes, i use a minimum of 1000uF per primary coil. i also use coils that are the same length as the round i plan to fire, and about 15-20 layers of wire.

[phevtron]

ok thnx :D :d

[kikazz]

I see you use pvc in some of your guns. perhaps you could rifle some of your barrells with heated metal to stablize your bullets?

[badideasrus]

they sell rifled pvc. look for spudgun sites.

[matiwariat94]

i tried this project not long ago using your guide, everythign was fine as i believe but i could never get the charger's to work and even fried a whole set once :(, after that i gave up. now im thinking of starting again and was thinking if theres a working alternative to the camera chargers? this help would be gretaly appreciated since the camera chargers seem to hate me after destroying about 30 of them from trial and error and never getting it to work. i might get pics of what i got right now if needed

[Blue_Bird]

You could try a voltage multiplier circuit, there's a lot of diagrams online, plus, its fairly simple to make, just some diodes and capacitors, but they take up alot of space if you want a high voltage.

[urbanprimate]

This is absolutely amazing!  The only thing I'm missing are the cameras, and there's a cvs 2 blocks away...I can't wait to make one!  I wonder if a license to carry a sidearm covers this sort of thing.  Generally I hate when people argue the law on these sites, but it would be even better if I could put it in a holster and take it to a firing range.
Either way,
you, sir, are my hero.  This 'ible is packed with useful info.

[McGenius]

IIRC, the law defines a 'firearm' as a device firing a projectile by means of explosive. In this manner things like airsoft guns and pellet guns are not legally considered 'firearms'.

But, it doesn't give an excuse to treat it as if it was not a firearm, as in safety. like, don't point it at a cop?

Just my .02.

[gammaraptor]

you made this on vacation? 0.0. Nice job by the way haha. now i'm going to make one for my science fair project xD

[dallusdapwnage]

Anyone got the specs of the transformer and resistor on the charging circuit.

[rwilsford07]

Here is an equivelent kodak circuit.

[dallusdapwnage]

thanks heaps

[D4NG3RNL]

What program did you use to simulate the circuits?

[D4NG3RNL]

Nvm

[the "wow shammy"]

where can i get this Nvm?

[Arbitror]

Good times...

[D4NG3RNL]

NVM means  nevermind....

[~ZOMG]

He's joking.

You couldn't figure that out?

[alvaromanuel]

lol

[shawntherobot]

how did you get the casings for your guns and couldnt you just charge a capacitor then attach it to a coil it it will fire something

[NerdofSteel]

so how fast can this thing shoot?

[jdc187]

I'm very interest in electronics however don know alot about the math and science behind it. this looks like a great project and im just curious would larger capacitors or longer coils increase the velocity of he projectile??

[moshee]

there's a limit for everything. A longer coil might increase performance, but to a point. same with capacitors. The only way to know for sure is use the simulator or try it yourself

[BeanahVulgaris]

Holy....

Man, thank you for promoting good design.

I have a few ponderings though,

1. would a bifilar coil help? if i remember correctly, the hookup tesla used in his patent increased the self capacitance of the coil.
(picture of this) http://en.wikipedia.org/wiki/File:TeslaBifilar.png
(patent number: 512340)
the first spiral of the coil he designed he said, if it had 1thousand turns and 100 volts placed between the terminals, he would find 1/10th of a volt between each turn (the internal capacitance of the coil). He said the difference of potential between the two spirals would be around 50volts.

He also said that this design destributed the charge evenly throughout the conductor (which i guess reduces capacitance failure due to imperfections).

Im guessing if you kicked afew of the pancake bifilar coils in series, dont know about the distance between them, (maybe add multiple coil stages using optical sensors? )

comment on what your thoughts are :).

thx for your time.