Coil Gun

What are you trying to build ?

I hope you're not trying to create a magnetic field with capacitors.

You're partially correct in your understanding of capacitance. Obviously, we're STORING electrons with a capacitor. The greater the area of the plates and the closer they are (seperated by a di-electric or insulator ) the greater amount of energy they can store and deliver.

Here's some useful formulas: E_{n =} C*E² / 2

E_n = energy stored in wattseconds or joules

C = capacitance in Farads

E = voltage

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Reactance: X_c = 1 / 2∏*F*C where X_{c =} capacitive reactance

F= frequency in hertz and C = capacitance in Farads

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And Ohm's Law: I = E / X_c where I = current in amperes

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Capacitors in parallel will ADD their rated capacity but the maximum voltage to be applied must not exceed the capacitor with the lowest rating ( if different )

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Capacitors in SERIES:

capacitors in series REDUCES the capacity but adds the voltage rating as follows:

C_{t = _________1___________}

1/C₁ + 1/C₂ + 1/C_{3 etc.}

And voltage drop across each series capacitor is determiined as:

E_c1 = E_{t *} C_t / C₁

Is this what you're building? A coil gun? You're supposed to energize the coils one after another, pulling the projectile (usually made of iron, like a nail) along until it shoots out the other end like a bullet out of a rifle. I've built one of these but I didn't use capacitors to energize the coils. I used power transistors.

This thing is a little difficult to tune. I eventually found that the coils need to be energized in decreasing length of time. By this I mean that, the left-most coil is energized the longest and the last is energized the shortest. Timing when the coils were energized was also difficult. Furthermore, I needed to match the projectiles because a change in weight necessitated a change in tuning.

This was a fun build.

It's single stage for now. Iron hasn't been working for me. Apparently Magnetic permeability is an issue on this small of an application, iron, and iron alloys are too easily magnetized, which negates the field of the coils acting on the projectile. My biggest issue is the low velocity of my projectile, I'm not sure whether that's the permeability, or the current. I'm guessing the current. I need more capacitors! TO THE PHOTOSHOP!

Now... on a multi stage design like you have, did you time the coils using resistors and inductors? Or did you have some kind of computer? Also, what was the velocity of your final design?

iron alloys are too easily magnetized

Yes, I had problems with that too. I was thinking of using AC instead of DC but never got around to it. I was having too much fun with the thing!

My biggest issue is the low velocity of my projectile

I believe that's one disadvantage of the single stage coil gun. With multiple coils, the projectile is accelerated by the coils as it travels up the tube. The farthest I ever got was about six feet with three coils. More turns, more current, more coils and I might have had a monster gun!

I used PVC piping, magnet wire for the coils (no iron cores). I designed the circuit so that I could vary the length of time that the individual coils can fire as well as the intervals. I did this with simple 555 timers. One improvement I thought about (but didn't implement) was photo sensors just before the coils. The sensors would detect the passing of the projectile and switch off the coil and switch on the next one. It eliminates the necessity of tuning and the circuit can be much simpler.

It's been decades since then. Your post has got me thinking about improvements to the original idea.

I'm thinking that if I energize all the coils at the same time and just switch off the coils one by one as the projectile shoots through the tube, I might get better velocity. Also, using AC on the coils should help prevent magnetizing the projectile.

'So, Ohm's law would dictate that the voltage would increase as the current encounters the resistance from the coil.'

No..Your voltage is what you have charged the Capacitor bank upto.

How fast this will discharge through a coil depends on the resitance and inductance of the coil. The Resistance will resist the flow of current..the inductance will resist the change of current flow. (I'm ignoring back emf and all that in the name of simplicity folks!)

As you point out V^2 is a major factor, so use the max (safe ) voltage.

(a crossbow is simpler! Click ..thud..aaaargggh)

Plenty of info on the web on this subject.

http://www.coilgun.info/home.htm (lots of useful information and development here)

I would recommend Maxwell Ultracapacitors, their 350F 2.5V D-Cell ultracapacitor is the best value for money I have found, anywhere (at least 3 times as cheap as the nearest competitors product). Cheapest capacitance per dollar (I believe you can pick it up for something like $25 US dollars each). Safe working voltages too (just don't short the capacitor out and burn yourself, the internal impedance is very, very low which is exactly what you need for a short-duration, high-current pulse application like yours).

My rig is a bit bigger. It uses SCR's and instead of capacitors, and two oil-filled distribution transformers powered directly from the network's 11kV to give about 1MVA at about 10,000A for a second to simulate a power station driving a shorted overhead transmission cable. It is not specifically designed for coil gun research and does cost a bit more thou .

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"He who has the best toys, wins"

Sounds more like an EMP weapon! Does it pop all the Pcs in the vicinity when you fire it?

No, but when I have finished building it (nearly done), it will double the power used by the entire industrial park area it is located in for a very short time. Should be interesting the first time it is fired.

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"Where did he get such wonderful toys?"

Sounds like a great project, full of interesting design problems.

Ideally, the magnetic field would turn on as the moving slug approached and turn off as it passed. switching lots of energy in a short time through a load with a changing inductance.

It might be easier to start by switching a set of small coils (as already suggested). Perhaps you could make a long shift register (SR) using CMOS, clock it with a 555 timer, use a monostable to inject 1 bit into the input, have a set of coils driven by mosfet, you could then tap the SR at various points to drive the coils. for example SRbits0,1,2,3 - coil 1, SRbits8,9,10 - coil2, SRbits20,21 - coil3, SRbit40 - coil4. the 555 can be adjusted match the rate the slug is accelerating.

On a related note. Here in the land of OZ, some melbourne kids built a hairspray powered cannon to scare the flying foxes in a public park - they were hit with terrorism related charges. Make sure you're not creating a potential WMD. jeff

That photosensor idea is a good one. I think I might try it

Edit: What should I search for, photosensor switch? Also am I looking for a DPDT etc etc, or what

Concerning the permeability issue, why not try another material for the slug. I've been looking and thinking that one of these might work. Dysprosium, Gadolinium (however,kind of expensive), Manganese, Magnesium, Cobalt, Depleted Uranium, Nickel, Strontium, or alloys of any. All have a permeability greater than 1 but still low enough that the magnetism dissipates shortly(or immediately) after the magnetic source leaves it. But would paramagnetic materials actually work well?

Wait... i'm wrong with something, I just know it

Why don't you consider Bismuth? It is the most diamagnetic of all metals (-16 on the magnetic permeability scale) which means it is repelled by a magnetic field, instead of attracted.

I've made a similar project some time ago, but I used solenoid coils to create the force to propel a nail. The coil was just energized by a 220 AC supply and simply switched on and of. The nail shoot out only a few feet. Perhaps I could try this again with several coils in series. Another interesting project similar to the "coil gun" is the centrifugal gun. This can shoot BBs only or round lead pellets or small bearing balls. But it can really shoot to hit targets some 10 feet away or even farther if you make a bigger diameter disk or wheel to create the centrifugal force.

I hope you are making this coil gun as a toy and not as a weapon, you might need a permit to own one....

I hope you are making this coil gun as a toy and not as a weapon, you might need a permit to own one....

Nope, not a weapon. Just a summer project to keep my fragile, teenage innocence away from drugs and alcohol.

First, what the hell good is a coil gun without those last two ingredients you mentioned?! I thought they were absolutely necessary for the device to work.

Another thing (sorry if too simplistic) - think of electrons as baseballs. The speed of the baseball (it's energy) is Volts, and the number of baseballs thrown at any one time is Amps. The strength of your magnetic field is pretty much dependant on the number of electrons you can get through your coils at any one time. So you want BIG Amps. Also, when you try to slam a bunch of power through a coil, you have to take into account resistance, capacitance, reluctance, inductance, impedance, on and on...

Might I suggest looking at a few rail-gun designs. They don't use coils, which does away with a lot of that other stuff. Plus, a rail-gun is more dependant on a sudden change in current direction.

That, a bottle of tequila, a joint, and the local air port could make for one hell of a summer! IMHO.

You're such a bad influence...

Just let me talk to Dee Dee!!!

Oh! That's what you were referring to when you said you wanted to talk to my sister! Haha, I just picked this avatar because this one really hot girl at my school thought that I had a laboratory in my closet. The really sad part is, I thought she was joking around, she was serious.

OK, it just looks like I'm going to have to talk to Mandar.

By the way, what's the contact info on the dumb girl?

You guys have to give us Brits a chance here ! If your keyboard had a 'k' vermin , I would have saved 1 minute of my life by not getting diverted to Ramones site whilst figuring out you were talking about Dexter.

eesh - nutkin will have revenge. Probably with a Navy rail gun . You too can search (on CR4)

You're going to have to change back your avatar for that to happen!

You know perfectly well that nutkin is nursing your luv child. I'll tell nutkin to leave the kids on a drip and re-appear , everybody has been asking. Like am I too ugly or something ?

Ahhhh!

I geddit now! So that's why one of the guys at work calls me Dexter!(Or Deadly Del if I'm putting well...hey the rhymes...etc).

Women just don't get the projectile weapon thing!

Although one (rather attractive) divorcee had a play with my Chinese repeating crossbow with a view to turning her ex into a pin cushion.

I gave her very close supervision...(not as close as I'd have liked...D'oh)

wor Del is a git clever gadgie . He nees wor hes taakin aboot

Aha, just a toy! then you need not search for these metal alloys to use as slug. The slug need not be magnetic, could be of plastic or any round or projectile type object. You will need to lose a lot of these projectiles when you are eventually able to fire your gun. What needs to be magnetic is the rod that will push the projectile out through the barrel. Sort of hammer or ram to kick the slug out. Imagine the workings of the original Daisy BB gun? where there was a compressed spring that was quickly released when you pull the trigger?

Oh no no no my friend... I have one of those, it's called an airsoft gun. I'm ready for the BIG toys like coil guns and jet engines and soldering irons!

You do have a sound idea. But the same permeability/permitivity dilemma would persist with the ramming mechanism. On an amateur level, it is impractical to ram the projectile, when the mechanism ramming the projectile makes a better projectile in itself. Projectile! Projectile! Projectile!

The beauty of EM Coil guns is that they use few, if any, mechanical parts. Really the only things that move are the trigger and the projectile itself.

Anyway, I think I've found that my best bet for projectile material would be a silicon-steel alloy. It has the permeability necessary and it only retains very little magnetism, and that which it does retain will dissipate quickly.

Your idea is very good, we're just thinking of two different things.

I'm just sayin' High voltage, tequila and a joint. Huh? Huh?

perhaps you can try ac & wind it like a linear motor like the maglev train

By the way, I know a Venkat... Just how many people in India are named Venkat?

It is a very common name in South India, particularly in Tamilnad (good old Madras) & Karnataka (Bangalore).

I have dismantled (broken??) enough things to call myself an engineer apart from my degree in mechanical engineering. Started with my grandfather's watch when I was hardly 4 years old and continue even now (59 years old now). The only difference is I get paid for it now.

At four, you must have had a very nice grandfather!!!

By the way, I have a friend with a vanity license plate that says "MAD MALU." He's from Carolin. Anywhere near where you come from? I'm stupid when it comes to Indian geography.

Malu is a shortened form; Most likely it is the name of a girl. Could be from any part of India.

I am equally weak in geography. I'll have to look up where Carolin is.

LOL....

Carolin......Presumably..also from a girls name....

These girls eh?

In the UK , we have this thing called 'google' Do you think it will catch on ? Lord Kelvin says no way. Leicester (UK) has a very diverse Indian community - a Sikh friend told me of this rather odd site.

Till recently, we also had a lot of Englishmen in India. Perhaps, they are reaping what they have sown. I spent a month in Rugby last year. I saw a lot of Indian restaurents(??) there even though the Indian population there was quite low. I loved the Guinness

Most of the Gujaratis (from Africa) are in Leicester; I saw a lot of Sardarjis (sikhs) in Birmingham; (officially there are 26 languages in India & UK was the only place where i had no language problem); perhaps London has the most diverse Indian diaspora

Hi venkat,

The Brits ate pretty much in love with Indian/Asian cuisine , but it is probably a lot different in our Indian restaurants to the real thing - I'm told that 'Chicken Tikka Musala' is a purely Brit creation ! Long ago I lived not far from Rugby. Check out Leicester and Diwali - sounds really good , though I've never been there at the right time. Britain has a very diverse and much respected Asian population . Also the new Sikh temple is a good example of Indian culture in Britain.

I really enjoyed my stay in UK. Everyone was very warm & friendly. But I was sad to note that manufacturing had taken a back seat in UK (our company had bought 3 plants that were closed). UK has become a nation of bankers accountants & insurance agents. It was too much for a hardcore engineer like me to stomach.

Most of the 'Indian Restaurents' were run by Bangladeshis (from Sylhet district). The food was quite good - mostly punjabi dishes, modified to suit the British palate. Anyhow this case is not like the Chinese dishes available in India - in China they had not even heard these names.

Hi...interesting post..yes we can thank Margaret Thatcher fot the loss of much of our engineering.

It's a shame, most people here think an Engineer is the man who fits their dishwasher.

They happilly use their PCs, mobile phone and cars without realising it's us engineers and 'nerds' (don't you hate that expression) who invent, design and build these things.

When I'm asked what I do for a living, I watch peoples eyes glaze over when I say 'I design electronics and write software'.

They'd be more interested if I said I was child molester!

Hi, Everybody blamed only Margaret Thatcher. My heart bled when I saw the Alstom shed where Sir Frank Whittle developed the first jet engine during the war & the DAF/ ERF truck plant were used as warehouses.

In India everybody wants to become a software professional - I have enough in the family. A mechanical engineer like me is a poor cousin these days.

ain't that the truth. Britain plc is all about service jobs , nonsense job titles and non-jobs. Actually doing something constructive is seen as some sort of failure. The economy is a house of cards , waiting to collapse. 99% of people would have no functional skills if stuck on a desert island. Oh dear.

Wow... That rate is lower in America, though that might have something to do with the obsession of cheese in California, Vermont, Wisconsin, New York and lets not forget the famous Mississippi State University Cheddar cheese! Also, the obesity epidemic has made more(though only slightly) people concerned whats in their food.

Great cheese link ! Bureaucrats in the EU would probably go nuts about the thought of 'Cheddar' being made and sold in the US. People have to live with all sorts of labelling directives here. For instance products such as Melton Mowbrey Pork Pie and Cornish Pasty have to be produced in specific areas if they carry a regional name. It's the same all over the EC. Trouble is that subtle changes in wording of labels can get around this. The whole thing is a typical EC fiasco.

Make more Cheddar America ! It's probably just as good as our version.

I have to admit that some products probably do require regionally unique conditions (wine for example) to produce. I see no reason why the 2 items I mention can't taste just the same if made elsewhere. The UK produces small amounts of wine , but if we produced a sparkling one and called it Champagne there would probably be another war with the French !

Make more Cheddar America !

I say...steady on old chap!

Hey , you're reading my mind Del ! I was trembling as I typed with the words 'traitor' whispering in my ear.

On the balance side , you do give me a chance to say 'too late - hard cheese'

Sorry Blighty. Dashed bad form of me , what. Got carried away y'know. Sorry.Well ,, well no , double sorry and hope to suffer hideously for it . I'll bally well make up for it somewhere. Dashed colonial types just sort of seduced me with cheesy delights. Enough to make a Welsh Rarebit blush.

I have to admit that some products probably do require regionally unique conditions (wine for example) to produce.

Anything that has to be grown or caught(plants and wild-caught fish). Things raised don't depend on a region(like veal{baby cow} or farm raised fish). Maybe we could use this as a rule of thumb on whether or not something depends on a region for value or quality.

I'm not so sure.

The quality of produce from an animal is often promoted as being due to location ( ie not just due to specific breed). This may be complete bull (ha, couldn't resist a pun) for all I know , but farmers seem to say so. Most animals can live on different tpes of diet , and so it seems reasonable that this may affect taste of meat. I'd guess fish is pretty much fish though. Who would have thought that a coil gun thread could end up needing a Farmer ! One will eventually arrive here and save me/us.

First, if you look at knife catalogs at all, you'll see that several types of knives cannot be shipped to CA, WS, and NY. I thought this puzzling until I found out about the wild and violent cheese gang life being played out on the streets of the urban areas of these states. It appalling!!! For God sakes! When are we going to wake up and realize that knives don't kill people, cheese cutters do.

On a different note, what you suggested about the food swapping has been going on for years. A long time ago, UC California came up with the perfect conditions for creating Roquefort cheese (this is like the heroin of cheeses). However, France would not let them use the name because it referred to a specific region in their country. That is, until one day, France was looking for a pear that would continue to ripen after if was cut off the tree - they wanted to create a brandy that contained a full grown pear in the bottle. Tastes good, and makes everyone crazy trying to figure out how they got the damn pear in there. It turned out that UC California had a pear that would do this, and France turned over the rites to the Roquefort name to get the pear. See, I told you alcohol can be educational!

heroin of cheeses

Brilliant phrase v !

It warms the cockles of myheart to hear of thr French food fascists being forced to climb down. Are the French unable to figure out how to get a pair in a bottle !! Even the French aren't that bad.

Have a look at www.tesladownunder.com - one of the most interesting pages for everything burning, flashing and flying with hi voltage/ hi currents.
Regards Uwe

The next generation of USN aircraft carriers will use rail guns instead of the conventional steam catapult for launching aircraft.

Have any of you tried using a sabot to contain your missile? One problem encountered is a stickiness between the tube and the missile sabot. This could be overcome using a technique used in self levitating rail technology thus eliminating friction up the barrel of your supergun, and if the barrel is essentially plastics construction it won't be confused with drilling pipes when you take it on holiday.

I'm not using a sabot due to this issue, I'm using a solid slug about 3.5 mm diameter.

Couldn't you fit small electrical contacts along the length of the plastic tube - the travelling metal projectile would then switch the next power pulse at exactly the right time to get maximum thrust and minimum magnetic drag. Easier to build than a complex timing circuit.

No, the timing of the short-duration high current pulses has to be precise (and repeatable) or all you will do is slow the projectile by firing at the wrong time. There is no easy way of doing this (or precisely altering the timing) mechanically.

A single coil, properly setup and powered, with a correctly sized metal projectile (not too long and not too short) still seems to produce the best results for your average user, and is soooo much easier to construct and tune.

OK, if you really want to be on your way to killing some poor Innocent bystander, take a lesson from SLAC...

The tube of the gun is surrounded by coils, each coil is shorter than the one before it, but has the same power. As the projectile move down the tube, it gets the same magnetic kick, but for a shorter duration. Now comes the question: Can you make the coils shorter, but produce the same power?

Why complicate things?

Each coil is the same size and number of turns but the electric pulse is shorter. If need be, the voltage and/or current can be varied also. Easier to tweak things electronically than mechanically.

"Why complicate things?"

On the contrary, your idea takes a bunch of circuitry to make shorter pulses. On the other hand, my design can use the same power across all coils. Additionally, there's an effect here that's something like pumping a swing. Each push has to be timed just right. Not only does the projectile get the same push, but it's applied for a shorter duration and for a shorter distance (the width of the coil) within the tube.

Sounds like he's making a linear induction motor to transport beer kegs into space.

We can make life even more interesting on the ISS.

As Vermin pointed out "timing is everything". The projectile must be pulled along the barrell constantly. If for one split second you capture your load in the middle of your coil, you have applied your brakes.

Well i must say that there are 2 winners today: this thread and the 'Bermuda Triangle' one. I LOL'd at both.

Would you care for a few receipts on how to cook brazed Welsh Corge?

No thanks V, I don't keep receipts for my food. Does sound interesting. Ok, shoot.

Have you been over here vermin ?

Yeah, I saw a picture of the guy doing it! I think it only turned out to be dachshund or poodle, though.

Must have been the Daschund - right shape for a hot-dog bun. Also , Podles are to hairy.eugh. Maybe I could have helped.

If I know you, you were their ring-leader!

So how difficult/expensive would it be to set up a laser or photosensor trip switch?

You're thinking digital when you should be thinking physical! If you're going to make more than a pop-gun, you gotta start thinking kilowatts at the very least... The power pulses you need to get respectable velocity will cook your silicon circuits just from the EMP given off when you fire the thing!

I suggest more delinquency to get your mind work on the right track.

Use SCRs

Can be fried too. A heavy-duty-coil relay, with fast-enough reaction-time? Wait! no-good. The coils may be charged to false release, by residual field.

Maybe that's why we are not the ones to build it. Do you have to join the Navy to be allowed to mess with whole farad's worth of capacitor charge?

The SCRs we use here at work (also used in magnetizers) can handle 400A/600V with KA surge ratings. It'd take a hellofalot to fry one of those (large) bad-boyz.

As far as the triggering goes a bright tungsten light source and cadmium sensors might be able to withstand the EM pulse..

Wheres my Corge recipe V??

No, you don't have to join the Navy to play with Farad-sized capacitors (you can buy 350F 2.5V ones now), just a little knowledge, common sense, and of course safety.

With regard to the relay, if you are using capacitors to power the coils you will find that the contacts of even the largest contactor will not survive the very high peak spikes of current. SCRs are best for the larger rigs (and suffer no relay contact bounce!), but of course require a bit more knowledge of things like the firing circuit.

Basic SCR firing ckt not too bad. a resistor going to bus+ and a switch (transistor or magnetic reed ...

wait....moment.....idea ....coming ... 1st coil fires closing reed switch going to second coil scr gate -firing 2nd coil closing 2nd reed sw going to #3...and so on..

Good point. A Faraday-cage made of led?

yeah! wouldnt lining or making a shield or faraday cage over a simple photosensor switch circuit take care of the issue(or lessen the effects) of EM exposure?

As in real-life, a cage works both ways:

Cage a sensory circuit and it will protect from EMP damage, but also block from sensing properly.

As in real-life, careful balance can maintain some order to a degree of functionality.

Nuff said.

OK, I'll give some you insight into how this is done in the real world...

I have a friend that worked at Westinghouse in the days of Star Wars. They were asked by the DOD to create a viable rail gun. Here's what they came up with...

A large chamber filled with really, nasty, big coils. In the center of this chamber most of the available space was taken up with a several ton weight that spun on an axis in the chamber - it was like a giant, single poled, electric motor. When they got the weight up to speed, they stopped it as fast as they possibly could - stopping device was a huge brake shoe that was fired at the weight using a large explosive charge. It stopped the weight almost instantaneously, and the built-up magnetic field collapsed and fed an enormous pulse of EMF back through the circuit and down the rails.

Of course, for each shot, the chamber had to be completely rebuilt. Also, the force down the rails always snapped all of the several hundred ¾" high-tensile steel bolts that held them together.

So, you might try something like this, where you build a device to store energy, stop it fast and use the EMF to drive your slug.

You will find that the EMP given off by the rig is not actually that bad (current spikes on switch contacts in the discharge path are very destructive thou). I should be firing up my rig (similar to a coil gun but ac, 1 big loop, and used in a more constructive manor) within a few months so I will let you know how it went. No I don't use a big knife switch <insert mad scientist maniacal laugh here>, I use 4 of the largest available Hockey-puck package SCRs in a back-to-back configuration.

(See post #5)

And slightly off-topic:

to be found HERE with cream, or HERE without.

Now that's clever.

At first sight , I thought somebody had lost their dentures. It's completely barking mad , absurd.

Very nice.

"...lost their dentures..."

But it is, it is. The bowl on top is to contain the dentures, dipped in hot milk, to giv'em the right flavor, before orally fitting them.

To backquote: "It's completely barking mad , absurd."

Ahuja- have we helped you in your design yet?

Good points.

I hope we haven't put Ahuja off Engineering as a career. Still , a sense of humour is pretty essential. Also , a lot of the really good Engineering is in posts made when things go off topic. Too much focus probably causes more Engineering disaster than too little. 'Tunnel vision' is the metaphor I think.

I don't think so. He's probably just muttering to himself "bunch of crazy old geeks" and getting on with his project.

I do hope he's careful though.

"bunch of crazy old geeks"

Yep. However, you have been helpful. For the moment I'm tinkering around with a single coil, and I went down to RadioShack to see if I could special order some stuff. Not much to pick from.

I need to go to a machine shop or steelworks or something and see if I can have some silicon-cobalt steel slugs made up for a reasonable price. What I'm looking for is something maybe 4.5mm diameter by 9mm cylindrical. What I then do after I find the time it takes for the slug to travel Xmm down the barrel, thats when I plan to choose the place to put the next coil and use a timer circuit or something. Then the same from the second coil to third coil, and maybe if I don't get overcome by teenage apathy and laziness I may add a fourth coil doing the same thing. I need to find a suitable material to mount the thing, I just build the circuits on a PC board.

Also, I went to my local Kroger(a supermarket) today. I caught them in a lie! Last time I went and asked if I could have the disposable cameras they would throw out anyway, they said that they usually send them away, but they would give me some anyway. But today, they tell me one of the employees forgot to take yesterdays cameras to the dumpster! So i got this big bag of 40 of those little things, and now I have 14 80uF and 24 120uF-(the other two cameras didnt have flash circuits )- Capacitors on top of the god knows how many others i have. Anyway, I also got a big thick catalogue from Digi-key, I never asked for it. Maybe they sent me it because I registered with globalspec. But there were some nice big 70F aerogel capacitors for about $20 a pop. Gotta start saving, or just stick with the bank I can make with what I have.

Also also, I didn't reply sooner thanks to World of Warcraft! My friends were right, it is addicting(like heroine, exept I don't get AIDS or hepatitis!)

Just remember one thing, it's good to have high-capacity capacitors, but you also have to account for the speed at which they can be discharged. For instance, there are some really big electrolytic capacitors on the market, but they can't be used for flash circuits (both photographic and laser) because they discharge too slowly. Instead, oil-filled and ceramic capacitors are used because you can get the stored charge out really fast!

Good luck, and remember the left-hand rule!

You could find stuff here maybe. At least it has some warnings.

Ahhh- ol' info-unlimited. I bought my 1st hene laser there years ago.

They got some good stuff, but sometimes they're full of B.S. You can't use a 5mw he-ne laser for "cloud illumination" as stated in their catalog.

I'd never heard of them before , but it sounds a whole lot more fun than RadioShak / Tandy. Our main man probably knows the company , but what the hey. I'd have been all over stuff like that years ago. A 'Danger' sign is the biggest come-on I know.

(Just don't fry yourself Ahuja).

You can if you've got photomultiplier tubes for eye bulbs!

I got a toy lightsaber from them a long time ago

I haven't been there in forever. lets see what they've got

Was your On topic link there just to exempt yourself elegantly into further contemplation in this hot topic of flavoured dentures ?

Because if so, this is the time and place to rebuke yourself, standing in the corner facing the wall, mumbling "I'll never think of dentures again" a thousand times, than spanking yourself three times, before leaving the class forever.

Go wild, go the Israeli way. Go intimate with what you have no idea of.

I believe that Dexter's returned to his closet lab..

....or found a safer hobby like vermin so wisely suggested.

There are no words to describe the shame I feel .

Sarcasm. Yes, can't beat it with a stick.

I don't know if anyone found or posted this site already, but this guy is going to sell kits for a real working gauss pistol. He even has videos of it and explains how it works. Very complete, check it out:

http://www.gausspistol.com/index.html

(Sorry, the create/insert link button isn't working for me)

-Nick

I'm taking orders for my plans on how to build a zip-gun.