Clyd3

so i take it that firing too much in short succession would result in dynamite breadboards and dodgy croc clips as a result of heat buildup?

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Nigel Goodwin

I think the 500A figure is only complete guesswork?, and certainly if it's wired on a breadboard the resistance of the connections and wires will limit it to far less than that. As well, the high current will only be a very short pulse, which rapidly falls away.

Building it correctly, with heavy wires and good connections, will probably improve performance?, by allowing a much higher current pulse.

So, short thick wires, and the absolute minimum of connections in the current path, would be the way to go. A breadboard and croc clips are about as bad as you could possibly find!.

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audioguru

I agree that the decimal point is missing. He would be lucky to get 5.00A with those flimsy connections. :lol:

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Uncle $crooge

Someone Electro

You ceranly wodnt be able to blow an hole right trough 8 sheets of alu foil whith 5A.

And til now i didnt have any sparking on the joints.

It clocked 31km/h for the small projetile and 22.5km/h for the big projetile.

Nope evryting seems to work fine. If the joints had resistance they wod cetanly spark.

But if an wire is contacting somting whith its tip it makes an big flash and makes an hole.The breadards contact seem to "hug" around the wires enugh to give virtualy no resistance to it.

So breadoards give low enugh resistance joints to take 100s of amps

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Someone Electro

Oh and heres an comented photo of it.

The fire switch is stuck to a bell whith duck tape.(The bell was perfect becose its heavy and dosent tip ower likely)

Meaby il also make an video of it.

Attached Images

coilgun_v2.jpg (187.1 KB, 360 views)

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audioguru

Current doesn't do anything by itself. It is the amount of power that does work.
You have about 300V, which times the 5A current equals 1500W!

If you had a rediculously high 500A, then at 300V would burn a hole in a 1metre thick piece of steel! That's 150kW! :lol:

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Uncle $crooge

jrz126

I can get my hands on some rather large caps from work. I think they are like 200,000 uF with a working voltage of 63VDC.

Have you thought about rewinding your coil? you might be able to gain alittle more if you had it wound nice and tight.

Also, how exactly are you measuring the velocity? I saw you had a microphone in the picture on the previous page.

I think I might have to start playing around with something like this. :twisted:

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Jeff Zimmerman
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To the pessimist, the glass is half empty.
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Someone Electro

You may have an problem whith such big caps becose you wont be able to fuly discharge it in the coil.It may be porsible if you wire then in serial for an higher voltage.

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Someone Electro

Oh and how i mehure the speed.

Simple realy.I just record the fireing.Then whith audio edidting software i meshure how many miliseconds is betwen the fireing click of the coil and the sound of the projetile hiting a box. Then i can cauclate the speed.

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audioguru

With a huge value cap then the coil will still be energized when the projectile is trying to leave the coil. Therefore the coil would try to pull it back, putting on the brakes big-time.
The most effective way to control the coil would use a photo-detector to turn off the coil when the projectile reaches its center. Then all the power of the coil would be used to accellerate the projectile.

If the projectile is magnetized, the polarity of the coil could be switched to pull it in then push it out, doubling the thrills. :lol:

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Uncle $crooge

Someone Electro

Yea the puling back.But the problem is if you thurn off a lot of the charge will stay in the cap. You cod serial more caps for an higher voltage.

My projetile got magnetised becose of the strong pulses.It can get magnetise prety good after one fireing. But that is nothing compared to the huge field around the coil.So for this you wod need an rare earth magnet,wich are extremly powerful.

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Someone Electro

Ok you guys heres an video of it:
http://media.putfile.com/Coil_GunV2

This time i videod 10 shots.

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audioguru

I couldn't make your Putfile video do anything.

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Uncle $crooge

Someone Electro

I can see it. Its DivX encoded.

Check the you have an DivX codec.The audio is an MP3 stream.

Media player says "conecting" and firefox is saying "transfering from putfile.com"Then sudenly it starts playing.

You have to give it time to load

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Someone Electro

I made some biger projetiles out of nails.And on one i left the sharp point.

It makes holes in thin cardboard and makes a hole in a can.But the hole is litle so that the projetile cant go trough.

I had to use an new barel becose the nail was way too big for the old one.So i had the floor full of wire from the unwinded coil that i had to wind around the new barel.

Also i wod not like to put my hand in front of a big nail traveling at 21Km/h.

The nail is 11,5 cm long and 4 mm thick.

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