Coilgun SGP-33 assembly and test

[@skeptical_thinkers]

Wow I'm impressed you got the LT3751 circuit to work. I was banging my head against that circuit for about 3 years before I finally gave up. Congrats. I think you're one of the only people in the world who has ever gotten that chip to work.

[@howtomakeacoilgunoffallout4096]

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[@NNNILabs]

Wow, this is a really neat build!

[@tomtechtod9200]

Thanks!

[@NNNILabs]

You're welcome! Don't you think using pon headers to connect the capacitor to the main board might add unnecessary resistance? I thought the high current path must have the least possible resistance.

[@tomtechtod9200]

Yes , it adds resistance. But this resststance is very low and has therefore nearly no impact at this voltage. The main limiting factors here and reasons for low efficiency are the high ESR of the cap and projectile saturation.

[@NNNILabs]

I'm trying myself to build a railgun on this scale, and every single milliohm can lead to tons of losses. I'm using two 200V caps in parallel to reduce the ESR and ESL instead of using a single giant cap. I find it interesting that you use IGBTs to switch the coil. I suppose they can turn off when you need them to to reduce suck-back. And they don't have to handle that much current, since the impedance of the coil reduces the peak current. Railguns have really low inductances and need nasty currents, in the order of several kiloamps for a short while, so I'm using some fancy SCRs.

[@tomtechtod9200]

actually bigger cap doesn`t necessarily mean higher ESR. I got some for testing 130mF 63V and 16mF 450V with 9mOhm and 16mOhm respectively. yes, i wanted to turn off the igbt at a specific time, and they only handle a couple of 100A, not kA as in a railgun. For hobbyists I guess higher efficiency and durability is easier to be achieved with coilguns, I`m working on a multistage design now. Good luck with your RG

[@kallgakr1273]

Hello, i have a question: I ordered a step-up booster a while ago that consumes a maximum current of 5 amps at 8-32v. I wanted to power this with my 3S 5000mAh 80C Lipo battery and connected it directly to the booster. Shortly afterwards the 10Ah protection of the converter popped through, which did not happen to me with my laboratory power supply, that can only give a maximum of 10Ah. Now my only logical conclusion is that the battery feeds too many amps into the converter ...... But before I did always assume that the current automatically adapts to the consumption of the end device? how can i connect the battery now to the device without blowing it up?

[@tomtechtod9200]

The battery will only provide the current the load will demand plus the loss caused by the efficiency of the converter. The behaviour you describe could be caused by various reasons. Hard to tell over messages

[@howtomakeacoilgunoffallout4096]

Hey. Oh yes of course... See also New Portable Super Coilgun: kzbin.info/www/bejne/qJTPfaaHbtOsm8k&feature=youtu.be kzbin.info/www/bejne/Y57NdaSmlNSKkM0

[@javiermoran2223]

Hello Tom. Could you get away with just one IGBT?.

[@tomtechtod9200]

Yes, one IGBT one diode config is possible, but the current takes much longer to decay , I guess it will decrease velocity

[@himanologanor4093]

-nice work, i didn`t knew those small SDM capacitors are polarized, i don`t see any mark on mines, how can i detect the right polarity or was it just a bad design of the board and needed rotation ? -i don`t think that big capacitor was designed to discharge instantly, maybe a couple or more smaller capacitors in paralel would be better. -any chance you make a multi-coil-gun with delayed action between coils so that the projectile accelerates over a longer distance in the barrel ?

[@tomtechtod9200]

himano loganor yes the smaller electrolytic caps are polarized, probably bipolar exist too but are less common. I'm working on a multistage design, yes. The big cap was cheap. ESR is about 350mOhm, so not really low, better would be film capacitors or larger electrolytic caps, both of which will have only a few mOhm ESR. Verifying the datasheets of several caps I didnt see an advantage of using many smaller ones...

[@himanologanor4093]

smaller capacitors have about the same wires inside, so more of them equals thicker wires, i was thinking about short ones as well so that you can mount them directly on the board, no second board needed especially for the big capacitor. I had a problem once with one of these biog capacitor, the wires melted inside the capacitor , imagine what happened next...

[@tomtechtod9200]

himano loganor the only higher voltage caps I've seen so far that have an actual very short term discharge rating are polypropylene film caps, but then 1000u are about 4x larger... I am not really concerned about anything melting because the duty cycle is very low + the charger cannot provide high secondary current. Anyway, to increase efficiency , multistage is the way to go... I won't invest in single stage designs, except later maybe for induction style launchers...

[@himanologanor4093]

i`m dreaming of a multistage too, already bought 2 barrels from an airsoft store, had a magnet with me for testing, bought 1 nikel-crome and 1 aluminum hardened, 2 feet long each. Copper and copper alloys can`t be used since they`re diamagnetic, steel also no for containing iron. Bought 2 pounds of steel balls for them from a bicycle store , fits perfectly. Testing with 1 coil was simple and i used capacitors from computer power supplies , i still have like 80 capacitors from those PS in the garage and all in good shape, never saw one burned while repairing PCs. The multistage machine will be harder to fiddle with for max speed...

[@ksatriagembluuung1309]

Waaaauuuu Beautiful Gun. How Much you build that Gun??? How Much that? Please

[@tomtechtod9200]

everything is in the description or instructables

[@howtomakeacoilgunoffallout4096]

Hi! Oh yes of course... See also New Portable Super Coilgun: kzbin.info/www/bejne/qJTPfaaHbtOsm8k&feature=youtu.be kzbin.info/www/bejne/Y57NdaSmlNSKkM0

[@UKMrMedical]

Dose anyone no where I can buy a 3D print kit also for somthing like this there used to be a website a few years ago but i don’t no now please help guys I really want one of these coil guns as a kit or pre made

[@giannivergine1156]

I really wouldn't suggest doing this because 500v at this capacity is more than deadly. You should engineer it yourself. When doing so you'll understand the principle and dangers behind it which are extremly important with such dangerous stuff...

[@bitsurfer0101]

@@giannivergine1156 I agree

[@okay8632]

The lyrics to the first soundtrack in this video is 'narcisistic bitch' by doctor phill

[@meawreg]

the more I learn, the dumber I feel.

[@howtomakeacoilgunoffallout4096]

Maybe , maybe. Hi! See also New: Apocalypse Coilgun, Fallout Coilgun kzbin.info/www/bejne/fWqQm36Nhd6AfNE

[@lhtyeehaw1319]

I need a simple to make a simple, hunting grade version of this

[@tomtechtod9200]

Not gonna happen anytime soon.

[@johnnykatze7467]

If you want to kill deer or something with a coil gun, you should probably build a railgun, coilguns simply aren’t that powerful

[@lhtyeehaw1319]

@@johnnykatze7467 good point, would my nuclear generator be powerful enough to power it? Genuine question

[@johnnykatze7467]

@I failed the turing test Yes. the way to store electrical energy for a hunting coil gun would be capacitors. Lets say a deer takes 300 joules to kill. You would need to put about 30-40 of those big capacitors (like the one in the video) in series. This would be hooked up to a 14 - 16 awg wire coiled around 800- 1400 times. The whole contraption would weigh around 50 lbs and would shoot a bullet about 6mm in diameter. I think you would easily be able to charge them from you reactor at home, however without knowing specifics i can't give a definite answer. Again im just a kid who plans on building a coilgun. While i am fairly knowledgeable on the subject, I did learn a bunch of new stuff from this website: Coilgun.info

[@lhtyeehaw1319]

@@johnnykatze7467 cool. I'm just a bot

[@howtomakeacoilgunoffallout4096]

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[@howtomakeacoilgunoffallout4096]

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[@howtomakeacoilgunoffallout4096]

The current model of heavy-duty coilgun - increase in efficiency: kzbin.info/www/bejne/qHradI2rg8ygl80