How to Make a Coil Gun using a Fly Swatter 

Maybe, maybe ... See also: Nueva Super Coilgun portátil: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rclLsQ9nyeg.html&feature=youtu.be ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--mjDqp_oWZk.html

Thanks!

Mine puts out DC voltage. See this other video of mine ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-31Rxi8JMIys.html were a little past halfway, I take it apart and examine the circuit inside.

then i suppose i cant make this project , my mosquito racket outputs ac do you know any other way to get sufficient dc voltage , other than by using a fly swatter. @@RimstarOrg

Thank you for your response , to do have any recommendation on alternatives to the mosquito racket@@RimstarOrg

I realised my mosquito racket does indeed output dc , the manuel was wrong. anyways thanks for your help anyway@@RimstarOrg

I'd want to get some assistance because I created the coil gun but used other parts. I used 14 gauge copper wire and a 450v, 470uf capacitor. It did not work. It functioned more like a spot welder. So I'm curious as to what went wrong. Was it the low capacitance, or the thick copper wire, or a mix of the two? and can i salvage this faliure @@RimstarOrg

Thanks.

I don't know all the calculations that would be necessary off-hand. You know two things to start with: the voltage, current and hence the power of your bug zapper, and the mass of your projectile and how fast you want it to move. It sounds like you also have some capacitors already so you have their voltage ratings and capacitances. Probably work backward from the projectile mass and desired speed to figure out how strong a magnetic field you'd need. Then how much current you'd need in order to produce that magnetic field. At that point you can design your coil and then figure out how much energy you need to discharge from your capacitor bank to produce that current. The formula the energy in joules in a capacitor is 0.5 x capacitance x voltage x voltage (E = 0.5CV^2). So once you know the energy you need from your capacitor bank then you rearrange that formula for the capacitance: C = E/(0.5V^2) But you can connect capacitors in parallel and series and that will affect the voltage rating of your capacitor bank (the V). So I don't have all the answers but hopefully some of the above is a good approach.

@@RimstarOrg Thank you very much for the detailed response! I'll have to play around with the math a bit; my main concern was safety and making sure the more powerful voltage from the bug zapper wouldn't somehow blow up my capacitors when I charge them, but the equations you provided are very helpful!

Really it's a question of what's the voltage from your zapper to the capacitors when charging them and what's the voltage rating of your capacitor bank. The voltage rating of the individual capacitors is written on each capacitor. The voltage rating of your capacitor bank depends on how you connect them together: in series or in parallel. Look up how to calculate the voltage of capacitors in series and in parallel for that. As for the voltage during charging, the only way I know to find that is to measure it.

@@RimstarOrg Thank you very much! I appreciate how you take the time to help your viewers!

On an electrolytic capacitor, the side with the stripe is the negative, at least in every one I've seen.

Thanks! Higher capacitance doesn't necessarily mean higher energy. Voltage plays a part too. The formulas for the energy of a capacitor is 0.5 x capacitance x voltage x voltage So for mine, that's 0.5 x 0.0006F x 100V x 100V = 3 Joules For yours, that's 0.5 x 500F x ?V x ?V = ? Joules Fill in the voltage which you'll be using, keeping in mind that your capacitors have a voltage rating, then you'll see how your's compares in terms of energy. That's energy, not force. But it'll give you some idea. Let me know the result -- I'd be interested to know.

RimstarOrg thx. Mine is rated 500 F 2.7 V . Will let u know the result. 😃 Finger-crossed....

That's a lot of stored energy. I would suggest starting at 0.1V and working your way up. Be very careful. I wore goggles when working with mine in case the coiled wires exploded in my face.

Supercapacitors are NOT well suited to this purpose. Photoflash caps are used because they can discharge literally in a flash without damage. Although supercaps can discharge quicker than say, a battery, with any practical coil they would still take several seconds as opposed to the microseconds needed.

Good idea. Though I hesitate in case for some reason someone charges it up and decide not to fire it. It would at least be a good experiment to disconnect it and see the difference in charging speed.

Yeah, I can see the potential danger there, especially if you have kids around. You could always install a small, homemade knife switch across the output to short them out when you are done with the gun. Anyway, I do think it would be worthwhile to experiment with the charge time. I'm sure it will make a difference, but I would enjoy knowing just how much of a difference it would make in this circuit.

I charged it up to only around 100 volts so that the projectile wouldn't be dangerous, but you can go higher for more powerful shots. The total capacitance was around 600 microfarads (see the video at 2:13.

Maybe, maybe. See also coil gun new test: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-TMsLIAmuuO0.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0nMyv83_ycM.html

I say grab 4 car batteries and start connecting wires until something happens or god shows you the answer

The capacitor in this fly swatter is only 154nF, though it is rated for a high enough voltage 400V. So to get 600uF you'd need thousands of them.

RimstarOrg OK.

LOL! How big is the fly? Maybe I should have called the video How to Make a Fly Swatter Less Efficient.

What matters is the total energy in the capacitors. The formula for the energy is 0.5 x capacitance x voltage x voltage. The result is a value in Joules. Connecting more in parallel increases the capacitance and connecting more in series increases the voltage that you can get to without damaging the capacitors. Since the voltage is multiplied twice in the formula, it looks like connecting in series so that you can get to a higher voltage would give you the best results.

It actually depends quite a lot on your coil and projectile too. The aim is to have the magnetic field fall to zero as close to the moment that the projectile makes it to the center of the coil as possible. The amount of time it will take for that to happen depends chiefly upon the inductance of your coil and capacitance of your capacitors. Putting 2 identical caps in series reduces the capacitance to half of one alone but doubles the voltage making the initial pulse more intense but shorter lived so if you have relatively heavy projectiles they wont be accelerated very effectively. Conversely, if you have too much capacitance (or inductance) the pulse will get so spread out that the projectile may accelerate at first but then just get stuck at the center of the coil while the field finishes dying away. The capacitors aren't the only degree of freedom you have though as I've said. You can always wind your coil in sections and experiment with only energizing parts of it or try using a few different coils/projectiles to tune your gun to work with a cap bank config you've decided you like/can live with. The best gun I ever made used a single camera flash cap (220uF or so I think) and for some reason had much better performance firing a pair of steel BB's at a time rather than just one. Fewer turns of coarser wire will have a similar effect to placing more caps in series (faster pulse) and more turns of finer wire has a similar effect to higher capacitance (more drawn out pulse). If your round gets stuck in the coil, try using something a bit heavier or a different shape. I always had good results with BB's/balls. Good luck.

I don't think anyone's succeeded in making one yet. There are some which use lasers to ionize air molecules, but I suspect that's not what you're looking for.

All suggestions I'm considering when I put it in a cordless drill body. I've already come up with and tested a circuit with an indicator light, though I might get one of those small volt meters and embed it in the drill.

You can always just use an existing coil from a shaded pole motor for example. All you have to do is remove the rotor and squeeze the top of the core (where the rotor was) and usually it will buckle and the bottom will spread apart and the coil will come right out. Then just pop the pole out of the coil and away you go. Otherwise just get some plastic bobbins for sewing machines and various sizes of magnet wire and just load them up nice and evenly and experiment. ~28 AWG is good for a small handheld gun. Try to get your coil around 4 ohms.

Amps. Naturally you need voltage too, but the formula uses amps.

@@RimstarOrg I see, but what would be the bottom line or?

I don't understand your question. If you're asking what the lowest current would be, I don't know. It's very hard to measure rapid current like this.

RimstarOrg Sorry about being indecisive with my last question. What I meant to say was: 1) If I need volts, how many would I need at least? 2) And would one volt or a microvolt (I don’t know if I’m using the right terminology) be sufficient enough? Is there also a wiki page I could read off of, if I need to learn more?

You'd need enough voltage to charge up the capacitors. So whatever voltage you'll be charging up the capacitors to, you'll need at least that voltage. In my case my capacitors were rated for around 300 volts. The amount of energy in a capacitor is determined by the formula: energy = 1/2 x capacitance x voltage x voltage So the higher the voltage, the more energy there will be stored in the capacitors. That energy will be turned into the energy in a magnetic field when the capacitors discharge. I didn't want mine to shoot the projectile too dangerously, so by trial and error, I kept mine down to whatever energy there would be when the voltage was around 100 volts. I don't know of any wiki page but you could search google for information about capacitors and how they store energy and how electromagnetic fields work.

The wire I used is insulated with a thin enamel coating, however, I guess you mean wire with thicker plastic insulation. You can use that but you'll either make a bigger coil to get the same number of turns or have fewer turns and a bigger capacitance capacitor bank so that you can get more electrical current. I'm too chicken to make a bigger capacitor bank.

I haven't tried a flashcam charging circuit so I don't know how they compare. I suspect it would work too though.

Increase the amount of energy stored in the capacitors before you discharge them. That can be done by having capacitor which you can charge to a higher voltage -- mine can be charged to 330V but I charged them only to 100V in order to keep the energy low and safer. That can also be done by increasing the capacitance of the capacitors and then charging them to the same voltage but now with more charge.

If you used the same length of wire to the same thickness but over the length of the tube then the turns will be spread apart more and the resulting magnetic field will be weaker. It wouldn't work as well, likely not at all.

@@RimstarOrg But why? The same amount of energy would go into the wire? If the field was dispersed the length of the tube instead of one spot, once the bolt was moving I would expect the bolt to go the same distance? Is it a question of having the power to get the bolt started?

Your last question is the answer. Due to the weaker electromagnetic field, the field isn't strong enough to move the bolt or to move it quickly enough. The formula for the intensity of a magnetic field is (number_of_turns x electric_current) / length_of_coil. You said you wanted to keep the number_of_turns the same but increase the length_of_coil. Notice that we're dividing by the length_of_coil. Whenever you divide by a bigger number, the result is smaller. 1/8 is smaller than 1/2.

@@RimstarOrg Number of turns x current divided by the length of the coil gives the strength of the magnetic field. The energy that is not magnetic field becomes something else like heat? As a kid math would have been a lot more interesting to me had I know I could use it in a practical way to maybe even build a lightning generator. I am thinking of the formula. The extreme would be a straight piece of wire. One experiment a strip of aluminum foil was used as a conductor. When the current was applied the foil moved. Wouldn’t the foil have to push against something?

In answer to your first question, yes, the energy that doesn't go into the magnetic field produces thermal energy, commonly called heat. As for the strip of aluminum foil moving, there are different ways that could happen (high voltage for example) but you'd have to describe the setup more. Was there anything else nearby? How much current? How much voltage?

makin all this stuff

the strength of the magnetic field make it stronger: use more turns on the coil cool the coil (maybe use a superconductor) use bigger capacitors less electric resistance of the projectile higher voltage/more current give more time to accellerate (longer coil) better projectile aerodynamics use explosive projectiles less friction in the barrel

or more caps in parallel

bigger capacitors aka more capacity :p

Shouldn't capacitor is series better? Capacitor in series = higher voltage = faster discharge = faster discharge in one go = more powerful magnetic field?

You wouldn't get that higher voltage unless you let it charge for longer though, plus this halves the capacitance

1. You need some way of knowing when the capacitors have reached the desired voltage or charge level. I also came up with a circuit for having an LED come on but it would have added too much explanation for this video. 2. A few people asked for this one. And I can't stop myself. 3. You can get even more power from a rubber band but then you wouldn't get to do the interesting electronics project. 4. You can do that too. I chose to do it by hand. No reason. 5. The tape makes it easier to wind the next layer. 6. No, I'm not sure the coil is the optimum length go the capacitor's discharge time. It just works.

Capacitive discharges ruin the contacts and may even weld them together, a switch might be better at first but quickly turns into a consumable item. See those sparks when he touches the clip to complete the circuit? They'll still happen but inside the switch. An SCR would be better but I have a feeling OP was trying to keep the part count low.

Yup, I was trying to keep the part count low. I'll look into an SCR for the future though, so thanks to the tip.

Can you describe what you're doing.

Sir I did it with no capacitors and low number of turns , is that necessary to add the capacitors in the circuit sir , is that capacitors is my problem I'll fix it sir

And now I'm your subscriber

Where are you getting your high current from? This requires a large amount of current over a brief amount of time. Storing up a large amount of charge in capacitors and dumping it all at one time provides that.

Welcome.

Of course it's working.

Ok sir thank you

Hahahaha It's actually a prank bro.

@@anthony1003 no, it's work

If you're referring to the tape on the coil, it was to keep each layer fairly flat for the next layer. You can skip it I guess if you're not going for neatness.

What do you mean by negative? Is this a measurement you made or did you see it in the video somewhere?

It is a measurement that I made, My coil gun isn’t working, and I measure inductance of the coil, it was -0.34 H, is it normal that the value is negative ?

That doesn't sound right. But I've never had a meter with an inductance setting so I can't advise you on what you're seeing or what might be wrong with the way you're measuring it.

@@silvanamunoz1941 Inductance can't be negative, there's something wrong with the way you are measuring or with the multimeter or both.

That would be fun! Actually, I have a bunch of cordless drill bodies left over from my search for motors for my BB-8 droid so I want to put it in one of those.

Already done. See this video and the rest of the videos in the playlist ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vemF7p0cbHU.html. Enjoy!

You could just charge up to a higher voltage but I don't know at what point that would start breaking things. It at least would need a diode as suggested by others in the comments. I am thinking about a more powerful one, but I probably won't do a full how-to-make video since it's not this channel's style to encourage anything too dangerous. A lot of young students make things seen here.

Thanks! If you mean the error in the video description, I just now fixed it. The change may take a while to propagate thoughout the network but it's working for me now. Thanks for letting me know!

Your mom

I'm not crazy about it either since I have young viewers who make the things I show, which is why I made it fairly low power. Plus, with one minute between firings, people will look elsewhere if they seriously want one. I will be doing one in a drill body but I'm on the fence about making it faster-charging.

Thanks!