Coilgun

[x88x]

Yes, the project that has gotten me more weird looks at work than when I told them I was going to an anime convention, my coilgun project is finally officially starting. :D

I've been dabbling around with figuring out some stuff for a while, and I decided it was finally time to start a worklog.

First off, for anyone not familiar with the concept, a coilgun (http://en.wikipedia.org/wiki/Coil_gun) is simply a linear magnetic accelerator. In the simplest system, a single-stage coilgun, a ferrous projectile is loaded in place into a barrel/trough/whatever behind an electromagnetic coil. Current is then passed through the coil, generating a magnetic field, which pulls the projectile towards the center of the field (ie, the center of the coil). Ideally, the current should then be cut off exactly as the projectile reaches the center of the field, thus transferring as much energy to the projectile as possible. Generally, however, the field is active for such a short time that it does not matter (the reason for this will be discussed later). A more advanced version of a coilgun is the multi-stage design, which uses multiple coils in series, each accelerating the projectile further.

For anyone who is confused or couldn't be bothered to read all that, here's a great animation showing a multi-stage coilgun in action (thanks wikipedia!).
http://i428.photobucket.com/albums/qq3/x13931x/Coilgun_animation.gif

A high voltage must be passed through each coil in order to generate the required magnetic field. This is normally achieved by using a bank of capacitors to build up a large charge over a (relatively) long period of time from a much lower voltage power source. The capacitor bank is then discharged instantaneously (or near enough as makes no difference) through the coil, creating the magnetic field.

I started off winding some coils for testing. Both are 1.25" long, but one is 4 layers of 12AWG magnet wire, and the other is 4 layers of 18AWG magnet wire. For anyone unfamiliar with magnet wire, it is simply a single, solid strand of copper coated with a thin layer of enamel. This makes it ideal for winding electromagnet coils (thus the name), because it allows the space between each strand to be almost negligible. This is important for some lovely equations I'll probably go into later, but suffice it to say for now that it lets you get a stronger, more compact coil, using less wire.

http://i428.photobucket.com/albums/qq3/x13931x/coilTests_01.jpg

There are many different coilgun designs floating around the internets, but they generally cost obscene amounts of money to create, or are based solely on the capacitors and charging circuits out of disposable cameras. Now, this is all well and good, especially if you can get them for free, but through some Electronics Goldmine (http://www.goldmine-elec.com/) surprise boxes, I came into a crapton of 330uF 35V caps, which I'll be using for this.

This also puts me in the position of needing to make my own charging circuit, but from my reading around, the charging circuits out of disposable cameras tend to be rather...s***. They work well for a while, but if you use them too much or try and pull too much out of them, they tend to, well, fry. So, after much searching, I finally found information on building a cap [bank] charging circuit, which actually turns out to be remarkably simple. I found a schematic by one rwilsford07 in this instructable (http://www.instructables.com/id/DC-DC-HV-Boost-Converter/), interestingly enough developed for the same reason. This was great, but it took a bit more talking with a couple EE friends to learn exactly what was going on with the inductor.

So, class time again. ;) (The guy who wrote the instructable I linked above has a very in depth explanation of his circuit there, but I'll give the lite version.)

We start off with the circuit like so (current follows the red arrows), with the transistor conducting.
http://i428.photobucket.com/albums/qq3/x13931x/F88HBD2FP9CSW2G.jpg
Disclaimer: This and the next image I'm mirroring from Intructables to save their bandwidth from cross-embedding. They were created by the same guy again, not me.

In this state the power source is feeding into the inductor (the thingy at the top), creating a magnetic field to store the power. The path of least resistance is across the closed transistor, forming a simple loop and not touching the cap at all. The transistor is then switched off:
http://i428.photobucket.com/albums/qq3/x13931x/FQ8O3KKFQCTKS8F.jpg

In this state the power stored in the inductor is dumped into the cap.

The signal coming from off-screen left is a square-wavesignal from a 555 timer IC (http://en.wikipedia.org/wiki/555_timer). The result of this is that transistor is turned on and off very quickly, speeding the charge of the capacitor(s).

Like I said, a 555 timer was used in the original design, but I don't have any right now so I'm gonna be testing different timings with a microcontroller I have to see if there's any difference. I'll probably end up just putting a 555, but I have the capability and I'm curious. :P

The problem I ran into that some of my EE friends cleared up was whether the inductance of the inductor (http://en.wikipedia.org/wiki/Inductor) mattered at all, but it turns out that, well, it doesn't. Think of it like the battery is a hose filling up a bucket (inductor), that is then used to fill up a swimming pool (capacitor(s)). No matter what size bucket you use, you'll fill up the pool eventually. You just might fill it up a bit faster with a larger bucket.

So, knowing all this, I threw together a quick circuit to test the design, substituting a manual button for the 555 timer and transistor just because I wanted to see what exactly is going on. Also, I was too lazy to bother with the uC.. :whistler: It works quite well, though slowly since I'm manually initiating each stage...but it works, and that's what's important. :D
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_02.jpg

I'm gonna try this circuit with a few different inductors I have lying around, see what the difference is, but I'm not really hugely concerned about the charging speed right now.


Hopefully I'll be working on this more regularly now, but no promises...my summer is turning out to be a lot busier than it was supposed to be. :(

On a side note, does anyone know where I can find mechanical meter gauges inexpensively? I want to have a mechanical gauge for each capacitor bank, but everywhere I look they're really expensive. I want each to have a range of from 0V to 1kV, which doesn't help... :whistler:

[Oneslowz28]

Subscribed!

There is a pretty good video that describes inductors on youtube. It's titled "Make Presents The Inductor"

[x88x]

Thanks. Here it is for anyone interested. It's a good explanation of the theory behind inductors, and the affect they have on electrical signals.
http://www.youtube.com/watch?v=STDlCdZnIsw

[x88x]

Well, I spent about a bit tonight relearning how transistors work. ...yeah, I kinda slept through most of my circuits course. <_< >_> Somehow I managed to ace all the labs though. *shrugs*

Anyways, once I figured out what I was doing, I threw this circuit together to get the manual switch removed another level from it. ..still too lazy to mess with the uC...yeah...I'll get on that tomorrow. Right..tomorrow..

Right, so, here's the charging circuit now, with my multimeter showing the voltage across the capacitor to show you it is actually working. It drops off pretty fast when I stop charging it, but I'd say charging to 18V off a 3V source in about 5 seconds of my manual switching is pretty good. It takes probably about 10 seconds at a switching rate of ~3-4Hz to get up to 20V, but then takes probably at least another 10 seconds to get up to 30V. I hooked up two caps in series to see how high I could get it before I got sick of pressing the button.. I got up to about 36V after maybe 30-35 seconds, but by that point it had almost slowed down to ~0.05V/s, so I decided to stop. I'll get the uC hooked up tomorrow and see what I can do about getting some real timings.

http://i428.photobucket.com/albums/qq3/x13931x/coilTests_03.jpg

Some of you may notice that the inductor changed. I mentioned that I was gonna try throwing some of my other inductors at it? Yeah...this one works almost twice as fast as the other one. O_O I did not expect that. Especially since according to my calculations the first one should have a higher inductance value. Though, come to think of it, the equation I was using didn't factor in multiple layers, which the first one had, so my value for that one is probably wrong.. If my math is right, and it always is ( ;) eh? eh? anyone?), this inductor should have a value of 148.7mH. I'll probably end up digging up or finding a nice ferrite core and winding my own, especially once I'm charging a 700V capacitor bank.. Ah well, this one works for now.

[Oneslowz28]

I have a crapload of small inductors. If you nail down the h you need I might have one.

[x88x]

Well, I realized I was using the wrong formula for finding the inductance of the second inductor as well, what with it being a toroid and all... :whistler: So, using proper equations for both, it turns out the first was a 124mH inductor, and the second is a 234mH. I also checked on the manufacturer stats on the inductor that the guy who did the ible I linked used, and his is a 390mH.

I have some PCBs that I've been meaning to tear apart, and a few of them have nice big toroidal inductors on them...we'll see how they work. :twisted:

[x88x]

So, no work on this directly tonight, but after burning out one of my alligator-clip jumpers a while back, I decided I needed some a little more...robust. :twisted:

So, today I stopped at Harbor Freight and picked up a set of clips of various sizes, and I found this on sale. At $50, I wouldn't have gotten it, but for $30? Yeah, I think that's worth it.
17' 10AWG
20' 12AWG
22' 14AWG
39' 16AWG
86' 18AWG
124' 20AWG
64' 22AWG
All twisted copper single-conductor.
Plus:
30' copper/alu 2-conductor speaker cable
20' of something they call 'zip cord', which appears to be two 18AWG twisted copper conductors running parellel
20' of something they call 'bell wire', which appears to be two 22AWG solid copper conductors both individually insulated and inside an insulating sheath
Plus, it came with the nice rack. :D
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_05.jpg

So, putting those together I made myself some better jumpers.
On the outside we have two lines (red) with pretty big clips joined by 10AWG wire (no stamped current rating, but I'm guessing it's pretty high). Going in, we have a single line (brown) joining two 5A rated clips with 14AWG wire. Unfortunately, the set only came with the two clips, not 4, so I only have one line that size. Also, I didn't actually notice the 12AWG spool until I was typing it out above, which is why that line is 14 instead of 12. Then, on the inside we have four lines (blue) with two different size standard alligator clips (two lines with each size) joined by 18AWG wire.
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_04.jpg

There was another type of clip in the set that I can't for the life of me figure out how to connect. Any ideas?
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_07.png

[x88x]

Well, I figured out the attachment style for those clips, so now I have two more ~2.5' 14AWG jumpers (12AWG wouldn't quite fit around the screws correctly :( ).

I also ran across two websites that some might find interesting.

A listing of a bunch of different coilgun projects.
http://www.coilgun.ru/

A site that has a lot of information about coilgun design, getting into much more detail than any other source I've found.
http://www.coilgun.info/about/home.htm

[x88x]

Not much today, but I did get some done. I decided to attack the inductor problem first. Unfortunately, even they're big and intimidating, the inductors I pulled off the Plasma PCB, they weren't actually very...inductive... :P Even the big one next to the board in the picture is only a 134mH inductor. So instead I took apart one of the smaller toroid inductors from the board and re-wound it with a single layer of 30AWG magnet wire. And no, I'm not gonna count those windings to figure out the inductance.. -_^
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_08.jpg

After making it, I didn't really expect it to work that well, tbh, but once I hooked it up, the change was pretty impressive. With the 234mH coil I had been using before, it took 9.3s to go from 2.5V (base voltage). With this one, it only takes 6.4s. I'm considering breaking this one down too and rewinding it with several more layers, just for the hell of it. ...the only problem is that it took about an hour to wind the first layer... -_^ Hmmm, or maybe I could just wind more layers on top of the first...I'm sure I could find a use for a smaller, secondary inductor. :twisted:

[Bopher]

If my math is right, and it always is ( ;) eh? eh? anyone?)

Tony Stark:banana:
Now get to work on the ARC reactor that will power this thing:twisted:

[x88x]

Yes! Well, at least somebody got it. ;)

Along those lines, the Arc Reactor has always bothered me...it's just too convenient. (Yeah, yeah, I know...)

So, I got the charging circuit better assembled now...and ran into a few problems. First off, I accidentally blew out an I/O pin on my uC before I thought to use a diode instead of just hooking it straight in.... :facepalm: ..yeah, that's fixed now...feel free to ridicule. :banghead: The second thing I ran into was rather unexpected...

Once I had a good switching rate (10 5Hz atm), I realized that the charge rate is waaaaaay faster than I was expecting from previous tests (100V in 1.9s!), so I needed to start playing with higher voltages to continue testing the circuit. So, I pulled out one of my 3uF 450V caps and let it run. ...now, the thing is, I neglected to check the limits of the transistor I was using before I did that, so I was rather perplexed when it stopped charging at 100V. ...and then ceased to work at all.. :facepalm: I checked the datasheet again, and it's actually 60V, not 100. :eek: So no wonder it burned out.

So, into the parts bin to find a higher rated transistor! Hurray for plasma TV parts! :D

Here's a shot of the circuit as it is now. Yes, I am being semi-safe and using fairly hefty jumpers and a 0.01Ohm 10W resistor to drain the caps when I'm done with them. Another benefit of the tiny capacitance of the cap I'm using is that it drains really fast by itself, so even when I had it up to 100V, by the time I had shut off the power and reached over for the jumper, it was down to ~35V.
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_10.jpg

[x88x]

Hmm, so, I think I'm missing something..

I have a nice little 600V 45A IGBT, and I was thinking that I should just be able to drop it in where I had the NPN transistor...but that's not working... It's not that it needs a higher voltage across the Base-Emitter lines to switch, because I tested it with the 2xAA's, and it switched just fine (I'm running this circuit on 5V atm). IDK, like I said, I'm guessing I'm just missing something about using IGBTs, since, well, I've never used one before. :P Anyways, it's late, I'm tired, I'm gonna go to bed now.

If anyone's interested:
the transistor I had been using:
http://docs.google.com/viewer?a=v&q=cache:SSn9lYMRQJcJ:www.fairchildsemi.com/ds/TI/TIP110.pdf+TIP110&hl=en&gl=us&pid=bl&srcid=ADGEESgRZDXhm-jb5t4U357vo1wnET1xWRepPucWqwD_6PLqXLzeir9sMhV_EoU-mf8lETNOi7W5o-I7WO0ruhu7xxWwItxx3tS8mRJeMGtbckNi4p0_gMuLqmyvJtmt jB3RZsgKePEA&sig=AHIEtbSkgAdoFhncYZD0uZqBOaOQ3I-4vA
the IGBT I want to use:
http://docs.google.com/viewer?a=v&q=cache:SFn19oc_QwAJ:www.datasheetcatalog.org/datasheet/fairchild/HGTP20N60C3.pdf+20N60C3&hl=en&gl=us&pid=bl&srcid=ADGEESi7Z_SHkSYfxBSdcYGGUZ1iTaNtLT3SmRnI-x0lG-Zy_jkeb1AohpJBNYYwuOzmGsdbEshRxXTs7Qvd2V-scAZVdulcmfXUxozB4nveT2F-wjCNUppVuKJPSopdFMWLvCgFrrd2&sig=AHIEtbSRITNiEr0k10xYrYZ-CWjdQSppgg

[x88x]

Heeheeheehee!!! I had a great moment just now where I finally worked out the last kink in my charging circuit and it suddenly worked and worked AWESOME! :D

Ok, let's see, what did I do today...

Ah, right, IGBTs. ..yeah, #&%@ IGBTs. :mad: Ok, so maybe not; they'll be great for switching the acceleration coils...not so much for a charging circuit though. The one I was trying to use has a switching frequency of something like 1/7-1/8Hz....yeah...not so much with the working...ness.... -_^ Needless to say, when I figured that out I was pretty pissed that I had wasted so much time trying to get it to work.. On the other hand, now I know how IGBTs work, so it wasn't a complete loss.

Instead, I pulled out one of the transistors I had bought with switching the coils in mind, but knowing what I do now, there's no way on earth these transistors could handle the current levels that's gonna require. These transistors are 1500V max, 8A max (not both at the same time, but that shouldn't be a problem..I think they top out at 700V when at 8A.. datasheet (http://docs.google.com/viewer?a=v&q=cache:L7RJ_83LiJQJ:www.st.com/stonline/books/pdf/docs/4491.pdf+BU208A&hl=en&gl=us&pid=bl&srcid=ADGEESilbEIcXGnnVgE4kljAIWYDFTfeNGywm1pFrhHE kkhoVXzTGVi3i6w6htoWlr4YGdsPRgT1uctzqTfKh48gn6NuUh-nysB1z2fQgazu77I75zdLCDSDvd0VqokefVV7ZzN8F52R&sig=AHIEtbRMbBEKcI3gT-tDrFSftwKzUREkaA) if anyone's interested), so they should work marvelously for any capacitor bank I anticipate charging any time in the near future.

And indeed, it worked out great! ...once I figured out that the first one I was using was DOA.. :facepalm:

...ok, so maybe it might have also had something to do with me hooking it up wrong and possibly frying it...but I'm gonna go with DOA. ..yeah.. :whistler:

So, long story short, I finally had a circuit that wouldn't blow up at random intervals, so I decided to see what this thing could do. :twisted:

....and promptly ran into a 100V ceiling :banghead:

Now, after switching out different caps, waiting a long time for them to charge, that not fixing the problem, and being on the verge of swapping out inductors to try and find the problem, I started thinking.. Yes, yes, I know, shut up. :P When I changed the switching frequency from ~3Hz using a manual switch to 5Hz (I miscalculated in a previous post: 100ms on, 100ms off == 5Hz, not 10Hz) using the uC, I noticed a quite large improvement in charging times. So, since I basically just pulled 5Hz out of nowhere because 100 is a nice round number, I decided to start experimenting with that instead. Now, instead of trying different frequencies at random, I decided to go back to that instructible that that I linked in my first post, and see what frequency he used. After checking his circuit diagram:
http://i428.photobucket.com/albums/qq3/x13931x/F9EHQX2FWA98MCI.jpg
(again, mirrored to save Instructible's bandwidth)

...and spending some time with our great lord and master the almighty Wikipedia may it live forever, to figure out how to figure out the frequency (http://en.wikipedia.org/wiki/555_timer#Astable_mode)..

I figured out that his circuit has a switching frequency of about... 3.1kHz. :eek: ..yeah, I was waaaay off.

So, since I wasn't quite sure what would happen if I put decimals in the Arduino 'delay' function, and I couldn't be bothered to find out, I tried 1 instead. Rather, now I have it generating a square wave 1ms on, 1ms off, working out to only 500Hz, but still way faster than I had been doing. Ok, typing that made me curious, and as it turns out, you can put decimals in the 'delay' function. :D So, I have it set to 0.15 now, which results in a 3kHz frequency.

..what? Oh, right, the point of that. ..it's late...

Right, so with this new crazy fast switching frequency (and even the 500Hz I had when I started writing this post), the charge rate is INSANE! Seriously, with the little 3uF cap it takes 2.5s to get to 450V! :D :D :twisted:

If it can do that now, just imagine how fast it'll charge stuff once I upgrade that inductor. :twisted: *cue evil laugh here*

So, the circuit as it is now:
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_11.jpg
You like my TT blast shield? ;) Finally, that stupid V9 was useful for something. :P

..ok, that's not fair...it has been being a wonderful bedside laptop stand...

And, on that note, I'm gonna head to bed. Hopefully tomorrow later today I'll be able to actually get up at a reasonable hour.

[mDust]

Haha! The excited tone (that I inferred) of the posts to the trial and error methodology to the evil laughter...I love it! Keep up the excellent work and you'll be a mad scientist in no time...

[x88x]

Heheh, thanks. Yeah, that definitely is an excited tone you're inferring. :D ..also, all of these posts have been finished around 2-3am, so I wasn't exactly in a well-rested state of mind...which probably contributed to the, shall we say, unusual..tone.

[Oneslowz28]

That charging rate is insane! I can not wait to see the work on the bank and then see some projectiles hurling through the air at near warp speeds....!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[x88x]

Ok, some updates on this. I went ahead and added some good contacts on the inductor I'm using right now, so it's not a pain to actually swap in and out of the circuit.
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_12.jpg

So, that makes things easier for now, but as I mentioned before, I'm going to be replacing it. On that note, I unwound the giant inductor I pulled off the TV...for now it's empty, but I have 100' of 24AWG magnet wire on order that I'll be rewinding it with.
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_13.jpg

I also threw together a quick testing circuit to test the discharge into a coil. Good news, it definitely worked, so no worries there. :D
http://i428.photobucket.com/albums/qq3/x13931x/coilTests_14.jpg

Now to work on building a good cap bank and making a switching method for coil discharge. Right now I loose a lot of charge through the simple little wire switch. :P


On another note, OneSlowz28, crenn, and I were talking on Saturday, and crenn suggested a reason why the transistor overloaded. It made sense then, but I just thought about it again, and I think you were wrong. ..or I could be wrong again, idk. :P

What I'm thinking is the problem now is this:

When the transistor is conducting, the path of least resistance follows:
power supply -> inductor -> conducted through transistor -> power supply

Then, when the transistor is non-conducting, the circuit cuts to:
power supply -> inductor -> diode -> capacitor -> power supply

In this state, there is the constant possibility of the current passing through the transistor instead of the PSU and inductor, if the resistance of the transistor becomes less than the resistance of the PSU and inductor. Normally this will never be the case, however the 60V limit on the transistor determines the max voltage that can be kept from conducting between the collector and the emitter (iirc). So when the voltage in the capacitor passes 60V, the circuit breaks down into two parts.
Capacitor circuit:
capacitor -> burned out transistor -> diode -> capacitor
PSU circuit:
PSU -> inductor -> burned out transistor -> PSU

Like I said, I could definitely be wrong again, but this explanation makes the most sense to me so far, considering that the diode has never fried.

[crenn]

Well, I've been looking into it with the circuit simulator that Oneslowz28 linked us to. I think I'm partially right... but I don't know why yet!

This is the code for the circuit I set up:

$ 1 4.9999999999999996E-6 0.028650479686019012 43 5.0 50
t 336 320 384 320 0 1 -0.9084951952828586 0.15636575820549847 1000.0
R 256 256 256 240 0 2 3100.0 2.5 2.5 0.0 0.5
v 192 384 192 320 0 0 40.0 5.0 0.0 0.0 0.5
l 272 144 384 144 0 0.148 0.09018997524958472
d 384 144 464 144 1 1.1
w 192 192 192 144 0
w 192 144 272 144 0
w 384 336 384 384 0
w 384 384 192 384 0
w 256 320 336 320 0
w 464 384 384 384 0
r 576 144 576 384 0 1.0
s 464 144 576 144 0 1 false
w 576 384 464 384 0
s 256 320 256 256 0 0 false
s 192 320 192 192 0 0 false
c 464 208 464 320 2 0.0033 0.046955623951132175
w 464 208 464 144 0
w 464 320 464 384 0
w 272 112 384 112 0
r 272 80 384 80 0 1.0
w 384 304 384 144 0
o 16 64 0 35 0.15625 0.4 0 -1
o 18 64 0 35 5.0 0.4 1 -1


And the link to the simulator:
http://www.falstad.com/circuit/

Interesting things I noted: If you place just a wire where the inductor is, the circuit still works... but the voltage on the capacitor, when you turn it on, is pretty much instantly at the 'stable' final level, which means it's drawing a lot of current at that moment. Changing the inductor to a resistor has the interesting result of the capacitor not getting much higher than a value around 4.5v.

Another interesting I noticed that it seems you can do the circuit without the transistor, it slightly slows down the charging process, but not by much and it's probably safer to have it in to help regulate the amount of current drawn.

The other intesting thing was I couldn't get higher than 8.43v. There are things I still don't quite understand, but I don't think I'm fully wrong yet. I'm curious to what you think. The simulation currently is semi supporting my theory, although probably on 'ideal' conditions.

[SXRguyinMA]

that circuit simulator is awesome! now if only there was a way to interface that with arduino :D

[x88x]

Ok, I took a look at the simulator and it's doing things correctly. When you have the wire or resistor there, it goes immediately to almost the voltage of the power supply. That's because you're basically just hooking the cap in parallel with the power supply. The resistor will block more voltage than the wire (you know, it being a resistor and all ;) ), so that's why it goes to a lower voltage.

The reason you're maxing out at 8.43V, and why it takes so long for it to get there, is because you set the cap to 3.3mF, not 3.3uF. 3.3mF is massive. Also, 134mH is pretty small. I think the one I'm working with is around 900mH, if my estimates of the number of coil windings is correct....actually, it's topping out at 8.14V now with 3.3uF and 900mH...hmmm :think: IDK, here's the simulator code for my circuit with the small testing cap. IDK why the simulator is capping it there, but I promise it works irl. :P


$ 1 4.9999999999999996E-6 0.7703437568215379 43 5.0 50
t 240 320 288 320 0 1 -4.225879159308766 0.15544009054704944 1000.0
R 160 256 160 240 0 2 3000.0 5.0 5.0 0.0 0.5
v 96 384 96 320 0 0 40.0 5.0 0.0 0.0 0.5
l 176 144 288 144 0 0.9 5.010000069016896E-11
d 288 144 368 144 1 1.1
w 96 192 96 144 0
w 96 144 176 144 0
w 288 336 288 384 0
w 288 384 96 384 0
w 368 384 288 384 0
r 480 144 480 384 0 260000.0
s 368 144 480 144 0 1 false
w 480 384 368 384 0
s 160 320 160 256 0 0 false
s 96 320 96 192 0 0 false
c 368 208 368 320 2 3.0E-6 7.917887980984668
w 368 208 368 144 0
w 368 320 368 384 0
w 176 48 288 48 0
r 192 80 304 80 0 1.0
w 288 304 288 144 0
d 160 320 240 320 1 0.805904783
o 15 64 0 35 20.0 0.05 0 -1

[crenn]

Ok, I took a look at the simulator and it's doing things correctly. When you have the wire or resistor there, it goes immediately to almost the voltage of the power supply. That's because you're basically just hooking the cap in parallel with the power supply. The resistor will block more voltage than the wire (you know, it being a resistor and all ;) ), so that's why it goes to a lower voltage.

The reason you're maxing out at 8.43V, and why it takes so long for it to get there, is because you set the cap to 3.3mF, not 3.3uF. 3.3mF is massive. Also, 134mH is pretty small. I think the one I'm working with is around 900mH, if my estimates of the number of coil windings is correct....actually, it's topping out at 8.14V now with 3.3uF and 900mH...hmmm :think: IDK, here's the simulator code for my circuit with the small testing cap. IDK why the simulator is capping it there, but I promise it works irl. :P
<Code clip>

Interesting, I could have sworn at one stage I had it with the wire making it go upto 7v or so. Regardless, the similator is now showing the right values (I didn't know all of your components, and as for the 3300uF capacitor.... whoops ^-^; ) and appears to be semi accurate.

Regardless, I doubt the simulator is showing exactly real world but certainly shows things working (not exactly, but anyway)! And I don't doubt it works in real life!