Introduction: Capacitor Charger/Coilgun V2.0

Ok. I know that there is already an instructable on how to build a capacitor bank charger, but for those of you who are either looking for more inspiration, or just want to see a different way to make it, check here. This version made is more of a ~much~ more deluxe version. Why did I make this? Well, I was going to use it for a coilgun, until I realized that the idea of being able to shoot something at at least 300fps is not plausible, unless you have a more powerful circuit (and therefore more powerful cap. bank). I am a bit new to this electronics stuff, so if any of you out there have some know-how to contradict this, and if it really IS plausible, please, prove me wrong! Please note, though, that this device has a very high output voltage, and it (might?) kill the weak of heart if an arc occurs across their heart (not to mention, it HURTS), so be careful when handling any capacitors and/or the circuit connected to them. Lastly, Please excuse me for any errors there may be in this instructable; it is my first. Enjoy!

6-21-07 UPDATE: Added an SCR into the circuit (new button; the old one short-circuited). Details on the SCR on step 3.

Step 1: Enter at Your Own Risk!

EDIT: Make a more robust coilgun! Use this guide as a supplemental reference, but you probably don't want to use it as a standalone walkthrough. This is a wonderful starting point but some things have been misengineered (made up my own word...).

Looking back on this instructable, I realize there are numerous fatal flaws in the design. Some recommendations:

-A more stable (and much faster and effective) CHARGER

-At the current time, I'm pretty sure the SCR in this design will, *ahem*, explode the way it is implemented. One with higher voltage/current abs. max ratings is necessary, or you can use a technique called "Paralleling, Anode to Anode, Gate to Gate, and Cathode to Cathode" (I'm quoting an excellent site for coilgun reference HERE ). Pardon my engineering but I think it was about 15 when I did this instructable.

Good luck and have fun!

Step 2: Parts List


-project box or some other sort of enclosure (I used a RadioShack one)
-disposable cameras; the more, the better (in this case, 14 of them)
-1.7V volt or VERY low consumption LED (I used a RadioShack 1.7V red LED)
-binding posts (those screw-down thingies on the outside of the box) RadioShack catalog #274-661 or equivalent (you will need 4)
-2x on/off switches (I used what I had; PCB (PC Board) ones.
-some wire (In this case, I used 22 guage, but I think you can use a lower guage even though there will be high voltage/current; it's only split-second bursts)
-batteries and holders (maximum 6V)
-large on/of rocker switch (optional for protection)

-soldering iron & solder (you CANNOT just wrap the connections; they need to be permanent and well-connected for this project)
-electrical tape (masking tape WILL NOT suffice)
-wire cutters
-Drill and Proper Bits

Step 3: Make/Connect the Capacitor Bank

This is simple. Take all the disposable cameras you got, and (carefully) discharge the two leads coming from each capacitor on the chips (if you have not already done so). BE CAREFUL. If you touch these leads, you will get a nasty shock. after that, cut the capacitors off the boards, making sure to leave as much of their leads on them (it will make soldering them together easier. Then line them up so that there are two rows of five caps, with the striped sides (-) facing in one direction (in this case, they are all facing towards the bottom right-hand corner of this photo). Then solder them together (- to - to - to - and + to + to + to +, and so on and so forth). My original design was just four of the caps on a bread board, and that's why there is a bread board in this project. I was just too lazy to take the caps off and solder them on to the other bank, so you can just add them to the bank, and not bother with a breadboard. Now after all this, solder the array to the directions of the schematic, but BE SURE to solder them with proper polarity, or they WILL explode!

Step 4: Build and Enjoy!

I am sorry I am unable to list multiple steps and pictures with each step, but I finished this project before I discovered If you have questions, feel free to ask me any questions you may have! Refer to the mock schematic for reference (Note: you will have to get the higher-res one to see the words. Click on the little I at the top left-hand corner of the picture, and then at the next page, click on the link at the bottom-left hand corner of the picture). Most importantly, DO NOT cross the wires on this schematic. I know it looks like they cross at certain points, but ignore that. Failure to heed this warning may lead to a burnt out circuit, blown capacitors, or a number of other [bad] things. Another note: once you have assembled this, you can add additional capacitors to the circuit (just wire them to the external charging jacks), and they will add to the power of the internal ones, like I did with my massive, blue Nippon Chemi-Con's.

6-21-07 UPDATE: Below is the SCR (Silicon-Controlled Rectifier) that I salvaged from a light dimmer (model no. Q2008LT). Basically what it does is, it triggers the capacitors to discharge when it receives a small pulse of electricity above ~.5V. This way, the only electricity going into the switch is just as low as the power source you use to trigger the SCR. You can find SCR's in certain electronics, or you can order one online for less then 50 cents, BUT BE SURE NOT TO CONFUSE SCR'S AND VOLTAGE REGULATORS (and triacs); THEY BOTH DO TOTALLY DIFFERENT THINGS, BUT THEY LOOK EXACTLY ALIKE!! Also, don't worry about the middle pin; we won't be using it.
Using the circuit I provided will, unfortunately, ruin your switch and make the coilgun inefficient. But by using the new setup with the SCR, it will work much more efficiently. Be sure to take a look at the schematic (the 2nd one)!
NOTE: Elaborate on the diagram; I have not updated it to reflect the added components.

6-24-07 UPDATE: DO NOT USE THE SPECIFIED MODEL OF SCR; IT IS ACTUALLY A TRIAC (different kind of device; looks the same). Try using one of the SCR's on THIS page.

Step 5: The Finished Product!

Hers are the guts! When you want to use it, just connect about 3 volts to the power binding posts, make sure the charging switch is set to "on", and wait until the light is solid. Then push the discharge button to release the charge out through the prongs. The thing is, the light is does not indicate a FULL charge. Use a mutimeter to check the power coming out of the capacitors as they charge, but be careful. They are fully charged when the meter stops at ~320V, and it should not be too different for you, depending on what camera circuit you are using; these circuits usually charge the caps to around 300-330V. When you get the highest reading, remember the charge time.

6-21-07 UPDATE: The first picture is the new, revised coilgun.

Step 6: Some Tips

-On the (mock) schematic, DO NOT actually cross the circuit at places where it SEEMS you should make the connections
-Keep the flash in; I do not know why, but when I removed the flash, the caps did not charge. I tried removing the flash AND bridging its connections, and it still did not work. Just leave it in. If you figure out this odd ghost in the machine, let me know.
-When you extend the indicator light to the outside of your enclosure, you don't need to buy and LED IF (and ONLY if) the chip already has one. I would not recommend trying to fuss with a glass neon bulb. They can break.
-You can add a safety switch, which would be in line with the power in wires (and keep it on the inside of the box), so if you don't want anyone messing with it, or just for safety reasons, you can turn it off, so even if someone connects power, nothing will charge.
-MAKE SURE you connect the capacitors properly. If you don't, they WILL explode. Also, be sure o connect the in PARALLEL, not series (Parallel is + to + to + to + and - to - to - to -; so on and so forth. Series is + to - to + to -; so on and so forth). If you do not do this, they will not charge sufficiently.