Make a Cheap Disposable Camera Capacitor Bank




About: Me on YouTube
This instructable will show you have to make a simple capacitor bank and charger out of old disposable cameras that you can get for free at your local store.

You can then use it for powering things such as coil guns or just blowing things up! See the second picture above? that was the spark created when I discharged such a capacitor bank. It was also very loud too!

The video below is the bank being discharged through various items including thin wire, transistors, resistors and headphone drivers of all things.

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Step 1: Parts List

You will need a few items to make this.

A few disposable cameras. You can get these from places like Tesco and Walmart for free, all you have to do is ask at the kiosk where they develop camera film and they will usually give you a bag full of disposable cameras for free! I once got given 20 of these at Tesco.

Wire. This is needed for connecting things up.

Veroboard/strip-board. You don't HAVE to use this but it helps when it comes to soldering and makes it look neater.

Solder+soldering iron. For soldering electrical connections of-course!

Electrical tape. Not essential, but useful for holding things in place and covering exposed high voltage electrical connections.

Terminal block. For connecting a discharge stick to the capacitor bank. Because of the high peak currents flowing, alligator clips are not suitable and will just spark becuase they just don't make good high current ultra-low resistance connections. You can however use them for connecting the charger to the bank or connecting the battery/power supply.

Also you could just use solder, I used the terminal block so I could easily pack the bank away.

Tools. A metal screw driver with an insulated handle.

I am in no way responsible if you mess up with this circuit. If you mess up, receive an electrical shock or burn your house down whilst making this circuit you have no-one to blame but yourself. By following this guide in order to make this circuit you agree to accepting all liability if something were to go wrong.

I will answer and try to help with any questions you have via the comments.

Step 2: Safety/disclaimer

Please take a minute to read all of the safety pointers listed here...
  • NEVER touch the output wires or let anyone (including pets) come in contact with the wires. Doing so WILL result in serious injury or worse...
  • ALWAYS keep the bank shorted out when not in use (that means connecting negative and positive together so no charge can be accumulated). Also remove the battery/power supply from the charger when not in use.
  • Only build this if you are confident in electronics and high voltage.

  • Capacitors out of disposable cameras are going to be very cheap in build quality and are not intended for long term use. So do not use this bank in a critical application.
  • If one capacitor goes bad then there is a chance of it exploding with all of the energy of others being discharged into the bad one.
  • Use safety goggles or a protective barrier of some sort when creating sparks.

I am in no way responsible if you mess up with this circuit. If you mess up, receive an electrical shock or burn your house down whilst making this circuit you have no-one to blame but yourself. By following this guide in order to make this circuit you agree to accepting all liability if something were to go wrong.

Step 3: First Steps

Now that the safety stuff is out of the way and you have the parts, take one of the disposable cameras you got from the store and remove the cardboard casing (if it still has any). Now carefully pry the plastic casing open, try not to touch any electronics inside!

Once you have it open you should see something that looks a bit like an AA battery, this called a capacitor and it can hold a charge in the region of 330v. They can retain this charge for months so it needs discharging before you can touch it.

See the next step which explains how to discharge the capacitor using a screw driver.

Step 4: Discharging the Capacitors

You will need to take a screw driver with an insulated handle and touch the metal shaft of the screwdriver to the metal connectors coming out of the capacitor, in order to discharge it. You can wear rubber gloves if it makes you feel safer, although as long as you don't touch anything with your hands you should be fine.

It will create a spark if there is any charge stored in the capacitor. Once you have done this do it once more just to be sure as sometimes the capacitor can regain some charge due to the piezoelectric effect of the capacitor plates moving slightly when they change their state of charge.

Also remove the AA or AAA battery that is used for powering the circuit.

Repeat this step with the other disposable cameras you got.

Step 5: Other Cameras

Now with all but one disposable camera circuit you will need to de-solder the capacitors from their circuit boards. This might take some time, but if you are skilled with a soldering iron you can get it done in 5 minutes. I also recommend the use of a de-soldering pump here as this speeds up the process.

If you don't have a de-soldering pump then firstly heat one lead of the capacitor up and rock it one way. Then heat the other up and rock it the other way, it will eventually slide out.

Make sure to carry out step 4 on them first! Also be sure to leave one circuit board with the capacitor attached.

Once you have done this move onto the next step.

Step 6: Making the Bank

Get your piece of verroboard/stripboard and start soldering your capacitors onto it in parallel (so all capacitors are connected the same, positive lead to the positive side of the charger and the negative lead to the negative side of the charger). Look at the pictures if you are unsure.

You will also need to reinforce the thin traces of the verroboard/stripboard by soldering a piece of bare copper wire across both sides of the base (one copper wire across the negative and one across the positive side). Look at the pictures for more info. Without this the thin traces of the stripboard would blow/melt when you discharge the bank becuase of the high peak currents.

Solder some wires to one end of the board too, make them around 10cm long and thick (mains flex wire is fine). This is so you can conned the bank to the charger and discharge stick.

There are several images here to help you.

Wires need to be relatively thick in order to reduce the power lost in the wires.

You can use several lengths of thinner wire in parallel if you do not have any thick wire. I used some mains flex in parallel on mine.

What if I have lots of different value capacitors? can they still be used together?

The answer to this is yes. You can safely mix different value capacitors as their added capacitance will add up. For example, if you have two 80uF capacitors and three 120uF capacitors then they will all add up to make 520uF.

What about the maximum voltage rating?

Since we are putting them in parallel, the maximum voltage rating of the whole capacitor bank is the same as the capacitor with the lowest voltage rating. So if you had some capacitors in the bank that are rated for 330v and some rated for 350v, the maximum voltage you could use the bank would be 330v.

However you do not need to worry about this since we are using the charger that was included with the camera. This is only needed to be taken into consideration if you using a separate charger. The charger from the disposable camera will charge them to around 320v max (or at-least the one I tested did).

Step 7: The Charger

To charge your bank you can use one of the charger circuits that came with the disposable cameras (remember the one that you left a capacitor on?). Simply take two wires (use separate colours) and wrap the ends around the legs of the capacitors, then add some solder to the joints.

This will make for a basic charger, how ever, it will take quite a long time since it was only designed for use with one capacitor.

Put it back in its camera casing and run the wires so they come out of the case, you can snap a hole in the casing if needed. Use electrical tape to secure it all.

It is also a good idea to snap off the plastic around the battery area so you can easily remove the battery.

Step 8: Connecting the Charger to the Bank

Using the terminal block and wire, connect the charger to the rest of the bank as shown. Make sure you get the polarity correct in order to avoid an explosion.

Electrolytic capacitors don't like being connected in reverse polarity (plus they smell bad too when they blow!).

So be 100% certain that you got the polarity correct!

Step 9: Test Charge

Now for a test, insert the AA battery into the charger and press the charge button. Now becuase this charger was only designed to charge one capacitor, it will take quite a while to charge this many and it might take several minutes.

So for a test, give it 10 seconds of charge and then, using a plastic stick of some sort to move the discharge wire/electrode, touch it to the other wire on the bank. You should get some sort of a spark. Don't worry if the spark is small as you only gave it a short amount of charge time.

Now give it a 30 second charge and see how much the spark increases. Next do it for 3 minutes and you should get a huge spark loud spark!

You can connect your multimeter set to measure DC voltage across the bank and watch its charging progress. It will go from 0 to 300 odd volts, getting slower and slower the closer it approaches near full charge.


And that is it, you now have a capacitor bank made out of old junk, enjoy. Just NEVER let anyone touch it or shock anyone with it as it will cause injury. Its not a toy, it should be treated with the same respect as mains 230v/120v electricity.

In my next instructable I will show you how to make a fast charger for your new capacitor bank.

Step 10: Storing the Bank...

I have already mentioned this but I will say it again, always keep the bank shorted out like so when not in use!

If you are putting your bank into a project box then a simple relay arrangement and resistor can do this for your automatically.

Below is how I keep my large bank shorted out when not being used.

Step 11: An Enclosure to Keep It In.

You could also use a project box to make a switch-able enclosure for the bank.

Here is the one I made using a project box and a few switches from maplins. Notice the main discharge switch is under a red missile launch type of cover.

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    44 Discussions


    7 years ago on Introduction

    Haha about 8 months ago i finished mine mines 100 330v 180uf caps all wired up it rocks the house when it goes off

    2 replies

    2 years ago

    I'm gonna build this right now...

    Kman Meteor

    3 years ago

    do you know if you can get the used disposable cameras for free at Costco?


    4 years ago

    Hello! Im still reading this, 3 years later and still asking you, are you still planning on making an insctructable on how to make a faster charging circuit for this bank? I'm not that good at electronics so I dont know how to connect multiple circuits in parallel. I remember someone included a guide in his coil gun insctructable but he only used a couple of the components of a circuit board so it was compact and I thought it was cool except it didn't stop when it was ready, it had to be manually stopped. I just wonder if I could use one full charging circuit and then the necessary parts of the other circuits to get a fast, ratger compact, and not overcharging capacitator bank charger?


    That was the best disposable camera intructable. I'm thinking of connecting four circuits togather to charge faster, I tried it 4 minutes ago and putting two togather charged the cap. Bank in half the time!! So I was thinking, which is better?

    1- to connect the circuit battery and charging in parallel.

    2- to connect the circuit battery wires in series and giving them 6v while the charging cap. wires are in parallel?


    Thank you.

    1 reply

    You want to use the parallel because if you use the series and give the disposable camera too much voltage(e.g. 3 volts) it will kill the polyester film capacitor rendering your little circuit useless (unless you can swap out the components for higher voltage equivalents). what you want is more amps (but not too much) for the battery slot so have 3 to 6 C size batteries hooked up in parallel and you can have multiple charging circuits just make sure you are hooking them up in parallel and in the right polarity otherwise say good by to the one circuit whose polarity is reversed.

    Hope this helps and sorry for the bad grammar.


    6 years ago

    thanks dude, this was very helpful, I'm aiming to use it in a school project :-)


    6 years ago on Introduction

    So how do you make the fast charger then? Cus I have now gathered a selection of capacitors with a total capacitance of 25434 μF with the lowest 'max voltage' at 10 V.. Should be good if I can get it to charge relatively quick right?

    1 reply

    Reply 6 years ago on Introduction

    Basically its just a home wound multi-tapped transformer being driven by some form of push pull driver, secondary side rectified by some fast recovery diodes.

    Some form of feedback loop (comparator, opto isolator etc) is used to turn off the driver once the required voltage is reached.


    7 years ago on Introduction

    hey on some of your videos you have a toggle switch on your cap bank, im building a cap bank and charger in one. do you use a "special" toggle switch because of the high voltage? PLEASE reply

    2 replies

    Reply 7 years ago on Introduction

    This switch just connects and disconnects the low voltage power supply (12-36v) for the step up transformer driver. Its just a standard mains rated switch that you can get from old junk or electronics stores (I found mine in an old CRT TV and it came with an insulating sleeve).

    To connect and disconnect the high voltage side I use a PVC pipe with a bit of metal on the end ("chicken stick") which is connected to the negative side of the capacitor bank, this results in a bit of a bang when contact is made with a wire connected to the positive side ( :

    If you use a mains powered supply then its a good idea to earth ground the negative side of the capacitor bank.

    If you wanted to go solid state for the high current switching then an SCR is the best choice for high voltage and high current peaks. Its sort of like a high current transistor.

    Hope this helps.


    Reply 7 years ago on Introduction

    so how do you blow up diodes and resistors? (because i can see in the video you have alagator clips attached to them before they EXPLODE!!!) PLEASE reply


    7 years ago on Introduction

    Needin some help I got the whole thing up and running but when I went to charge up the second time nothing only getting power to the power terminals on the board. ??? Cheers

    2 replies

    Reply 7 years ago on Introduction

    O and after the first time that happend I switched boards and same problem only one charge then nothing. ?


    Reply 7 years ago on Introduction

    Not sure, could your tracks/wires be blowing becuase of the high peak currents? I would check everything with a multimeter to be sure. Make sure the charger is putting out voltage and that is being reflected on the banks rails.


    7 years ago on Introduction

    this instructable can be used to make a welder? i want it to weld some tabs to CR2032 batteries

    1 reply

    Reply 7 years ago on Introduction

    You could try it but I don't think it would work very well since you need steady heat for a few seconds for that sort of thing, this just gives a sudden big burst that lasts for a few milliseconds (creating pit marks in the battery's and making them look not so nice neat).