Introduction: Caps N' Sparks

I have recently found out how much fun it can be to short circuit the leads of a charged capacitor after zapping myself while opening a disposable camera.

It wasn't long before I decided to start messing around with capacitors and creating some sparks. Soon I noticed how time spending it was to connect the capacitor to the power supply, charge it, disconnect it and just then, short the leads.

So this came to me, a little device that will charge the capacitors and disconnect them for you. The best part is that the speed at which they are connected and disconnected from the power supply can be regulated.

Even though in this Instructable I will be using low voltages such as 20v, I believe you can, by using higher voltage capacitors do the same with much bigger sparks and fun.

So let's get started!


I am NOT responsible for any Zapping caused to you by this project. If you choose to add higher value capacitors and use a higher voltage I am not responsible for whatever the outcome of such ideas is. It might end up being fun or it might end with some nasty burns.

The Schematic is to be opened using Eagle Cad.

Step 1: Gathering It All

First of all you will need to get hold of all of this parts, I do not know what they cost in your country but here in Peru I paid about
S/. 34 which is about US $11.40

Materials you will need:

-1- DPDT Switch (Double Pole Double Throw)
-2- LED Holders
-2- LEDs (Your choice of color)
-1- 20k Potentiometer
-1- Knob for the Pot
-2- DC Barrel Connectors (Female, The ones you can screw on the enclosure)
-2- SPDT Relays 12v Coil
-1- DPDT Relay 12v Coil
-2- 1N4004 Diodes
-1- Perforated Board Small
-1- NE555 Timer IC
-3- 1/2 Watt Resistors
-1- uF Capacitor
-1- 0.1 uF Capacitor
-1- L7812cv
-1- 3.3 uF Capacitor
-1- 22 uF Capacitor
-3- 1000 uF Capacitors 25v (You can choose a higher value if you want, I found 3000 uF was enough)
-2- Banana Female Jack
-1- Enclosure for the Project + Screws

-1- Strip of Female header Connectors

You will also need:

-Soldering Iron
-Power Supply Capable of delivering 20v
-A second power supply from 12v - 20v
-A couple of pliers
-Helping Hands
-Electrical Tape

-Red Wire
-Black Wire

Step 2: Principles of It

The project works the following way:

1.Electricity comes in from the 16v input and passes through a 12v regulator.

2.It then goes to a 555 timer which creates a signal that travels to 3 relays turning them on and off.

3.The 2 SPDT relays do the following:
    -One Is switching on and off the connection between the 1000 uF capacitors and the 20v Supply
    -The other is switching on and off the connection between the Output to Discharge the capacitors from them
So When the relay allows current to flow to the capacitors, the Output is disconnected. When the connection to the 20v is blocked to the capacitors, the Output is switched on so you can short circuit the leads.

4.The other DPDT relay switches the LEDs on and off. One LED will the lit and the other will be off.

5. If the User decides to vary the speed at which the relays switch on and off, he can do so by moving the potentiometer to the left or to the right. This will affect ALL of the relays.

6.Once the capacitor is discharged, it charges back again to repeat the process over and over again.

Step 3: Step One

Now you have to take a decision here.
Depending on which perforated board size you have you might be able to fit everything on the board.
If you are like me, you will need to place the two SPDT relays glued on the inside of the enclosure.

Quick Note here:
You CAN replace the two SPDT relays for one DPDT and connect it the same way those were connected, in that case you might just get everything on the board.

So, First of all, choose where to put those 3 capacitors. I Would recommend you to put the components in the same places I did as that way you can ensure you will have just enough space for everything.

Step 4: The Relay Part One

Now its time for the DPDT relay to find its place on the board.

It will have the role of controlling both LEDs. It will have to switch one ON and the other one OFF.

Along with it place the 1k resistors near to the rear outputs of the relay as they are the ones who will keep the LEDs from burning at 12v.

Step 5: The Regulator Part 1

Next add the L7812CV Voltage Regulator, preferably near one the edges of the board so that you can add the heatsink without having space issues with other components.

It will have to take the First Input as I like to call it, in my case it is a 16v transformer, and take that voltage down to 12v so that once it is connected to the 555 timer, you will have the relays switching on and off to charge the capacitors and disconnect them from the Secondary Input, which is the 20 Volts.

Step 6: The 555 Timer

Okay, it is time for everyone's favorite IC to get his own place on the board.

Place it near the DPDT relay so that you won't need a long wire to connect it to the Output pin of the Timer (Pin 3). Even though You might want to place it facing one of the longer sides of the board so that you can easily route a cable from Pin 3 to the SPDT relays.

This little guy will have to create the signal that will switch the relays on and off. It is imperative you place that 3.3 uF Capacitor between pins 1 and 8, else you will find out that the output will not be 12v, it will be lower and not enough to switch the relays on and off. Something that took me quite a while to figure out.

Do not miss the 22 uF Capacitor between pins 1 and 2, the negative side goes on pin 1 same for the 3.3 uF Cap.

Step 7: The Regulator Part 2

Next to finish the 12v regulating circuit, add the 1 uF and the 0.1 uF capacitors next to the 12v Regulator.

Between pins 1 and 2 goes the 0.1 uF one and the other between pins 2 and 3.

Make sure you connect the negative side to the middle unless you want to get POPS! Instead off Sparks.

Step 8: Down to Soldering

The time has come for you to turn that soldering iron on and get down soldering.

You can take a look at the schematic and wire the components as shown. Nevertheless I will list the connections to be made as we move on.

In this step;

-Solder the two capacitors as I mentioned before to the 12v regulator.
-Solder those 3 1000uF Caps in PARALLEL.
-Connect the 3.3 uF Capacitor to pins 1 and 8 of the 555 and the 22 uF to pins 1 and 2. Negatives go on pin 1.
-Make a connection between the input pins on the relay, not the ones of the coil, the ones below.
-Connect one 1k resistor to the normally open output and the other to the normally closed.

Step 9: Preview - What You Should Have by Now

By Now you should have:

The Regulator Connected
The 555 Connected - Missing Power Connections
Relay Wired Missing Negative on Coil and Input pins need Connection
3 1000uF Capacitors in Series
2 1k Resistors connected to the relay

This is What you have to add now:

-A connection between Pin 4 and Pin 8
-A Connection Between Pin 6 and Pin 2
-Connect Pin 3 to one of the Coil pins on the relay.
-Connect a 1k Resistor Bewteen Pin 7 and Pin 8 (Not shown on the underside of the Perforated Board)

And here is a Preview, What my Circuit Looked at that Point

Step 10: Drillin' Some Holes

Time to pick up your Dremel Tool/Rotary Tool and drill holes to this board.


In the short time I have been in electronics I have found out that wires connected to boards normally break off at the connection after they have been pulled or moved.

The solution to this problem is drilling a couple of holes in the board through which those cables will pass and so the connection will not receive any stress from movement of the cable.

You will need a drill bit a little thicker than the one that of the holes on the perforated board. Drill the holes one infront of the other. Make sure you drill them near the components that will have a wire attached to them.

Step 11: The Potentiometer

Now it is time for us to be able to regulate the Wave Length of the signal generated by the 555.

Take your 20k Potentiometer and a short piece of wire, you can use what is left of a components lead after you have clipped the excess off.

-Place the wire between pins 1 and 2

-Clip the Excess


-Solder wires to Pins 1 and 3

-Place some Heatshrink to cover the pins and help to stop the cable from breakin off so easily with movement.

Step 12: The Relay Part 2

Time to Solder those two SPDT relays together.

First lets put them one next to the other and wrap them with some electrical tape.

-Now that they are together, place a wire connecting the 2 pins closest to each other. They belong to the Coils of the relays.

-Now wire the other two Coil pins together.

-Place a diode on the normallyclosed pin of one of the two relays, I chose the left one. The Diode should have the line facing away from the pin.

-Connect the normally open pin of the other relay to the Input pin of that one you chose that has the diode.

-Also add a wire comming out from that normally open pin (later you will see why).

-Add another diode to the Input Pin of the other relay, the line facing towards the relay.

-Finally add a cable going from the two outmost pins of the coil, it will be a ground connection and a cable to the middle coil pins which will go connected to the Pin 3 of the 555 timer

Step 13: First Connections to Board

Now that you have both the potentiometer and the relays with their connections ready you can go ahead and connect them to the board.

This is how it goes:
Pass the wires through the first hole from the underside of the board.Pass them back through the other hole and pull so that you dont have a giant loop at the top.
Those two cables will go connected to Pins 6 and 7 of the 555 timer

Now do the same for the relays, there are 3 wires to be connected to the board, two from the coils and one for the input pin. Remmember I told you to add that extra wire?

Step 14: Connections Under the Board

Now follow some of the missing connections between components.
If you placed them the same way I did I recommend you to use flexible wire not single core wire as they easily break.

-The capacitors are missing a connection to ground, add a cable there.

-Take a cable from the middle pin of the Voltage regulator (Ground) and take it to the coil of the DPDT relay and from there to Pin 1 on the 555 timer.

-Take another wire and make a connection from the output of the regulator to pin 8 of the 555 timer.

Step 15: Drillin' Some More Holes

Time for the enclosure to take shape.

Take a couple of thicker drill bits and start drillin' the holes for:

-The Potentiometer (1)
-The LED Holders (2)
-The Barrel Jacks (2)
-The Switch (1)
-The Output Banana Jacks (2)

Step 16: Connecting the Barrel Jacks

Take those two barrel jacks and 5 lengths of wire.

The 3 negative wires, let them be long. The other 2 make them short as they will go to the switch which is very close to the jacks.

On the First Jack take Two wires and connect them to the negative tab. Don't Forget to add some heatshrink to cover the connections.

Now add a short wire to the positive tab.

Do the same with the other Connector.

Now take both positive ends and connect them to the switch, the middle pins of the switch.

Add 2 more wires to the switch, one will be going to the relay to charge the capacitors and the other to the board, to the regulator.

Step 17:

This step is actually optional, if you do not want to use LED holders you may skip it.
Take the LEDs and add just a tiny bit of solder to the tip of the leads to ensure they will not accidentaly disconnect from the connectors we are going to make in a moment.

Take a strip of femaly header connectors, count two pins and remove the third one and repeat with the sixth one.

Now using a cutting tool, can be a saw or a cutting disk on a dremel, cut through the header strip in the space you have just created.

You should now have two, two pin female header connectors.

Add some wire to the pins and take them to the board, where the two 1k resistors are.

Insert the LEDs on the connectors after putting them inside the LED holder.

Step 18: The Banana Connectors

Depending on which type of connector you have, you might need to dissasemble it to put it on the enclosure.

Anyways, solder a wire comming from the diode on the SPDT relay to the banana jack. This is going to be the positive connection.

Now do exactly the same but this time use the second wire on the barrel connector, the one that has two wires comming from the negative tab. This is going to be the negative connection for the output.

Re-assemble your banana connectors and place them in your enclosure.

Step 19: The Final Touches

If everything has gone right you will probably have quite a mess of wires

Take a couple of safety seals to group the wires depending on which side of the board to they end up on.

After doing so, the box should look nicer.

To finalize take a hot glue gun and glue the relays and the board to the enclosure.

Step 20: The Decisive Moment

It has come down to this, the moment when tension rises...

Connect the 16v Power supply to the right barrel connector.

Connect the 20v Power supply to the left baller connector.

Flip the switch.

You should, as soon as you flip the switch, hear the relays go on and off.

Carefully connect a couple of wire to the banana connectors.

-Slowly and Dramatically make the two wires touch each other and Hopefully, the spark will come out-

Step 21: Time for Fun!

If you have reached this step it means you have created your very own Sparkin' Fun Maker

Go and Show it Off!

Have fun!

Most important of all, turn the lights off, and check out the spark in the dark, They look amazing.

And To Finish Off here's Kiara To Make your day even Happier :)

GranTotem Out.


Himers made it!(author)2014-08-07

This is great!!! I might use this to make an automatic coil gun.

dean14111 made it!(author)2012-05-20

you know what. i found out about caps the exact same way you did, and man does it hurt!!! im going to post an instructable about how to build somthing sourt of like yours, but i dont have all the parts yet, so check up on me because ill be doing that instructable soon!!

GranTotem made it!(author)2012-05-20

Well I am Happy to learn that you want to make one like mine.

Since you are going to do so, you might want to try using a disposable camera to charge the capacitors. That means that they will have a charge of about 400v if im not wrong.

That is some pretty nice sparks I bet. Just take into account that it might not work like mine, you might not be able to make it spark like crazy. Already at 20v the metals, when they touch each otherm they stick together. They melt. So at 400v you might end up with a soldering iron.

If not you might want to use capacitors with a larger capacitance, say 1 Farad.

Happy Building!

R.A.T.M made it!(author)2012-05-20

I have a bank of 100 330v 180uf caps they can put a quarter size hole in a coke can the dont stick very much (some times) but because it just vaporizes the wire

fostersfriend made it!(author)2012-05-24

Dam bro thts nearly a kj so ...... Did u collect those or did u just buy em

R.A.T.M made it!(author)2012-05-28

Collected them but had the hole thing including the charger done in a week

fostersfriend made it!(author)2012-05-28

Nice it cool hearing from Peru.... My mom grew up there

R.A.T.M made it!(author)2012-05-29

What i live in the U.S in montana?

rocketman221 made it!(author)2012-05-20

I have a capacitor bank that is 5200 farad at 2.5v and it will make some nice sparks and even melt 14awg solid copper wire. It takes a long time to charge up though.

R.A.T.M made it!(author)2012-05-28

see mune charges in 30 seconds

GranTotem made it!(author)2012-05-20

Ohhh, So what changes the "melting" capacity of the bank as you call it is the capacitance and not the voltage?

Because when I was designing it, I played around with values and voltages, and it seemed like they both affect. The higher the voltage and the higher the capacitance the bigger the sparks. When I lowered voltage the sparks decreased in size.


rocketman221 made it!(author)2012-05-20

The stored energy measured in joules changes the "melting" capacity.
When you double the voltage the stored energy quadruples.
Here is a calculator that shows the stored energy in a capacitor.

Your bank charged to 25v has just under 1 joule. Mine charged to 2.5v has 16,250 joules. A common disposable camera capacitor 120uF at 330v has 6.5 joules.

My bank is made with boost caps which won't discharge quickly. They will discharge in about 5 seconds at the fastest.

GranTotem made it!(author)2012-05-20

Sir, You have just boosted my mad scientis level.

Please tell me more on how you made this capacitor bank.
Also, what is the main use of a capacitor bank, I've heard about them but I can't see the use except for doing what my proyect does and maybe melting metals together.

Where on earth did you get a 5200 Farad capacitor?

On the shop I go to, they barely have capacitors up to 100F and they are huge.

rocketman221 made it!(author)2012-05-20

It's actually 2 2600F caps in parallel (Maxwell BCAP0010). They are normally used to supply or store large bursts of power. I bought them to make a led lantern flash light that will run for an hour and charge in 30 seconds, but I haven't got around to building it yet.
I got them as surplus quite cheaply. They are very expensive new. I got mine from electronic goldmine a while back. Sometimes they get more in but they sell out very quickly. An ebay search for "maxwell ultracapacitor" turns up a few of them.

dean14111 made it!(author)2012-05-21

actually ive already made one and the charger to go along with it, so even before i saw your instructable i was planing on making one that was more powerful and had a charger built-in. i just need more caps and yes i do get them from old disposable cameras from cvs or walgreens (you can get them for free if you ask right) so anyway keep a look out for that instructable. :)

mechatr0nix made it!(author)2012-05-24

I have got an idea for you. Could you consider making the power supply small and portable(will not last long,) and then make a pocket arc welder.

GranTotem made it!(author)2012-05-25

I tried soldering to pieces of metal together but the charge that this generates isn't enough to melt the metals.

It will although make the two pens stick together a bit but they easily come apart.
I would have to use a higher voltage and probably, as some people have told me that would kill the relays due to arcing unless I used a snubber or something like that. I still have to go over this circuit again to make it more efficient in terms of the relays and the supposed arcs that are created between contacts.

So if you can tell me how to get AC from a 9v battery I would be happy to try this out.

mechatr0nix made it!(author)2012-05-25

That is all way beyond me. The most advanced thing I have done is turn off my TV with my Arduino but maybe one day when I go to university I will return to this.

jimvandamme made it!(author)2012-05-25

You can calculate the energy stored in each capacitor using the formula 1/2 C (V squared), where C is the capacitance and V is the voltage. Usually C is in the microfarad regoin, so pretty small, but when you increase the voltage the energy goes up by the square. 10 times the voltage, 100 times the energy! (The result is in Joules.)

I design, build and run big radar transmitters, and some use capacitors of around a microfarad. Not much, but they charge up to 40, 000 volts. When you short across THAT, you'd better have ear protection on, and stand behind something solid, and don't look at the arc.

GranTotem made it!(author)2012-05-25

That sounds awesome.
Purely Awesome.

ladyscrubber made it!(author)2012-05-24

This brings back old (old) memories. Back in the 60's while stationed in Fort Sill, OK and living in a barracks with 20 to 30 other electronic nerds we played with Capactors as well. We were using 120v Caps and larger, charge them up and after lights were out, would launch them into the air. When they came down the leads would migrate closer together and the blue arcs that came out were brilliant. Of course some of us were not that brilliant and some of US tried to catch them in flight. Not recommended for the sane.

Thanks for the memories.

Treknology made it!(author)2012-05-24

Ah, yes. The days of the Capacitor-Box all charged up with a sign saying "Do Not Touch This Box" and waiting for some fool to pick it up. It taught people to regard safety signs.

milnuete made it!(author)2012-05-24

Very fun instructable, some people use capacitor banks to feed high energy pulsating lasers. Regarding your 16 ohms equivalent age I just want to tell you that:
1 ohm = 1.139 x 10^(-12) sec/cm

so you would need to multiply 16 ohms by some particular constant distance (in cm) in order to get your right age, which is that? or is it a secret?

Best Regards

GranTotem made it!(author)2012-05-24

Ahh My dear Friend,

I recommend you to read again carefully.


gardenville made it!(author)2012-05-24


Interesting project. Could you minaturize this small enough to go into a model trolley car. The point of the spark would be where the trolley pole touches the overhead wire.

I want to control the trolley with Radio Control and use a Battery for power. This way I don't have to have the overhead wire "HOT". The "Cap's N Sparks" device could create the spark at the where the trolley pole touches the overhead wire. The spark would make it look very real.

This youtube video shows the kind of spark I am looking for:



GranTotem made it!(author)2012-05-24

Yes I believe you can, You would have to replace those 2 relays for 1 DPDT, something I forgot to explain how to do.

Remove the extra relay for the LED's. Now instead of 3 1000 uF caps just buy one of a higher capacitance say 5k uF.

You might have some problems with the relay. I have received some commentaries at HackADay saying something I didn't know about, called arcing.
So you might want to wait a little bit while I try to figure out how to "protect" the relays from these arcs. Also you might have to use a 9v battery to power the relays unless you can find a 3v relay.

Regarding the charging of the capacitors, well, you might have some problems here as well. How will you charge them, I was recommended to use only 1 power supply, but in this case, if you have your trolly on a rail you could have the 20v running through the rails onto the capacitors and have the overhead wire be connected to the 20v ground to do the short circuit.

If you could send me a picture of what the trolley looks like I would be happy to help you.

Sincerely GranTotem

Iridium7 made it!(author)2012-05-19

You should also put a warning saying that you should never place either lead going to your heart, face, or spine. That will also help. Good 'ible though. I'll be sure to make one sometime.

LaserDave made it!(author)2012-05-24

Hahaha - that's a good one. Surely, you are being sarcastic, right?

I look at it this way, if someone needs warnings so basic, or even about the incredibly obvious possibility of electric shock - they should NOT be playing around with electricity/electronics in the first place.

Maybe gardening would be safer - hmm, but then you'd have to warn about potentially sharp trowels, not to eat fertilizer, possible drowning from the water hose, sunstroke, insect bites etc. etc. People need to take some responsibility for their own actions, instead of making it everyone else's to keep them safe. Just a thought. (Or does this have to do with rampant sue-happy people in the US who will blame the author if they get hurt?)

Great comment though!!

GranTotem made it!(author)2012-05-19

Yeah... I once read about a guy who took a charged car audio capacitor, one of those big ones, and touched both leads with his tongue... He thought it was discharged.

static made it!(author)2012-05-22

Folks this is great nice build for the living room, unless someone near is listening to AM radio. To see the ultimate capacitor discharge machine see the geek group's thumper.

DrSimons made it!(author)2012-05-19

Nice project. I agree, this is a great thing to do and there should definitely be some videos up in here. For anyone new to playing with capacitors, it's probably wise to point out a few things (sorry if you already mentioned any).

1, never use a voltage higher than the capacitor's rating. At very least it will leak, and worst it might damage the cap and/or explode.

2, when using electrolytic caps (the big black ones) NEVER wire it backwards. If the polarity is wrong it WILL explode. So pay attention to the lead that has a bunch of minus signs (-) going up the side.

3. Be wary of thin wires vaporizing or the contacts welding together. When I first did this using a disposable camera (which comes with a built-in charging system, by the way!) I actually welded a screwdriver to the capacitor terminals.

GranTotem made it!(author)2012-05-19

Thanks, Do you think I should add a precaution slide to the instructable?

4. Never Ever touch both leads of the capacitors with any part of your body when charged.

DrSimons made it!(author)2012-05-20

Couldn't hurt. Might consider mentioning safety goggles too, a sufficiently powerful discharge could send sparks into your eyes.

BrefelanDesigns made it!(author)2012-05-19

Congrats! You have made a 555 Flyback transformer Driver!
You might want to also check out ZVS Flyback drivers...
You might also be interested in (Youtube user) Telsabang's HV Power supply:

biolethal made it!(author)2012-05-19

Cool, i like the finished look of this bank. I'm working on programming a 2.6Kj 400v capacitor bank right now. The capacitor bank you built may benefit from a bypassable SCR to switch the capacitors through things, so you get more efficiency and less switching losses.

GranTotem made it!(author)2012-05-19

Thanks, Ill take that into account. By the way your project not only sounds fascinating but worthy of a video! I would love to see the sparks that 400v would create.

Kiteman made it!(author)2012-05-19

Video! Give us video!

GranTotem made it!(author)2012-05-19

Video it Shall be! I'll make one as soon as possible.