Shock Your Trick-or-Treaters

Introduction: Shock Your Trick-or-Treaters


I'm always looking for a new way to scare people on Halloween. This year, I thought up a way to make people think they are getting electrocuted when they ring the doorbell! It is very simple, requires little to no knowledge of electricity, is cheap, and can be built in only an hour or two once you have all the parts. It requires no permanent modifications to your doorbell.

Do not do this if you have a wireless or electronic doorbell. This will only work on the old-fashioned doorbells that are simply switches. You could fry electronic doorbells very easily doing this!

More Important:
I am not liable for any damages incurred through the use of these instructions. Even though it is very hard to hurt people with this, it may freak them out and get you into a legal mess. Use at your own risk!

Step 1: Theory

So, how does this thing work?

The purpose of a negative ion generator is to give extra electrons to air molecules, "ionizing" them. Negative ions are good for your health and make you feel better. In order to give molecules extra electrons, the generator must create a very high potential (voltage) between the generator and ground. In the case of this negative ion generator, it creates 15,000 volts.

Now, isn't that dangerous???
In short, no. High voltage doesn't kill people, high current does. A little math:

12v*0.1A = 1.2W
1.2W = 15,000v * 0.00008A

What this says is that if the generator was 100% efficient, it could achieve a maximum current of 0.08 milliamps. 5mA is the minimum current required for any lasting harm to be done, and this is well below that.

You only have to read below if you are very interested in high voltage and shocks.

Most static shocks occur due to capacitance with ground. Basically, every person is a walking capacitor. They are one plate, the ground is the other, and their shoes (or air) is the dielectric. You get charged up due to the triboelectric effect, and when you touch somebody else, you balance the charges in your capacitors. If you touch something metal connected to the ground, you discharge yourself.

This is one way to create a shock. The other way is to provide a direct path for the electricity to go, for example, touching two metal plates at different potentials at the same time. This is what causes most electrocutions. In this example, you are not a capacitor, but a conductor. These shocks are more effective because they are more controllable and more powerful, due to lower resistance.

I tried both methods when constructing this device. Method 1 (human capacitors) works fairly well when you are barefoot, but can barely be felt when you are wearing shoes. Method 2 (human conductor) works amazingly well no matter what.

Step 2: Materials

Here's some stuff you will need.

  • 12v input 15kv output negative ion generator: Get it from Goldmine Electronics for $13.95
  • 9-12v power source
  • Painters tape (the blue stuff)
  • Spray paint that matches the color of the door frame
  • Insulated wire, 18-24 guage, solid core

  • Jumper cables with alligator clips (makes wiring easier)
  • Wire cutters and strippers (scissors and your teeth also work)

Step 3: Let's Get Started!

The first step is to test your negative ion generator.

Hook up the red lead on the generator to positive, and the black lead to negative on your power source (9v-12v). You should be able to feel and smell a stream of cool, fresh air coming from the points. This is great if you want an air freshener, but we want to shock some people!

Cut off the points, and throw them away. They are pretty useless. Then strip the fat red wire they were connected to.

Connect up your generator again. Grab the exposed wire with one hand (you may feel a slight shock), and slowly move your other hand towards something metal. At about 1/2" (1 cm), you should get a pretty nasty shock. If you are feeling brave, try touching the red wire connected to the power source. It will give you an even more nasty shock from farther away.

Okay, great, everything seems to be working. Now move on to the doorbell.

Safety Notes:
  • These voltage are harmless to humans, but will easily fry electronics. Remember that after touching the red wire, you are charged until you touch something grounded or wait a few minutes. Never charge yourself up and touch your computer, TV, or any other sensitive electronics.

Step 4: Rig Up the Doorbell

Again, do not do this if you have a wireless or electronic doorbell, because you will fry it!

Cut 2 wires approximately 2-3 feet longer than the height of your doorbell. They will need to reach from the doorbell to inside your house. Strip the end of one wire 2" (4cm), and the other end 1/2" (1cm). Repeat for the second wire.

Bend the wire so that it matches the shape of the doorbell. Tape it below the doorbell with blue tape.

Run the wires along the door frame, taping where necessary, until they are inside the house. Make sure the wires never get within 1/2" (1cm) of each other.

This is pretty conspicuous. Don't worry, that will be fixed soon.

Step 5: Wire It Up Inside

Here's where all the action happens.

Connect the high voltage wire (big red one) of the negative ion generator to one of your doorbell wires.

Connect the positive low voltage wire (small red one) to the other doorbell wire.

Connect that same wire (small red) to the positive side of your power source.

To turn it on, connect the negative low voltage wire (black) to the negative side of your power source.

If you have done everything correctly up to this point, nothing should happen. You may hear a faint hissing or clicking noise from the negative ion generator, but no loud clicking (be sure to check both inside and outside.)

If you hear clicking at any point, the wires are too close together somewhere. Turn off the generator and make sure they're far enough apart. If they are very close, you may even get arcing (sustained spark). If it is arcing, you can easily see where your wires are too close and fix it.

Once everything's working, try ringing the doorbell. If all is well, you will get shocked.

Step 6: Make It Inconspicuous

Green wire and blue tape might discourage prospective victims a little too much. The solution: spray paint!

Remove your wires from the door frame. Place them on something you don't care about so that they can be painted. I used a scrap piece of plywood.

Pull out two 3' (1 m) sections of blue tape, and also lay them on your painting surface (sticky side down).

Spray paint the wire and the tape. Once the wire is dry, flip it and paint the other side.

Wait for everything to dry.

Step 7: Hang It Back Up

This time you will want to take more care in putting it up. It has to look completely natural, or people will not ring the doorbell. 6' (2 m) of tape should be enough to completely cover the wires with tape, all the way down, so that the wire is only exposed at the very bottom. If you do a good enough job at the top, people won't look down.

Step 8: Sit Back and Watch the Show

I suggest putting a "Warning: Bell Broken" sign above the doorbell. That way, sensible people and little kids will knock and not get shocked.

But, the teenagers who think, "They just put that there so they aren't annoyed by the doorbell all night. I think I'll ring it anyway" will get what they deserve.

Also, you better have good candy as compensation for getting shocked.

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    Lectric Wizard

    Your understanding of electricity is wrong & dangerous !! The resistance of your body is what determines the flow of current NOT the wattage of the power supply input. The human body is only 20-100 Kohms,depending on how wet your skin is,so ... 15KV / 20kohms = 750mA. More that enough to stop your heart !!! DON'T PLAY GAMES WITH OTHER PEOPLE'S LIVES !!


    Reply 10 years ago on Introduction

    Your statement would be correct if the output of the negative ion generator were an ideal voltage source. An ideal voltage source at 15KV would be able to source arbitrarily high currents. However, the negative ion generator is by no means an ideal voltage source. When you start trying to draw current from it, the voltage droops. This can be summarized in it's IV characteristic.

    You can think of it like this: when you short circuit a battery, the voltage across it's terminals goes to zero (even if it is, say, 9-volts nominally.) Some finite amount of current (say, 4.5 amps) will flow through your short. This is known as the "short circuit current." Likewise, if you remove the short and measure the voltage of the battery, it will be sourcing no current, but will have 9 volts across it. Now imagine somewhere in between. If you load the battery with, say, a 2-ohm resistor across the terminals, you might measure a voltage of 4.5 volts and a current of 2.25 amps. If you repeat this experiment with several different resistor values and plot current versus voltage on a graph, you will find that you can (approximately) connect all the points with a straight line. It will intercept the voltage-axis at 9 volts and the current axis at 4.5 amps. If the battery were an ideal voltage source, this line would be completely vertical (no matter what the current is, the voltage will be 9 volts.) It turns out that you can approximate (model) a battery as an ideal voltage source and a resistor (not the load resistor, a new resistor, and not a physical one: one intrinsic to the battery.) In the above example, that resistor's value would be 2 ohms. This is often referred to as the "internal resistance" of the battery. Better batteries have lower internal resistance.

    So how does this apply to the high voltage generator? The high voltage generator also has an internal resistance. If I were to short-circuit it, the voltage would also drop to zero, and the current would be finite, not infinite. This is how I determined that the machine was safe. I first determined that the machine would draw the most power when it was short-circuited. Then all I had to do was measure the short-circuit current. Since measuring the output side is hard, I used conservation of energy to simplify this measurement. I measured the power (energy per time) going into the input, and used the fact that the high voltage generator can not create power out of thin air. So, with the output shorted, the input drew 0.1 amps at 12 volts, or 1.2 watts. This means that the output will not be able to pump more than 1.2 watts into my body. At 15 kilovolts, this would only be 80 microamps.

    There is a subtle misdirection here: if I am drawing 80 microamps from the output, there is no way it will still be at 15 kilovolts: the voltage will droop, just like the battery did. However, this can only lead to less current draw, not more, so my estimate is conservative. In fact it's not really an estimate so much as an upper bound to what the actual value is.

    So I bet after all this you are still concerned with V=IR where V is 15 kilovolts and R is your body, so I must be larger than I claim. The fallacy here is that V is 15 kilovolts. The high voltage generator has an open-circuit voltage of 15 kilovolts, but as soon as you load it when, say, yourself, that voltage droops. And so using my measurements and conservation of energy, we can find what it droops to. Assuming we are putting 80 microamps into the body, with the body having a resistance of 20 kiloohms, we see that the actual voltage across your body is only 1.6 volts! The reason it feels different from touching a AA battery is due to capacitive and other transient / AC effects created by the high voltage.

    So it turns out, compared to the resistance of your body, the internal resistance of the high voltage generator is huge (hundreds of megaohms.) It's a really crappy battery. So you can think of it like touching a 15 kilovolt source through a huge resistor. Another way to think about it is that the high-voltage generator is a better current source than voltage source.

    If you'd like high voltage with lower internal resistance, consider grabbing onto some high-voltage power lines. Then you can experience 750 milliamps of current through your body (but not for very long!)


    13 years ago on Step 2

    Where can I get a negative ion generator


    Reply 13 years ago on Step 2

    they are no longer avalable from that site. I have searched all the places I know. Do you know where else to get them?


    Reply 10 years ago on Introduction


    Reply 11 years ago on Introduction

    An old air cleaner would have one (120 volt version).

    Adam Manick
    Adam Manick

    Reply 11 years ago on Step 2

    You canals use a transformer with a pushbutton


    Reply 13 years ago on Step 2

    I do not know of any other place. If you keep watching that site, they will probably be back in stock within a few weeks or months. You can try the 120VAC version, but you must be much more careful.


    13 years ago on Introduction

    19 comments in a row 20 if you include this one :-)


    Reply 13 years ago on Introduction

    chocolate covered resistors