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!
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
- 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!
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.
- 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.