Playing with Electricity

© June, 1994 by -=* Gandalf *=-

DISCLAIMER: I didn't force you to use this information. I have made every effort to make it correct. Any problems you might have as a result of using this information are yours. You don't have to play with electricity to have fun. Some of the information contained here is from personal experience and your experiences may not be the same.

I did look most of this stuff up in books. It doesn't make it any better, but it is at least accepted by some of the people who count and perhaps supported by research somewhere.

Free to distribute as long as the disclaimer and copyright notice are retained.

-+* Gandalf *=- an46901@anon.penet.fi

Playing With Electricity

From time to time there is a question asked about electricity and sex. It often shows up in many forms. Everything from 9 volt batteries to TENS units and Violet Wands. You can get a 9 volt battery for less than a dollar. While TENS units can cost over 200 dollars and sometimes require a doctor's perscription. There are other ways to get an electric shock. Some are safe, some are not. I'm also hoping to clear up some errors that have been previously posted.

The Basics

First off electricity can be dangerous. And most people will tell you that it isn't the voltage that can kill you it is the current. Well, I'll present a more accurate picture if I can. The problem is that votage and current are directly related and you need to include resistance. Ohm's law states that (V) voltage divided by (I) current is equal to (R) resistance (V/I=R). You can also arrange the formula to get I*R=V and V/R=I. Since we are using electricity on the human body, we have a small problem. The resistance of the human body varies from day to day, person to person and due to a whole lot of other factors we don't have room to list. In general, between your hands, the resistance is 2,000 to 50,000 ohms depending on conditions. Lethal current can be as low as 20mA (.02A). Any current over 15mA (.015A) is considered dangerous. Other interesting currents to know are 1mA for feeling, 5mA for pain, 10mA for some paralysis, 30mA breathing can stop and 75mA for ventricular fibrillation (the heart doesn't beat right) and possible death. a current of 4A will stop the heart. At 5A you can burn skin. Note that as long as you stay away from vital organs, high current may not be fatal. Vital areas are the spine, the brain, the heart, and probably the lungs/diaphram area. I've seen a few sources that suggest that 100ma (.1A) is needed to kill someone, but for safety, I'd stick to lower current.

Note: Most of the currents and what happens came from different sources. How the electricity was applied to the human body was not described. It will also vary from person to person.

A CHART!

This is just a chart of the above information.

Why Household Current Is Dangerous

If you connect directly to a normal household outlet, one side of it is grounded the other side is "hot". For those outside the U.S., your individual country may be different. Most if not all plumbing (unless you have plastic) is a good electrical ground. So connecting directly to an outlet is foolish. Also in most cases water is an electrical conductor. So virtually any plumbing is a conductor and so is a basement or garage floor. In general a cement floor will also conduct electricity. Cement is usually poured on top of the dirt. Since cement is porous and may contain water, you could be standing on a good ground.

The hotdog cooker is an interesting application of just what enough current can do to meat (or meat like stuff). If you put 2 nails through a board so they are about the length of a hotdog apart, tie each wire of a power cord to each nail. Place a hotdog on the ends of the nails and watch how fast it cooks. Remember that the human body isn't all that much different than a hotdog.

To sum up, if you wish to use household current you need isolation between the the power source and ground, and you better reduce the voltage so that the current isn't too high.

How It Feels

DC Current
Battery voltage sources should be limited to about 30 volts (15ma*2000=30). Note that 30V is about the maximum DC voltage you should play with. You can connect several batteries together to get more, but it isn't worth the trouble.

DC, what you would get from a battery and some types of power supplies, usually just gives a burning sensation and then kind of goes away. This is rather dull and unexciting. DC is also the most safest to play with because the battery is completely isolated from any ground. If you use a power supply that produces DC, it is probably isolated from ground, but don't count on it. Anyway, DC sources are pretty dull.

Pulsating DC Current
Battery charges deliver a pulsating DC. You can get a cheap 12 volt 1A battery charger for less than $10. The one I have is almost 15 volts. Even at worst case, it will deliver 7.4mA (14.87/2000=.0074) to the human body. You will notice that the ratings for the charger don't match my numbers. First of all, a lead acid battery can deliver as much as 2.2 volts per cell which gives us about 13.2 volts for a normal "12 volt" car battery. And you need more voltage than the battery to charge it. I measured the voltage with a meter. The actual voltage under load will be a little less, but for use here, it is relatively insignificant. A 12V 4A charger is not much more dangerous than the 1A variety. I didn't have one handy for testing, but you can expect to get a little more current from it, but probably still less than 10mA on a human body. So much for the technical part.

What pulsating DC feels like is a sort of buzzy feeling like AC current. Pulsating DC sources are usually battery chargers. Most if not all battery chargers use step down transformers and provide isolation from ground and are therefore safe. Pulsating DC has been used to great effect in a few movies, but the torture sceens were greatly exaggerated. While the battery chargers used create nice sparks for the camera, we have just proved that it isn't all that bad.

AC Current
AC is mostly like pulsating DC as fare as feel. Limit AC to about 24 volts. You can get a transformer at places like Radio Shack. Make sure the primary is isolated from the secondary. We don't want to accidently get zapped with 120 volts. Many appliances are isolated from the house current by a transformer. Some AC adapters will provide low voltage AC. Ignore the current rating of the transformer since the load will always be a relatively high resistance.

AC always reminds me of the old telephone generators. Many science, electricity and electronics teachers have had an entire class hold hands while the teacher cranked the generator. For those who have had this experience, Pulsating DC and AC feels a lot like that. But here is the tricky part. AC can vary in frequency. Differences in frequency change how it feels.

Low frequency AC is the buzzy kind. Very dangerous. Treat it like DC. Don't use too much voltage here. This will cause more pain than anything. Probably the most unpleasant.

I'm not sure where the transition is, but high frequency AC changes all the rules. If the current is low enough, you can get well into a million volts and still be safe. A Vandegraph generator is basicly static electricity. There is also the Telsa coil. What makes these voltage sources different is that they can't sustain high current levels, but allow wonderfull fireworks displays. The other reason these types of sources are ok is that you can't touch both sides of the power. They belong more in the realm of static electricity. While static charges sometimes hurt, they are usually safe. Another effect of the higher frequencies is that you can burn the skin if held in one spot. Electrical burns of this type are just as bad as a burn from fire or chemicals. From what I understand, a Violet Wand is of the high frequency, high voltage low current variety though I haven't seen one. I do have a pretty good idea how to build something like it though.

[Note from SD: many people have confirmed that a violet wand is a form of Tesla coil, and that while the violet wand is general considered very safe - it's the one kind of electrical play above the waist that's not considered very high risk - there is a danger of burns to the skin from sustained contact. There is also, under certain circumstances, a possibility of setting garments on fire with a violet wand (unfortunately, exactly what those circumstances are - for example, what kinds of fabrics having received what kinds of treatments - is not known, but there are credible reports of such occurences]

The End

If I scared the hell out of a few people with this then great. Electricity is fun and dangerous at the same time. If you didn't know what you were doing, hopefully you have a clearer picture. If you still don't know what you are doing, maybe you better think a litte more about play with electricity.

Bibliography

Shrader, Robert L., Electronic Communication 5th ed., McGraw Hill, 1985

Grob, Bernard, Basic Electronics 5th ed., McGraw Hill, 1984

These are basic texts and should still be in print. Don't buy them to get this info. All the info from both books contained here would fit on one page.