Coil Voltage Question

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Model T Ford Forum: Forum 2010: Coil Voltage Question
Top of pagePrevious messageNext messageBottom of page Link to this message  By jeremy gibson on Tuesday, June 01, 2010 - 04:37 pm:

So when I have one hand on the head and a spark plug lead in the other and someone turns on the ignition by accident(maybe).

How many volts are going through me?

Or put it this way, if 10 volts = 1 kick up the arse how many should I give them :-)

(feels like drinking 12 cups of strong coffee)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Tuesday, June 01, 2010 - 04:54 pm:

I would be better to use an electronic instrument to measure the resulting voltage.


Top of pagePrevious messageNext messageBottom of page Link to this message  By jeremy gibson on Tuesday, June 01, 2010 - 05:48 pm:

I think you might have a point!

At least I now know why they are called trembler coils now, I am still trembling.


Top of pagePrevious messageNext messageBottom of page Link to this message  By richard wolf on Tuesday, June 01, 2010 - 05:56 pm:

I was changing a coil once going down the road and touched the wrong place on the coil. WOW and I decided it was not a very good idea so I pulled over and stopped to change it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Berch on Tuesday, June 01, 2010 - 06:00 pm:

That's funny Richard. Maybe they should add that to this new law. No texting while driving or changing coils. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Bohlen on Tuesday, June 01, 2010 - 06:40 pm:

Remember it's the Amps that kill you not the volts.
If I remember my High School Physics class.

Ron am I right? :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, June 01, 2010 - 06:47 pm:

Actually most people who are listed as having been "electrocuted" aren't in fact killed by the power of the electricity. Usually it is the volts that shock them and they die from cardiac arrest. I am often contacted by people who think it might be fun to hook up a T coil to something to give somebody a jolt when they don't expect it. I won't participate in their prank and try to warn them that they could do serious damage to someone who just might have a bad ticker and maybe not know it. Electric shock should be avoided as being dangerous to all.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andrew K. Deckman on Tuesday, June 01, 2010 - 07:06 pm:

I have a neiber that hooked a coil up to his car and when he was not in it, it would shock you. He did not have a external shut off so he would have to take the shock to open his own car, he know it was coming though. He does not do it any more.

Yes, it is the amps that kill but your own resistance changes with mineral content and water content. So you could be fine for one time then have trouble the next with the same situation.

Static electricity is 10's of thousands of volts low amps. As well as a taser but some people die with that so always be careful!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tman on Tuesday, June 01, 2010 - 07:17 pm:

The average 12 volt coil puts out about 30,000 volts a 6 volt coil will put out about half that. An electronic coil puts out over 50,000 volts. But at less than a 1/4 amp.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck - Shreveport, LA on Tuesday, June 01, 2010 - 09:24 pm:

The spark gap on the spark plug is what controls the voltage here. This isn't open circuit (no load) by any means.

The voltage is probably about 5 kV with a 0.025-0.030" spark plug gap.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, June 01, 2010 - 11:04 pm:

Pretty darn close Seth. In fact I would say "close enough". The rule of thumb that is commonly used is 75,000 volts per inch of gap but that is at one atmosphere of pressure and between 2 round balls with smooth surface. With 4 to one compression you have effectively 4 times the gap so the volts go up. High Voltage is funny stuff that is hard to control and hard to measure accurately. The measuring equipment tends to have too great of an effect on the objects being measured.

TMan:

I don't think a typical 12V coil puts out twice the voltage of a typical 6V coil although that might seem logical. Some might do that but the primary of a typical 6V units just has fewer turns of heavier wire as compared to its equal 12V counterpart. This is why typical 6v battery ignition draws about twice the current (amps) of the typical 12V system. The energy in the coil is simply how strong the field is which is determined by AMPs x turns of wire. Thus twice the amps at half the turns (6V) is the same energy in the coil primary as half the amps and twice the turns (12V).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert E. (Bob) Blakbourn, Gautier, MS. on Wednesday, September 08, 2010 - 10:54 pm:

Years ago when jeans had metal buttons instead of zippers, I was leaning over the fender of a car and removing wires from spark plugs one at a time to find out which plug was not firing. All went well until I pulled a plug wire with a bad insulator boot. The high voltage proceeded up my arm, through my body and back to the vehicle ground. For a clue as to how it got back to ground refer to the second sentence in John Regan's last post. (:|


Top of pagePrevious messageNext messageBottom of page Link to this message  By Garnet on Wednesday, September 08, 2010 - 11:58 pm:

So why is it that some folks can grab the spark plug terminal on a running engine and say "yup, that one is firing or no this one isn't..."

I've seen it in person and couldn't believe what I was seeing. The few times my hands ever grazed a plug I ended up flat on my backside!

Is it rubber soles, or rubber brains?

Regards,
Garnet


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey on Thursday, September 09, 2010 - 12:04 am:

Ya, had that happen to me once Robert E.
Not very erectafying.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kent Greenhalgh on Thursday, September 09, 2010 - 12:42 am:

I would not attempt to count the numerous times I have been shocked by high voltage ignition circuits.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis - Lyons, GA on Thursday, September 09, 2010 - 12:20 pm:

Garnet,

I think some people just have a better tolerance for it. My grandaddy would pull a plug wire, stick his pocket knife up in the boot, tell you to crank it over, and say, "Yep, that one's firin'." I'm not about to do that and when it does happen occasionally, "Yep, that one's firin'" are not the words I usually utter.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick - (2) '26's - Bartow, FL on Thursday, September 09, 2010 - 12:33 pm:

An old family friend, John Cornwell, who is now deceased from old age, told me back in 1970, when I first got my Model T that, as a boy up in Ohio, in the 1930's, he and his friends would drive the old family Model T out to the swimmin' hole and go fishin' using the magneto and a long wire, to shock 'em to the surface. I have heared of this but have never seen it done and don't know if it is really true or just a tall tale. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Howard Tobias near Pgh, PA on Thursday, September 09, 2010 - 02:37 pm:

Jim-
I think that is how they get worms to come out of the ground.
The way I tested my ignition was to use a neon light tester (the kind with 2 leads to stick in a AC wall plug) held against the wire. There seems to be enough electrical field around the wire to light the little orange bulb.
Howardelctrified


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis - Lyons, GA on Thursday, September 09, 2010 - 03:54 pm:

They actually have that fishing thing down to a science. 54 volts, I think it is, that is supposed to be the optimum. They make a thing that will fit into a tackle box that generates the proper voltage. I've not seen one, but I know giuy who has bought one. Says it works great. Just don't get caught. I always thought it killed the fish, but he says it just stuns them and they float to the surface where you can get 'em with a net. The effect is only temporary, according to him.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James Bartsch on Thursday, September 09, 2010 - 05:17 pm:

I found a wood carrying case with a hinged lid at a flea market that had a tag "Lodge Initiation Torture Device" Inside the box were two good model T coils with long wires soldered to the secondary and alligator clamps on the end. Similar wires and clips were on the ground terminals. There was a place for a 6 v dry cell and some resistors to adjust the primary voltage. I kept the coils and trashed the box.

On the electric fishing worm 'digger' we used the hot side of 120VAC house current and 2 ft iron rod to encurage worms to surface in the lawn. It worked well, but you had to be careful not to kneel on the wet grass in a way that made you part of the circuit. That was before the moon walk but I bet it still works.

Respectfully, jb


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary H. White, Sheridan, MI on Thursday, September 09, 2010 - 07:59 pm:

Back in my Navy days I was working on a radio/transmitter set when I got a real smack that made me jump about a foot off the floor. I swung around to clobber the guy who had hit me in the ass with a 2X4 and found nobody there. I had touched the 300v RF (Radio Frequency) lead to the output tube with my hand as my arm was resting on the test rack frame. I've been bit by spark plug wires several times but nothing like that RF jolt.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, September 09, 2010 - 08:16 pm:

The amount of shock depends on how good a conductor you are and how sensitive the part touching the conductor. Dry hands and dry body parts will react differently than wet hands and wet body parts and the callous on the hands makes them less sensitive.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By CoreyWalker, Brownsboro, Texas on Thursday, September 09, 2010 - 08:28 pm:

I was doing some troubleshooting once, shorting plugs with a screwdriver bent over somehow that my bottom lip was near or touching the radiator support rod. My wife was cranking slowly in front. Don't know what went wrong but the shock went from my lip to that rod. My lip swelled up like I'd been hit in the jaw. I weld so I get shocked all the time but nothing like that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Stroud on Friday, September 10, 2010 - 03:15 am:

In the mid '70's , I worked in a local welding/machine shop that was owned by a gentleman that went to work for Ford as a pattern maker in '29, and moved back here in '41 and opened a shop. He had an old lathe that had a minor short in it. He never felt it, but anyone else that touched it would jump. He also could not wear a battery powered watch, they would go dead in a very short time. He could also "divine" for water. He could take two bronze rods and hold them as tight as he could and they would cross each other when he walked over the water line that lead into the shop. I tried it and I could feel a very slight pull, but that was all. From that experience, I knew that there is a very big difference in what people feel with electricity. Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Friday, September 10, 2010 - 03:54 am:

Many dozens of stories I could tell on this thread.
Gary et al, NOTHING hurts as much as an RF burn. RF runs on the surface (of your skin) and hits every nerve ending it can.
If you ever get to know me, you may notice that I usually have one hand in a pocket when just hanging around. That is a habit from years around high voltage and RF. I have been zapped many times and it generally does not bother me much, but that doesn't mean I like it. I have never been seriously jolted. And I have never had an RF burn. But I have known many people that have.
Electricity is funny stuff. What you think should injure you can hurt, but do no harm. And what you think shouldn't be dangerous, can kill you. I have worked around high voltage, low voltage and RF most of my life. I have a pretty good idea what is dangerous and what isn't.
If you don't understand electricity, be careful with it. It is overly simplistic. But the common rule is that voltage is what you feel. Amperage (current) is what kills you. Spark plug wires are high voltage/low current. But, then again, is the health condition question. Don't take chances unless you know it is safe for you. And then, don't take chances.
Work and drive safely, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By curtis morin on Friday, September 10, 2010 - 04:03 am:

i was told it was better to run a 12 volt coil on a six volt system,it would last longer is that correct?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Howard Tobias near Pgh, PA on Friday, September 10, 2010 - 09:43 am:

Electricity is lazy,it will take the path of least resistance.
Howard


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Friday, September 10, 2010 - 03:41 pm:

Curtis,
It depends upon the coil. Many "12 volt" coils are actually 6 volt coils. Many cars have an external resister that drops the 12 volts down to about six or seven volts. When the starter is engaged the resister is bypassed giving the full balance of the battery to the coil for a hotter spark and easier starting, especially in cold weather. You have to have and understand the actual specifications for the specific coil to determine the true voltage demanded for that coil. Coils really work across a wide range of voltages. But as voltage and demands change, so does the current and efficiency. Coils and other wiring components can be damaged or even start a fire if things go too far off spec.
Then, again, some coils are actually 12 volt. Start switching is done differently. And you have to have and read and understand the spec sheet.
Drive carefully, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Garnet on Friday, September 10, 2010 - 04:43 pm:

That divining business David is a learned art. I've never witched for water, but I have located underground cables numerous occasions using only a pair of copper L-wands. Even found a dropped set of keys in tall grass this way! I don't know why it works and I imagine that Physics says it can't work - but it works!!

Garnet


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis - Lyons, GA on Friday, September 10, 2010 - 07:14 pm:

When I was a kid, my parents built a house out in the county. The next door neighbor had recently built his house as well. He claimed to have divined the location of his well and had a pretty good one. He offered to do the same for us. My mother, being the devout Baptist that she is said "Ain't NOBODY doing no water witchin' on my property." They hired a fellow to bore a 24" shallow well. First try, he hit solid rock at about 12-15 feet and had to move to another location. Second try, he hit solid rock and managed to wring off the shaft on his boring rig, so he gave up. Daddy resorted to having a 6" deep well drilled. The guy drilling the well had a tank full of water to cool his bit, but emptied it before he got the well done. Being the same guy who drilled the neighbor's well, he went next door and asked to use his well to fill his tank. He ran the neighbor's well dry. My parents were a bit embarrassed, but at the same time thought it was kinda funny that he had been bragging about divining that well and how much water he had and on and on. The well man got our well done and went next door to see if he could go a little deeper and get the neighbor some more water. When he hit that next pocket, it blew his bit out of the ground and the resulting deluge of water washed a ditch along the side of the neighbor's house that exposed his foundation!

I can't say that I know how divining for water works, or if it even works, but the neighbor had the last laugh on that deal.

Boy, talk about thread shift....Sorry.


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