Sam's High-Energy Double Car Ignition Coil Driver... Update
>Date: Tue, 29 Dec 1998 16:50:09 -0700
>Subject: Re: High-Power Car Ignition Coils
>From: Tesla List <tesla-at-pupman-dot-com>
>Original Poster: Terry Fritz <twf-at-verinet-dot-com>
>At 09:49 AM 12/29/98 -0800, you wrote:
>I would use a space heater or electric oven element instead of those
Now THAT is a good suggestion :-)… They are in fact so bright that I
was getting a headache every time I looked at them… I tried to shield
the light with some cardboard but it almost caught fire:-(. Than I
tried using some metal heatsinks to shield the light and get rid of
the excess heat. The sinks are massive but still they get so hot that
the screws holding the metal to the top of the box melted off…
I also tried a soldering iron. Performance was very poor, with small,
low energy sparks and a very low repetition rate. I suppose the iron
has a much higher resistance than the lamps and so it lowers the
voltage considerably as it limits the current. Unfortunately I can’t
measure this because one of the coils was very mean to my multimeter
and killed it :-( … It does give me an idea though: If I use
something, which has even less resistance than the lamps, I will get
even more output. The only thing I know off that has a lower
resistance than the lamps and still limits the amperage are wire
resistances. I can get those in 100Watt ratings max. Do you (or
anybody else reading this post) know the resistance of a 500-Watt
Halogen lamp? How low could the resistance be before I start having
problems? I know too low a resistance is a problem because once I had
a spark to hit the top of the box. It is metal and has heatsinks
attached to it, with the resistance on the heatsinks. When the spark
send several tens of thousand volts trough the resistance it lowered
it, allowing such a huge surge of power trough that the SCR exploded
loudly with a beautiful shower of sparks and a cloud of smoke :-).
Nothing else was damaged though. I though the caps might blow but they
So, what rating should the resistances be for maximum performance? I
was considering ten 100Watt 100Ohm resistances in parallel (parallel
is the correct arrangement for power handling, right?), but maybe that
100Ohm value could go lower… Is there a way to calculate it? It would
definitely save me a lot of money experimenting, seeing that I have
already gone over $200 on this research… How can I keep the
resistances from overheating? If I use a 20Watt resistance, it gets
very hot. If I use five 100Watts resistances they get very hot too!
What can I do to prevent this and still obtain a good output?
You can use an inductor if the frequency is fixed and
>constant. Just adjust the reactance (Xl =3D 2 x pi x L x F) to the
>resistance value as your lights. However this may not work depending
>what the signal really looks like... Capcitors my not handle the
I was thinking more in the way of a shunted transformer or something…
But I think the resistances are a safer bet. I want to keep it simple
so everyone who wants to can make theirs without having to wind coils
or look for difficult parts… Besides, the power they waste as heat is
not a big issue as I am working at less than 1kW…
>>2- The insulation around the HV terminal is not enough to keep it from
>>arcing to the primary terminal screws, which are just outside it. I am
>>currently using insulation tape but it won=92t be long before it
>>down too. Has anyone done anything like this before? Any ideas on how
>>to insulate it better? Maybe some PVC pipes with epoxy?
>Drop them into oil! That's how I insulated the big 200 kV from the
>terminals in my GM coil. Epoxy likes to crack and get bubbles unless
>are really good at it. The oil should aid cooling too. I would get
>mineral oil or test regular auto type oils as an isulator. The model
>fuel sounds a little dangerous since sparks are like 10000 degrees C.
>may explode or do something bad.
As I explained in my last post (hope it came trough), I was intending
to use the oil in the fuel, not the fuel itself… I tried it and it
takes a lot more than just sparks to set it on fire… The oil is
designed to lubricate the engine, remember? You don’t want it to burn
otherwise it would stop serving its purpose as a lubricant.
I might indeed drop them in oil as you suggested because it is
probably the best thing I can do to insulate them… But one thing I
like about this driver is that it all fits inside a little 10 X 20 X
10cm (L X B X H) box with only the switch, potentiometer and high
voltage wires sticking out. You can take it anywhere because it is
light (a kilogram or so) and small. Having the coils under oil would
make it a lot more messy and difficult to move.
Anyway, the coils are encased in an aluminium can that is filled with
high-grade transformer oil (that stuff dissolves plastic cups!!!) both
for cooling and insulation… It’s the terminal that bothers me…
I think the car oils would be much
>cheaper. (I think this subject is from your other post today).=20
Ummm… I can’t get transformer oil and the motor oils I know off are
full of additives that make them look darker. At least the engine
synthetic oil I have is pure.
>>3- Has anyone tried ignition coil drivers before with good results? I
>>am REALLY interested in your experiments. Anything. Like, what was the
>>power level you ran your at and how did it behave. Has anyone got more
>>than 10cm long arcs from it? I think I hold the record for highest
>>power out of an ignition coil, but hey, I would be quite happy to be
>>4- How much power and voltage is a typical ignition coil really
>>designed to work at? I now know it is more than 50 watts. Maybe 200?
>>Does anyone know? What is the actual limit? Core saturation?
>>Overheating? Insulation breakdown? I wonder if it would saturate
>>before the power caused it to overheat=85 Unfortunately I don=92t
>>multimeter anymore:-( died while I was doing some tests on this
COMEON!!! I am absolutely SURE that SOMEONE on this list has done it
before… Can’t you be bothered to reply? So far only Terry and Gary
replied me… I need to know what other drivers perform like so I can
see what works and what doesn’t to improve mine!
I did build a driver I saw on Snock’s homepage. It consisted of a
light dimmer and a capacitor in series with the coil. When I turned
the knob on the dimmer it made a buzzing sound and the resistance
smoked… I could draw little sparks to a screwdriver by turning the
switch on and off though but the sparks were very dim.
>I found at 1700 volts input from a 1.7uF cap the GM coil wanted to die
>really fast. The ouput started to short internally at 200kV. Heat and
>saturation (I had no core) were not factors in my tests. In oil, the
>heating was zero. I ran at low average power levels though...
Hey, that’s good help!!! Thanks Terry! So I suppose I could expect my
coils to die before that… What kind of power were you running exactly?
A few watts, I suppose… What was (is) the output of your device like?
Does it arc or just make a few isolated sparks? Are they loud? Bright?
>> I haven=92t posted the circuit yet because it is under
>>have a word file with a full explanation of how it works and a parts
>>list/circuit diagram. It is the full instructions for building it. If
>>anyone is really desperate for some action I could mail it to you, but
>>I would rather finish my testing first=85
>I am sure many people would be interested in this for their coils
I sure hope so… I would really like to see all the work and money
that has gone into developing these prototypes be put into some use… I
want to use mine to power:
1- A good Jacob’s ladder <= Done! 1 meter long, 1cm apart at the
beginning, 6cm apart at the end.
2- Plasma globe <= OUCH!!! I turned it on and it looked real neat with
all the streamers dancing around… It was a bit weird because there
were so many of them that the entire bulb glowed, as if it was filled
with a blue fluid… When I touched it this large, bright pink streamer
zapped my finger. It hurt but wasn’t really what I would call an
electrocution… I think I have the wrong kind… It’s an OSRAM 100Watts
12cm diameter globe type incandescent lamp. My guess is that the
inside is air at a very bad vacuum… No way near what those real globes
3- A Tesla Coil… That’s my big goal… I now think I can run the coils
at 1000Watts for a few minutes run… 2 coils in parallel for some 40kV
output… If they can stand 200kV like your tests suggest than they
would make an excellent supply for a medium-small Tesla coil… I’m
still working on it though…
>> P.S. I know Terry has a GM high-power ignition coil to spark MUCH
>>further than this device will ever be able to.=20
>You bet it can! Don't even try to beat my record!! :-))
Well for now I have set a new record. I want everybody to know that I
have my double ignition coil driver running at 800WATTS!!! Yep, they
produce a 10cm long arc at 800Watts of energy and note well that this
800Watts is not the input energy. It’s the OUTPUT:-)
I want to see you beat that, Terry! But don’t worry… As I try to
squeeze more and more energy out of the coils your record for maximum
spark length is safe… For now…
How about trying that coil of yours at 800Watts? Think it’ll live
>> Sam Barros
>Great work your doing Sam!! =20
Thanks a lot Terry… You really shouldn’t thank me, you should thank
See, it was you with your GM ignition coil experiments that gave me
the idea to continue the work I had done with them long ago. When you
posted my 1inch record next to your 24 inches maximum spark length I
decided I had a lot of room for improvement. seen as Car ignition
coils are cheap and easy to get I decided to go ahead and try it… I
might not have beaten your spark length record but I sure beat every
single power record I know off! By far!
>BTW - My GM coil project is going slowly due to other stuff I am
>is still on my list however...
Yeah, now THAT is something I want to see… As soon as you tell us how
to do it I am going to get myself a GM coil and build one of those
drivers… It sounds really awesome…
To end my message I just though the people in the list might be
interested in knowing how my work is progressing…
I replaced the 300Watts Halogen by a 500Watts one. There was no real
difference in the output power but the coils produced a louder humming
sound. Since they were only getting warm I put the 300Watts halo back,
with the 500W one. Now I have 800Watts going trough the circuit… Those
coils must be pretty efficient because it is only at 800Watts that
they are starting to get warm… I will try 1000Watts tomorrow or the
day after. I don’t want go much beyond that because it would seriously
reduce the reliability and resistance of this driver… I am also
deigning a new trigger circuit. The one I am using now is from many
years ago when I still ran them at 20 watts and the SCR I have (TIC
106-M for 600V 5A) is getting too hot, even with the heatsink on… I’ll
replace it with a 16A trystor and I will increase the size of the cap
on the timer so it can trigger the bigger SCR… I’ll also make the
rectifier diode bigger. Change from an 1N4007 which is rated for 1000V
1A into a 1000V 3A one… I might even use caps rated for 650V if I can
get any… That would allow me to have a voltage Doubler at the input of
the circuit and run everything at 600V. If the coils don’t break down
they will arc at over 20cm distance setting new standards for
Anyway, as I have it now the 800Watts lamps are getting extremely
hot… They shine at full brightness when I run the coils at high
frequency and now that I have 800Watts they don’t shine full
brightness anymore at low frequency… But they do shine pretty bright.
Maybe 500Watts or more... The coils are also being clearly stressed.
The magnetic field induced on the core by the capacitor pulses is so
high that it causes the windings to repel it, mechanically vibrating
the coil… It actually shakes visibly which, although interesting to
watch (gives you a real measure of the power they are delivering), is
probably not a very good sign…
The arcs are now becoming somewhat spectacular… Yesterday I put a CD
cover between the wires… Both of them produce huge purple sparks that
raced across the surface of the cover, and when I got the wires a bit
closer to each other they punched trough… In less than a second the
whole thing was up in flames… The arc also eats aluminium foil and
solder quite fast…
I had the wires 11cm away and the lamps inside a box. It was late at
night and the room was completely dark. The distance was too great for
sparks to jump across and I could watch as the wires, rated for 40kV,
glowed trough the insulation… One of them emitted large moving corona
in all directions while the other’s output was visibly smaller… That
gives a clear picture to the saying that positive sparks are larger
than negative ones… The gap between the wires was filled with a blue
glow… Very beautiful… I watched it for hours…
Seeing this thing run a Jacob’s ladder is real neat… The arc itself
is just what you’d get from a large Neon transformer… But the fact
that you can vary the frequency on it makes for some interesting
results… I had a solder ladder… It was running fine until I decided to
place the electrodes together… Than it melted:-)… Now I have copper
ones and they run warm only.
I conducted another test. I increased the value of the 16uF 450V cap
across the resistance from 16 to 50uF. I expected this increase to
produce more powerful sparks but they got smaller and the lamps became
bright even at low frequency operation, indicating an increase in
power consumption. That makes it 2. Increase the value of the caps
that pulse on the transformer and the output goes down. Increase the
storage cap and it goes down too… Looks like I’m stuck to 20uF overall
capacitance until I double the voltage or something… Has anyone got an
idea of why this happens? At first I though that there wasn’t enough
energy to fully charge bigger caps when the coils ran continuously.
But reducing the frequency does not restore the old output spark
length and the sparks I got at 300Watts were the same length as the
ones I get now at 800Watts. And I still can’t increase the capacitance…
Well it’s 2:30AM and I’m feeling a bit drowsy… This message is
already far too big considering that only one or two of everyone who
reads it will actually bother to reply so I’ll end it now saying
HAPPY NEW YEAR!!!
Making sparks with “alternative power sources”…
"The Less You Know, The Better You Sleep"...
"Evolution Stops When Stupidity Is No Longer Fatal"
"If At First You Don't Suceed, Increase The Amperage"
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