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Sam's Ignition coil driver... 1100W now:-)

>Date: Sun, 03 Jan 1999 12:31:47 -0700
>To: tesla-at-pupman-dot-com
>Subject: Re: High-Power Car Ignition Coils
>From: Tesla List <tesla-at-pupman-dot-com>
>
>Original Poster: Scott Stephens <Scott2-at-mediaone-dot-net> 


 Hey, Scott, Thanks a Lot for the reply!!!


>You keep talking about watts. You need to specify energy (joules) per
pulse
>and the number of pulses per second or power (energy/time).


 As with Tesla Coils energy is not a good way to measure power of this
device. I think measuring the amperage and voltage going into the
primaries of the coils is more accurate. I have 300V,3.8A going in.
Unknown frequency but it makes an arc that sounds a lot like the
familiar 50Hz one we hear from transformers...



>Am familiar with this typical light-dimmer circuit. You could
probably hack
>a $5 lamp dimmer from the hardware store:


 I paid $12.5 for a Light dimmer kit for 750W, normal lights and a few
more dollars for a 1uF cap.. When I ran it the dimmer smoked. It was
in series with the cap and coil I think parallel arrangement will
cause it to explode, as it will present a direct short to the mains
and, at least the one I have, is not current limited. What dimmer did
you use? For halogen or for normal lights? Are you sure it has to go
in parallel to the mains?


>Oops, left off the line filter, to keep noise and flyback out of your
power
>line.


 My dimmer had a choke and some caps on it… Integrated noise
suppression they called it. Looked neat…


>>pulsing 300Watts trough 20uF of capacitance at 350V on them and
>>getting 10CENTEMETERS LONG ARCS!!!
>
>E=.5CV^2 so your getting 1.2 joules/pulse, and if you have a 50Hz line
>frequency with an SCR circuit, your only driving them with 50 Watts.
Your
>electrolytic caps dissipation factor is probably less than 10% (5
watts).
>Which means it should be a bit smaller than a beer can. 5 Watts in a
>photoflash cap should make fast sport of it.


 Hell no I don’t have electrolythics… They’d blow up with the voltage
reversals and I don’t run those 300W anymore. I have four PE caps
rated for 400V 1uF firing on the driver and a motor capacitor (what’s
the dielectric? It’s ac though) rated for 450V 16uF (took it from the
grascutter) in parallel with an 1100W resistance. I don’t think you
can take the caps into account only when measuring the energy because
when the SCR fires the circuit is open for 50HZ line voltage so it can
draw anything up to whatever the resistance limits it to. In practice
I found that the resistance runs maximum power (1.1kW now) when I
operate it in high frequency and somewhat less (but still much) at
lower frequencies. I know it is taking in the full 1.1kW because of
the heat the resistance develops (and how bright the 800W lamps lit up
when I still used them)


>>and the SCR, which is rated for 5Amps, needs a medium sized heatsink.

>I would use a snubber or free-wheel diode on that SCR. I've seen an
circuit
>for a kitchen stove's induction heater, which featured one. Basicaly
a fast
>turn on anti-parallel diode to the SCR.


 Why should I use it? Would it improve performance in any way? How do
I make one exactly? I use a 600V 12A SCR now, BTW…


>> Things are getting really interesting now. I KNOW these coils will
>>take at least 500WATTS before they start getting warm


 Uh, now that I have 1.1kW and they are getting warm but not hot I
think it would be safe to say they will take 1.5kW, maybe even 2…


>Because 4/5 of that 500 watts is heating other parts, IMHO. Your car
coil is
>probably only excited by the switching transient, and the rest of the
power
>is just going to your lamp.


 No, the lamp lights up full brightness, which automatically implies
that the FULL power required to make it light up full brightness is
going TROUGH the circuit… The actual power consumption is much higher
than 500W. Now that I run 1.1kW thw lights dim when the coils fire…
It’s dramatic.. Anyway, it MELTS SOLDER!!! Do you know how much energy
it takes to do that? I know a small NST can’t do it…


 Search the archives for recent discussions of
>car coils, and how to remove the steel core, which saturates & limits
power.


 Yeah, but than it runs pulsed only… At least Terry’s driver does…


>>I might even change C1 for a voltage Doubler
>>and pump some 700V on the primary to see if it can take the power.
>>Than I will get myself a bigger SCR and make a 4coil driver that would
>>handle 1000Watts.
>
>A circuit I simulated used a MOT to break down 2 to 4 series SCR's
(no gate
>trigger). Higher voltage means less dissapation. You might try using
a MOT
>as an inductive ballast instead of a resistor or halogen lamp. You
might
>also try putting a dimmer on the MOT to modulate its reactance?


 A dimmer? On a mot? The dimmers I know off don’t work. If you mean
running the driver off the output of the MOT than give up… at 1.3kV or
so even without a core the coils are doomed…


>>1- The halogen light gets EXTREMELY hot, and it is so bright it is
>>giving me headaches.
>
>Where do you think your power is going, the halogen lamp or the car
coil?


 BOTH! The lamp sure gets it’s share because it lights up fully… But,
being in parallel with the coils all the power it gets has to go
trough them first…


>>3- Has anyone tried ignition coil drivers before with good results?
>
>SEARCH THE ARCHIVE! We need a good search engine/method for the Tesla
>Archive. Then I, or some other SOB can use one of those cute standard
>flame-forms on everyone ;-)


 How do you search the archives? They’re so HUGE!

>>I am REALLY interested in your experiments.
>
>I am realy interested in yours, once you figure out how to most of your
>power into the ignition coil. I want to know what the maximum power a
coil
>can handle is. My crude thermal estimate told me to keep the
temperature
>under 150 degrees C inside the core, my power dissipation would have
to be
>under 200 watts. But that is more of a guestimate (SWAG).


 Thanks… Well, that’s it. The 1.1kW heater element is wired in series
with the driver. It will let trough a maximum of 1.1kW and that is
just what it does. So, power consumption is much more than power
output, but you could say it works like an unballasted pole pig… We
put heater elements in series with them to limit the power going in.
It’s not efficient but it works…
 I say 150 degrees core is really the limit. But now that I run 1.1kW
I think the power they’ll take is more than just 200W. Maybe 800?

>>this to run a Tesla coil, so, effectively it acts as a transformer and
>>not a resonator.
>
>You will get best performance if you used it as a resonant transformer.


 Well, that depends on what you call performance… Without a core they
will not saturate so they will be able to handle much higher voltages
(no core to arc to either) and pulse power. But that’s about it. They
will become pulsed power devices unable to arc or run useful stuff
like TCs and Ladders…



  Well, that’s it… Any questions or comments are welcome…


 Sam Barros.



==
 Sam Barros,
sambarros-at-yahoo-dot-com
ICQ#:15156975

 "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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