Hi to all :)
I have seen in many sites, drivers for antiparallel ignition coils. This topology supposed to produce opposite magnetic fields which doubles the output power. But there is something that i don't quite understand. Ignition coils have an internal diode at the HV output, so they produce only positive peaks. How those peaks can be opposite?
In the schematic there are two ignition coils in an antiparallel connection. Waveforms 1 and 2 are with each output without the diode. Waveform 3 is the real output between the HV outputs of the coils.
Do i miss something?
Thanks
Jeg
Quote from: Jeg on May 27, 2013, 03:15:40 PM
Hi to all :)
I have seen in many sites, drivers for antiparallel ignition coils. This topology supposed to produce opposite magnetic fields which doubles the output power. But there is something that i don't quite understand. Ignition coils have an internal diode at the HV output, so they produce only positive peaks. How those peaks can be opposite?
In the schematic there are two ignition coils in an antiparallel connection. Waveforms 1 and 2 are with each output without the diode. Waveform 3 is the real output between the HV outputs of the coils.
Do i miss something?
Thanks
Jeg
Seems interesting. But the output diodes confuse me. They only allow one direction on the outputs and they are the same direction. I dont see how they conduct with each other, unless it is counting on reverse breakdown of one of the diodes, or both alternately if there is oscillation between pulses to the primary of the coils.
Havnt seen this circuit before. Thanks for showing
Mags
Thanks for the reply Mags. Perhaps are some ignition coils that the diode can be extracted so to reverse it. Anyway, i just wanted to be sure that i didn't forget my electronics lessons at school. :)
ps. I really can not understand their mania to put internal diodes at ignition coils and tv flybacks! :D
It is indeed very common to find diodes built
into flyback transformers; but ignition coils?
Unless this is something very new I've not
encountered it yet. Spark plugs are really
not polarity sensitive.
Maybe I was misunderstood. There are 2 diodes shown on the schematic on the outputs. I agree, there should not be any in the coils. Its just that the diodes are biased for 1 way and both are in the same direction, but the circuit has the coils operating out of phase, so only 1 coil at a time can deliver to ground? It looks as though the 2 outputs are meant to be the output. Its a simple enough circuit to try with or without diodes or even reversing one or the other. But what are ya gunna do with all that lightning? ;)
Mags
Quote from: Magluvin on May 29, 2013, 01:39:29 AM
snip...
But what are ya gunna do with all that lightning? ;)
Mags
And the x-rays, gamma rays and anti matter particles that lightning can produce! :o (Do a search for terrestrial gamma ray and anti matter burst).
reference to anti matter from lightning : http://www.wgwa.org/storage/newsletter_files/vol25no1/thunderstorms.pdf (http://www.wgwa.org/storage/newsletter_files/vol25no1/thunderstorms.pdf)
Cheers
The high voltage impulses can be
utilized to power an experimental
Ozone Generator or even an
experimental Nitric Oxide/Nitrogen
Dioxide Generator.
It's nice to be able to come up with
ways to produce certain very useful
chemical products on a small scale.
Yes, there are risks and hazards which
the experimenter must be fully aware
of so as to learn how to avoid dangers
to life and limb.
Quote from: SeaMonkey on May 29, 2013, 01:32:09 AM
It is indeed very common to find diodes built
into flyback transformers; but ignition coils?
I should have done a quick search before posting this. You are right. There are not any diodes at the output.
Well, what if i charge a micro oven cap with this rectified 30KV and have a spark gap of about 2KV (about 2mm)? Will i blow out the 2,2KV cap? How can i calculate the charging time between discharges?
Tnks Jeg
Well.... wow.
First, "antiparallel" would imply something other than what is happening. What is shown is two transformers of opposite phase. Each ignition coil has its output rectified by the single diode, producing the chopped DC waveform with maximum "ripple" characteristic of a half-wave rectifier. The two outputs are out of phase and so can be combined into something that "looks" like the output of a fullwave bridge: a DC pulsation with maximal ripple at twice the supply frequency, with the "holes" in one coil's output filled in by the other output. But this wastes half the power from each coil, doesn't it? My reaction to this is... "so what?" If all you are looking for is high voltage like 30 kV and more, a TV flyback is an easier and perhaps more efficient way to get it. Cheaper too. But ignition coils are neat and fun too, it's just that a good one costs 30 bucks or more and you are stuck with its own primary and its internal connections between pri and sec.
Second.... yes, you will blow your oil-filled paper-and-foil MWO capacitor if you subject it to 30kV! A "2kV" spark gap isn't going to protect you for very long, and even that ~1 uF cap charged to even ~2 kV is lethal and will require special handling. The usual scattered clipleads on a workbench will not be suitable for this experimentation. For high voltages like 30kV and capacitor charging, you really _really_ need to be careful and know what you are doing, because the first mistake you make _will_ kill you, almost guaranteed.
Third, to calculate how long it will take to charge the cap will require knowing how much current your charging system can supply.
If you want to see the effect of charging a 400 picoFarad cap to 30 kV or so, you can look at my flyback driver jacob's ladder videos. If you want to charge a 1 uF cap to 30 kV, even one rated for that voltage .... please be sure to have someone record it on video.
TV Flyback driver Jacob's Ladder showing the effect of added capacitance:
http://www.youtube.com/watch?v=4XRwlNCF1PU (http://www.youtube.com/watch?v=4XRwlNCF1PU)
The best Jacob's Ladder I was able to make, using a heavyduty automotive ignition coil and a driver using 555 and 2n3055:
http://www.youtube.com/watch?v=VNL8QTS0sM0 (http://www.youtube.com/watch?v=VNL8QTS0sM0)
I have an auto ignition coil that I took apart and it has no diode inside.
When the points open the backemf charges the capacitor up and then
recycles the primary voltage back into the coil causing a second spark
and continues to repeat that until the losses will no longer charge the
coil and make a spark. The capacitor extends the spark making a longer
duration spark making a better fuel burn in the engine.
What kind of coil did you find the diode in?
Norman
http://en.wikipedia.org/wiki/Ignition_coil (http://en.wikipedia.org/wiki/Ignition_coil) >> Construction:
"A single-spark system has one coil per spark plug. To prevent premature sparking at the start of the primary pulse, a diode or secondary spark gap is installed in the coil to block the reverse pulse that would otherwise form."
Quote from: norman6538 on June 01, 2013, 05:18:39 PM
What kind of coil did you find the diode in?
Norman
Norman i didn't find it anywhere. I just confused it with flyback transformers, and that was in contrast to the anti parallel connection designs for making double voltage. Through output diodes you just double the pulse frequency as Tinsel said.
Jeg