Gallery, Projects and General > The Design Shop
Newfangled ignition coils
shipto:
As i said a igintion coil is basically a transformer you have a pulsed signal going in one side and a pulsed signal is then produced on the other side. mostly transformers take high voltage and reduce it to a useable level but in a ignition coil they work the other way around taking a low voltage (12v) and turning it into a high voltage (usually many thousands of volts)
Again I am guessing but i think the electronics in modern coils simply filters out interference and bounced signals so you get one single and strong spark for each operation.
They will not transform dc voltage which is why yours is getting hot you are just short circuiting the low end coil.
this may explain it better http://science.howstuffworks.com/transformer-info.htm
geoff_p:
With respect, shipto, I think you are barking up the wrong tree.
I'm not attempting to "transform dc voltage " and I most certainly am not "just short circuiting the low end coil". Shorting-out the coil would mean near-zero current through the coil (it all being by-passed by the short) so there would be zero heating.
My switch (lets call it "points") is in series with the coil-primary; the points are paralleled by a capacitor. What I haven't achieved is the 'ringing' that builds the primary volts to 200~300 volts as suggested by most descriptions of ignition systems.
As I said in my previous post, I've decided to use a new-fangled CDI system; I'm giving up guessing.
Geoff
Jasonb:
Saw this a bit late, have a read of this article, although its about making a buzz coil it does also describe how to use it for a single spark. I also tells how to test the coil and yes the bar in the middle is the negative to both primary & secondary coils.
http://gasengine.farmcollector.com/Gas-Engines/A-Sparker-For-Your-Engine-June-1988.aspx
Click the image gallery tab to look through the various diagrames.
J
russ57:
Jan Ridder (ridder.nu) has done some work on ignition systems for small engines, -co-incidently he has just updated the section. May be some clues there, even if not directly applicable.
geoff_p:
Indeed, Jason, Jan Ridder's work is fascinating - I spent most of an evening reading his page on ignition systems.
I had actually incorporated a piezo-ignition from a cigarette-lighter but found, quite independently of Jan, that the force required to 'squeeze' it is considerable. Of course, this is happening during the compression stroke so the poor old flywheel has to supply a lot of energy.
Anyway, as mentioned earlier, I'm going the CDI route: the system I ordered from HobbyKing has arrived and installation has begun.
Thanks for all your help and ideas,
Geoff
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version