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Electronic ignition (sparking) system

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sarang1_in

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Hi all.
I want to built a simple sparker to ignite an LPG. Infact i tried it a long back with the help of tesla coil and a 555 timer IC based multivibrator. Now my requirement is with a microcontroller. When I use that old circuit with my controller AT89C51, I face a problem of EMI. My controller hangs.
Suggest something that will work on 6 to 12V and will give nice sparks.
I will take care of designing a PCB with firm isolation between 5V and 12V supply. But the radiated noise generated by sparking units is the worst I have ever seen. So please suggest something foolproof.
Thanks in dvance.
 
Thats a good suggestion. I mplementing pi filter is a good idea, but you need to know the exact frequency and or frequency range. So as to design the accurate filter. But with lot of headache it will reduce your conducted noise. Bypass capacitors are good option in case of low power noise or disturbance signals but in case of sparkers its not a good idea.
And what about radiated noise?
 
You have to isolate you uController not only from the sparks it creates and associated noise, but also from the surge of current your sparker draws..have you got a circuit?
 
I don't have a clear picture of what you are trying to do. If you are trying to light a burner and maintain the flame in the burner you might take a close look at appliances with electronic ignition systems. Many new gas (natural or propane) water heaters, furnaces, clothes dryers, etc use electronic ignition or a hot surface type of ignition system. They may produce some momentary noise but the noise is not continuous. Another approach might be to use a spark to ignite a pilot - so the spark need only be momentary.

Good luck with your project.
 
you could try the sparker out of an old piezo cigarette lighter.
can't think of anything simpler.

John :)
 
Hang on,
is this some kind of automatic device using a microcontroller ?

that makes more sense ... and you got interference previously ...

Well you could try hot-wire instead,
you won't have a problem with interference from that.
I made a press button thing ages ago for lighting the gas,
i used the filament extracted from an old car headlight,
but not at 12v, i think it was 3v but i may be wrong,
it was a long time ago.

John :)
 
Well let me put it like this. Hope it will make more sense in reading.

I want to make an LPG gas ignite with the help of an electronic circuit. I used the circuit which I designed specially for only ignition systems with a simple astable MV with the help of 555 and a tesla coil. (Noise and all were not the factors to be considered at that time)
Now I want to automate the burner as to make it on automatically and keep watch on it with an LDR. If there is no flame, the uC will activate a relay and thru that I will switch on the sparking unit. But though I used relay there is noise coming in the circuit.I used a cell of 3V for igintion circuit and I am simply controlling its on and off. Relays supply and uC supply are already isolated by an opto. As already said ignition circuit is powered by battery, so I think there is strong isolation anyway.
stevez said:
They may produce some momentary noise but the noise is not continuous.
What if because of noise your uC hangs and make all the port pins high making the relay ON continuously and thus making the sparker on. Something like thermal runaway in transistors.
akg said:
i think u have to check the powersupply wave form to the ic .. to make sure the supply is the culprit for hang.
It is not the culprit. It is as pure DC as it should be.
williB said:
You have to isolate you uController not only from the sparks it creates and associated noise, but also from the surge of current your sparker draws..
That is why I used a battery, but still the problem persists. :(
john1 said:
Well you could try hot-wire instead,
you won't have a problem with interference from that.
Chromel one? Well temperature is very high here aroung 450 deg C.
 
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