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Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Hi guys, Here is my latest update of an ignition coil powered straight from the mains (220V AC). BUP314 transistor is switched directly by TL494 at 6 KHz. The output voltage of the coil is around 60KV so it must be dipped inside an oil bath.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
I would use fullwave rectified mains (probably with a capacitor in series for current limiting), you can then draw out the arcs much longer than the starting distance because of continuous-wave operation.
And be careful, the coil will overheat if you run it too much current.
Registered Member #1132
Joined: Mon Nov 19 2007, 06:15PM
Location: Slovenia
Posts: 84
Yep try rectefied mains, gives a nice high current 300V.I used a 1:1 isolation transformer to limit the current at switch on since i had two 2200uF 400V filter caps.But i guess it would be better to use much smaller ones (like the filter caps in PC powersuplys)
And yeah as he sead ignition coils can heat up quite some when driven at these powers. With my driver i pushed a coil so hard it arced over internaly to the metal can and then to one of the poles.I was driving it at resonance with a H bridge directly off rectefied mains.
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
Can you hear the 6khz when you operate this thing? It doesnt seem to be in the video (only 50hz), and i was wondering if that was simply the low quality audio?
Maybe its worth removing the ignition coil from its metal can, so you can have a larger tank of oil for the whole thing, it also removes the possibility of the can rupturing from internal pressure.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Steve Ward wrote ...
Can you hear the 6khz when you operate this thing? It doesnt seem to be in the video (only 50hz), and i was wondering if that was simply the low quality audio?
Maybe its worth removing the ignition coil from its metal can, so you can have a larger tank of oil for the whole thing, it also removes the possibility of the can rupturing from internal pressure.
It is the sound quality; otherwise it squeezes like crazy...
I've never have a problem with overheating the coil by operating it with this driver despite it sucks 3.5A from the wall (220V). That's the advantage of pumping high voltage pulses into the primary...
Registered Member #1132
Joined: Mon Nov 19 2007, 06:15PM
Location: Slovenia
Posts: 84
Well no wonder 50Hz is so dominant because he is basicaly choping up the 50Hz mains signal at 6Khz. If you send in DC at the points you put in mains you should get much more power. Just grab the first moderetly sized rectifier bridge you find and stick on some caps in the 500uF range.If you have trubles of pluging this thing in and your breaker trips then just use something as a balast. I found a mains traformers secundary can be used as a balast with the primary shorted.
Also the 70uF filter cap dosent realy need t o be that big. I used only 2uF and works great.At these high freqencys caps dont realy need to be big anymore.
Oh and i dont have any plans on riping up the ignition coil. But i do have plans of trying to make a homemade single layer HV transformer.And try induction heating too
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Berni wrote ...
Well no wonder 50Hz is so dominant because he is basicaly choping up the 50Hz mains signal at 6Khz. If you send in DC at the points you put in mains you should get much more power. Just grab the first moderetly sized rectifier bridge you find and stick on some caps in the 500uF range.If you have trubles of pluging this thing in and your breaker trips then just use something as a balast. I found a mains traformers secundary can be used as a balast with the primary shorted.
Also the 70uF filter cap dosent realy need t o be that big. I used only 2uF and works great.At these high freqencys caps dont realy need to be big anymore.
Oh and i dont have any plans on riping up the ignition coil. But i do have plans of trying to make a homemade single layer HV transformer.And try induction heating too
Hi Berni, I'm affraid you do not understand the circuit. I cannot use the DC - it wouldn't work. Actaully it would make only single spark and that's all. The design with 2uF cap you are talking about is most likely half bridge, but this is single switch and it is the changing phase (AC) which allows to discharche the big cap. The cap must be so big because the discharging is only at 50Hz while the charging is at 6Khz (through the primary of the coil). I can rise or lower the power by adding more capacitance of the big cap and I know for sure that at 2uF the power is very low...
The usage of a single switch design directly for rectified (and cap smoothed!) mains would be a certain killer for the transistor. Maybe it could be solved with some kind of curret limitter but that's completely different circuit design and I would rather go for half bridge anyway...
Registered Member #1132
Joined: Mon Nov 19 2007, 06:15PM
Location: Slovenia
Posts: 84
Yeah i used a full H bridge to drive it. I used a garden hose,glass and laqour to keep it from arcing over. But that wont help if the coil arcs over internaly and bye bye coil.
So i guess its the best to use just a half H bridge.
That transistor of yours is quite beefy so it should handle big powers in a bridge.
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Ignition coil on mains
