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Old 04-30-2010, 11:07 PM
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ozmatic ozmatic is offline
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Join Date: Jan 2009
Posts: 15
Hi Harvey,
I just logged in to post my schematic, and found you had already done it! - Which is great, as I am having severe trouble uploading mine - I cant get it small enough for the limits..Anyway, you got the 555 circuit spot on - amazing.
R1 = 7.5k.
R2 = 12k.
cap bank = 0.3uF.
pin 5 goes to ground via 0.01uf cap.
R3 =1200R.
There is an LED +7.5k resistor between pin3 and 6Vground.
Q1 = 2N2222A,and this is where It starts to differ from what you have.The collector of the transistor is connected to 6Vcc. and the emitter goes to the relay coil through a 180R resistor.The other end of the relay coil goes to 6V ground.The 2 battery negatives are not connected [except by scope probe grounds].
The HV circuit goes like this : 12V battery positive is connected to one of the relay contacts through a 10 watt pot set at 40R.The other relay contact goes to the primary of the ignition coil.
12Vbattery negative is connected to the common terminal of the ignitiion coil. It also goes to the common pole of a DPST switch. One of the switching poles of this switch is connected straight to the spark gap, and the other is connected to it via a MUR140 diode [anode first].This enables the diode to be switched in and out at will.
The other end of the spark gap is firmly connected to the ignition coil secondary. And that`s it - if you can follow it.
When I built it -I wanted total isolation between the two circuits, but I forgot about those pesky scope grounds! I am still thinking of putting a separate ground for each channel in the scope.
Your circuit looks interesting,but it is impossible to separate the common connections on these ignition coils- they are sealed. I might try it with a suitable transformer.
Many thanks for your input - its very much appreciated, and it might seem off topic, but its not - and this circuit wont hurt anyone.
Chris
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