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Per I am looking at the hall sensor turning on when the magnetic is in front of it. Other then that it’s an open circuit.
This output can be amplified by the addition of a capacitor to create a resonance circuit.
QuotePer I am looking at the hall sensor turning on when the magnetic is in front of it. Other then that it’s an open circuit.I agree - but this also means that it 'short circuits' the output of the 555 ocsilator to ground when the magnet is in the 'Firing position' - just the opposite of what is required.
I wonder if the clue is that the Hall effect Device only triggers the 555.When I look at the one shot circuit shown on the 555 data sheet, it seems that the input is normally high, and the trigger pulse is a brief low. When the Hall effect device sees the magnet? Then the output goes from low to high for a fixed time period, which seems to be what is required to operate the sparking circuit. It is shown in the little graphs under the circuit drawing on the 555 data sheet. Does that help?But I am still not sure how the back half of the circuit works.MJM460
I specifically referred to Don's first shown schematic and on that the 555 is running as an astable multivibrator (oscillator)- having a 1mS. firing time and an adjustable delay before next auto firing ~ this kind off a trembler, running all the time.The circuit the the right of the 555 is an current amplifier where the right most transistor is a high voltage device (and they usually requires quite a bit of current as input).My first suggestion cuts the signal to the current amplifier when a spark isn't required and my second suggestion shorts the firing signal for the duration of not wanting fire.None of them gives a perfect firing timing as they haven't got any influence on where the oscillator is in it's sequence, but if the firing is as rapidly as the coil can sustain it will not matter on a slow running engine - but would be a problem over a certain RPM ....I hope that I have explained it in an understandable way (I'm an Electronic Technician by education and profession). If not, please ask and I'll try to do better