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From: Kevin McMurtrie
Subject: Re: Ignition Coil High Voltage Power Supply
User-Agent: MT-NewsWatcher/3.2 (PPC Mac OS X)
Date: Sun, 12 Jan 2003 06:54:55 GMT
NNTP-Posting-Date: Sat, 11 Jan 2003 22:54:55 PST
In article <firstname.lastname@example.org>,
John Larkin wrote:
>On Sun, 12 Jan 2003 05:36:15 GMT, Kevin McMurtrie
>>In article ,
>> Thoremail@example.com (P!erCer) wrote:
>>> I am constructing an ignition coil based high voltage power supply
>>>to power my lifter (I have posted here before). At this point, I am
>>>running into problems. My lifter somehow isn't getting the proper
>>>power to lift, even though the sparks can be adjusted to be upwards of
>>>two inches long. Please help.
>>>My basic system is: 12 volt battery running a distributor that
>>>switches the coil.
>>>A) Is the output of my coil AC or DC? How do I check? I want pure or
>>>B) Why doesn't my voltage increase when I put two coils in parallel?
>>>C) What do you predict the waveform of my output looks like?
>>>I have two ideas why my lifter isn't working. One person on this
>>>group told me the coil was producing AC, and that would mess up the
>>>ion behavior around the lifter. My belief was that the pulses were
>>>coming too far apart to fully charge the lifter (it functions as a
>>>Would it help if I half-wave rectified the signal going from
>>>distributor to coil? Two wires go from the distributor to the coil,
>>>then one from coil to ground. That is why I suspect AC...though why
>>>would they need a ground?
>>>Thanks a bunch,
>>The coil produces AC, kind of:
>> | Flyback
>>--- |||--- 0V
>> |_____|| Charge
>A car-type ignition coil will have an output that's a damped
>sinusoidal ring, and goes about equally positive and negative. There's
>a lot of capacitance in the system, some deliberate and some
>distributed in the windings.
>You can just hold a scope probe near some spark-plug wires to see the
The pulse looks like above unless a diode blocks reverse voltage through
the semiconductor driving the coil. On the cars I've seen, there is no
negative swing. There could be some ringing with older mechanical
distributors but the spark discharge on the first HV swing consumes most
of the power.
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