[Top] [All Lists]

[Shop-talk] Oscilloscope on my car's ignition

To: Shop-Talk <>
Subject: [Shop-talk] Oscilloscope on my car's ignition
From: Doug Braun <>
Date: Tue, 18 Dec 2012 23:44:37 -0500

I had borrowed an oscilloscope from a friend, so it occurred to me to hook
it up to the primary ignition circuit of my '31 Ford. I never realized that
so much information could be gotten from the waveform!

Here is a video of what I saw:

Has anybody else ever scoped an antique car ignition? The waveform doesn't
look like the sample waveforms I have found on the web. The main difference
is the fast ringing during the burn time. The intensity of the ringing
randomly switches between two levels, as the engine misfires. Has anybody
ever seen that?

I thought that maybe that ringing comes from the car's non-resistor plugs.
But after this I hooked it up to my '72 Spitfire, which of course has
resistor plugs and wires.
That high-frequency ringing during the burn time was present on that car,
too.  Any idea where it comes from?


<Prev in Thread] Current Thread [Next in Thread>