Spark Waveform

OK, first a little introduction to my measurements..... but don't worry

I won't be getting into the electrical characteristics of the waveform.

O-Scope:

An Oscilloscope is used to measure frequency and amplitude

in the time domain.  Usually, a probe attached to the O-scope input

to sample the signal of interest.

O-Scope probe:

An Oscilloscope probe is used in conjunction with an o-scope

to sample the spark plug transient without changing or distorting the spark waveform.

Voltage:

Voltage is the increase of potential from frame ground.

Frequency:

Frequency is how many times per second the spark transient occurs.

Frequency is also defined as 1/time.

I've posted two different spark waveform plots.  The first waveform plot

(spark#1) illustrates the overall wave-shape and was detected through a sensor loop

installed over the spark plug wire insulation.  This "loop" is very similar to the the sensor

used on a timing light to adjust motor timing.  The second plot (spark#2) was detected

by connecting an o-scope probe to the tip of a spark plug (center electrode).

The spark plug was grounded to the engine (chassis), but not installed in the motor.

Spark#1: y-axis is amplitude, x-axis is time

Spark#2: y-axis is amplitude, x-axis is time

This is the most meaningful waveform plot of the two.  This waveform shows

the peak amplitude of the spark right at the tip of the spark plug (electrode).

Interesting enough, the spark output out the plug is >1000 volts peak

amplitude and has a frequency near 4 thousands times per second with the starter

push button engaged (motor not running).