Looking for low-cost ignition analysis 'scope

[Lloyd Ferguson]

This is something I have been wanting to do for a while as I find it
fastinating that you can assess an engine's condition just by looking at
the spark waveforms.

I have tried he approach of using a "Lab" scope with the inductive pickup
from my timing ligt for trigger and a piece of metal over the coil in the
middle of the GM HEI distributor (this is the way the Heathkit analyser
works as well as other prfessional units I have seen). The interfacing is
not a problem, where I ran into problems is that the repitition rate of the
signals from the engine are so slow at idle that the scope does not have
enough persistance to keep the display on the screen.  When I did this
(about 10 years ago) I used a Tek 465 100Mhz scope maybe a lesser scope
would be better but I doubt it because the signal is pretty slow (600 RPM =
10 RPS /2 = 5 triggers per second).

As for the calibration, I purchased a manual for the Heathkit unit when I
was thinking about this and they clamped the pickup around the high-voltage
lead to the CRT for calibaration, not very usable on another unit. I was
going to address this if and when I got it working.

I have been milling around an idea of trying a cheap sound-blaster type
card with an analog input to digitize the signal and then using one of the
graphical audio editing packages to display it (perhaps doing the whole
thing on an old 286) any comments?

Lloyd Ferguson
CBC Engineering
7925 Cote St-Luc Rd
Montreal, Quebec Canada
Tel:   (514) 485-5340
Fax:   (514) 485-5364
Email: ferguson at srcing.login.qc.ca