How do Atom Computer Ignition modules work?

[david-bartlett]

Tubs said it well.

X2

[legendre]

Then we’re just simply never going to have a meeting of minds on this. I stand by my claim that those holding the contrary position are mistaken, just as you stand by the converse.

Ultimately, only one school is correct – and time will tell, hopefully, which that is. If I am disproved, I will be the first to admit it – and I will trust that you gentlemen will be just as swift to do the same, if the circumstances are reversed.

For now, I’ve said all I care to – as I’m completely bored with and worn-out on the topic.

So.. back to my +original+ query.. lol!

What is the correct full-advance ignition timing, in degrees (or inches, millimeters of piston travel) BTDC for a Johnson TD20 or any other model based on the same powerhead? Is this simply not published anywhere?

[legendre]

Disagreements aside, I hope that we can all continue to work together to develop an inexpensive and simple DIY technique for producing the ‘Atom’ type modules. While it’s unfortunate that they discontinued production, the prices they charged were seriously marked-up.

Information strives to be free, and we need our "own" method of implementing this type of ignition solution. And debe and others have made great strides in this area.

[phil-b]

A year ago I tried laying out a printed circuit board for debe’s version of the module using free tools from
http://www.geda-project.org

But never reached result I was happy with (I think I was aiming at 1" x 1") — I’m a software guy, who has generally had a black thumb building things….

Using http://pcbshopper.com/ it looks like a 1×2 2-layer board might be $1 a piece.

Any EEs out there?

[The Boat House]

• This reply was modified 5 years, 6 months ago by The Boat House.
• This reply was modified 3 years, 2 months ago by The Boat House.

[jnjvan]

Advance curves for outboards are difficult to find, for reasons that Tubs has stated. Here is one that I have found. It is from a paper on the state of the art in outboard motor technology (1963). The paper was published in England by the Institution of Mechanical Engineers. It shows ignition angle from about 6 degrees ATDC at idle, to around 37 degrees BTDC at full speed. I would speculate that this is a representative ignition curve for a broad variety of outboard motors.

[Mumbles]

Did benchrascal’s original question ‘How Do Atom Computer Ignition Modules Work’ ever get answered correctly in the preceding ten pages and 95 replies? If so, I missed it.

[jnjvan]

The third post, where debe listed the patent for the device, is a pretty good answer. Patents are brutal to read and understand, but that particular one gives a very good description of the operation of the device.

JV

[legendre]

quote jnjvan:

The third post, where debe listed the patent for the device, is a pretty good answer. Patents are brutal to read and understand, but that particular one gives a very good description of the operation of the device.

JV

In short, the Atom modules draw their operating power from the output of the ignition coil primary winding (they borrow a little bit, not much, of what will eventually become the spark energy), and trigger (as in, fire the plug) based on a certain voltage threshold in the same waveform.

To be very simplistic, the module replaces the points. But whereas the points are commanded to open based on the position of the points cam, the module is commanded to ‘open’ based on a certain voltage – a voltage which is intermittent, but regular and repeating. Think of the shape of the rising & falling voltage waveform – sort of a hill and dale – as an "electronic cam" that triggers the module.

[johnyrude200]

jumping into this conversation, I recently renovated a 1975 15hp johnson with a pair of these atom modules previously installed. The motor was sitting up in the mezzanine of a marina for 20 years.

That said. there was 3/4 spark on cylinder 1, and 1/2 inch brown spark on cylinder 2. Since I am becoming familiar with the ATOM aftermarket product, I removed them to install a new ignition system. Is there an evaluation procedure to check these for performance as a single component?

Other than the charge coil and ignition coils, I guess it is just a matter of checking grounds on the other components?

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