How do Atom Computer Ignition modules work?

[debe]

There is a small metal plate supplied with the original Atom modules for use as mounting & heatsink. The plastic is very thin between the transistor & the mounting surface to act as a heat sink. The transistor does need insulating as some ignitions require the polarity to be reversed. The Nova module & another Victa module use a metal housing as a heat sink.

[legendre]

quote debe:

There is a small metal plate supplied with the original Atom modules for use as mounting & heatsink.

I’ve never seen one. Did I miss it, in the earlier pics?

Can you provide some pics?

[debe]

No I cant post pictures here & the metal plate was in the Atom Kits I purchased originaly. They are in the first lot of pictures put up by Mumbles, they are used to mount the module if you aren’t screwing them down onto a metal area.

[legendre]

quote debe:

No I cant post pictures here

PM me for help on that, if you want to. I don’t seem to have any trouble posing images..

quote :

the metal plate was in the Atom Kits I purchased originaly. They are in the first lot of pictures put up by Mumbles, they are used to mount the module if you aren’t screwing them down onto a metal area.

Ok, but isn’t the (red, or whatever) plastic module case still sandwiched between the transistor body and the metal plate / engine? Or do they rely on that little brass ferrule to act as a thermal conduit? If so, that’s still a very weak thermal coupling.

[debe]

[/url]mg] Hope this works, its CRO wave form of a module using a BD651 transistor with a 120V Zenner diode across the C & E, all values are X10.

[ken-w]

I found that the TAB on the Darlington Device is the Collector connection. So when using the OMC Universal Coils and or the WICO Coils found on Scott Atwater it can be grounded to the chassis and the input from the coil can come into the Emitter connection.

[debe]

Same polarity for the older Seagull outboards with Villiers coils. How ever the later Seagulls with Wipac coil its the opposite.

[bjmullins]

I looked back and saw a question but maybe missed the answer. So how many modules would you need on an opposed firing twin? What about an opposed firing twin with modified coil (ie 2 modern OMC coil mounted on the orginal coil core)?

[Mumbles]

The modules purpose is to replace the points and cap. If the motor has two sets of points, two modules. One set of points, one module.

[Anonymous]

Thanks for sharing it here. According to me this module triggers off of the rising voltage waveform induced across the ignition coil primary?
I just can’t see any other way it would work there aren’t any magnetic sensors and the old points are gone, so they can’t be used as a signal.
How could you possibly establish correct and consistent ignition timing with this? Ep is a function of dB/dT, so the faster the rotor spins, the greater the voltage induced by a particular angle of rotation. If the module is set to always fire at a particular level, this would mean that the timing would advance as the engine speed increases.

[Author]

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