How do Atom Computer Ignition modules work?

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This topic contains 215 replies, has 29 voices, and was last updated by Avatar joesnuffy 2 years ago.

Viewing 15 posts - 31 through 45 (of 216 total)
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    debe

    Replies: 103
    Topics: 0
    #16061

    JoeCB it is in the circuit diagram as a diode, its not in the original photo of the parts as it was found necessary mutch later in my trials. It has taken a couple of years of trial & error to get the module to this stage of reliability. The biggest problem was finding a switching transistor that was a Darington type with sufficient gain & voltage plus capable of at least 6amp pulses. The protector diode came about as some ignition coils give too high a voltage spike, this would either damage the transistor or over heat it & cause it to shut down. Ken W I don’t think going to a lower voltage would help with a Nova module, It just wouldn’t work at all once you put the diode across it, & I tried it with both polarity. I wouldn’t have got this far if I hadn’t sacrificed a perfectly good Atom module to find the actual value of the resistors & the capacitor. The circuit came from the US Patent of the module, but theres no values given in the Patent. If any one wants to read about the module look up (US Patent 4,163,437 Aug 7 1979) Invented by 2 Australians. Probably one of the reasons they stoped making them in 2005 was most small engines now use CDI ignition & lack of sales.

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    phil-b

    Replies: 467
    Topics: 32
    #16063

    Debe,

    Another patent from the same inventors in US 4,911,126 (Mar 1990)
    The table at column 9, line 40 claims higher output voltage ("circuit 5") with the addition of a diode.

    Have you ever tested that out?

    mercuryman
    mercuryman
    US Member - 1 Year
    Replies: 340
    Topics: 121
    #16095

    DEBE, What is the minimum voltage rating for the . 47 uf capacitor. I want to keep it small.

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    chris-p
    Canada Member - 1 Year
    Replies: 2461
    Topics: 157
    #16096

    Debe,

    Just a thought, but have you ever considered selling these to the members that are not capable or making one, or understanding 80 percent of these posts, lol.

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    legendre

    Replies: 389
    Topics: 8
    #16132

    I’m not Debe, but..

    quote mercuryman:

    DEBE, What is the minimum voltage rating for the . 47 uf capacitor. I want to keep it small.

    That cap is fed from a 4:1 voltage divider, which is connected across the coil primary winding. So, the highest voltage the cap will see would be 25% of the maximum voltage developed across the primary during the flyback phase. An educated guess would put that voltage at ~400V, so the cap needs to withstand 100V +20% safety margin – call it 120V.

    However, he’s also using that transient suppressor diode across the primary, which IIRC clamps at 275V – so it +may+ be that the max. primary voltage is.. ~275V. In this case, the cap could be ~70V +20% margin, or ~83V.

    So you should be safe with 120V in any case, and as low as 83V with a 275V clamping diode.

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    jeff-register
    US Member - 1 Year
    Replies: 1074
    Topics: 46
    #16143

    Legondre,
    My thoughts would be the zener would cap the voltage being input? Just my uneducated calculationed guess!

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    debe

    Replies: 103
    Topics: 0
    #16145

    The capacitor I used was 100V as it was pretty small. The voltage across it cant be very high, as the max voltage the BC337 transistor can handle betwean Base/Emmiter (Vebo) is 5V. And Collector/Emmiter (Vceo) is 45V.

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    legendre

    Replies: 389
    Topics: 8
    #16190
    quote debe:

    The capacitor I used was 100V as it was pretty small. The voltage across it cant be very high, as the max voltage the BC337 transistor can handle betwean Base/Emmiter (Vebo) is 5V. And Collector/Emmiter (Vceo) is 45V.

    Yeah.. and if any of us had been observant enough to notice, the cap pictured on p.1 is marked for 100V,

    Probably could have saved a bit of guessing & figuring.. I guess. šŸ˜‰

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    weedlessdrive

    Replies: 151
    Topics: 23
    #16306

    Will these modules work on 1930’s opposed twin cylinder models with single coil?

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    debe

    Replies: 103
    Topics: 0
    #16311

    Only way to find out is try one.

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    legendre

    Replies: 389
    Topics: 8
    #16344
    quote WeedlessDrive:

    Will these modules work on 1930’s opposed twin cylinder models with single coil?

    If it works on a standard single-cylinder 2 cycle engine, it should work on an opposed twin.. as the opposed twin is really just a split-single, isn’t it?

    I mean to say, both cylinders approach TDC simultaneously and fire as one, off a double-wire coil, correct?

    Avatar
    garry-in-tampa
    Lifetime Member
    Replies: 3072
    Topics: 30
    #16529

    The mid ’30s Evinrude/Elto coils I am familiar with have a primary voltage around 5 to 8 volts with a secondary around 40,000 volts. The secondary is a single winding with each end firing a sparkplug. Grounding one plug wire doubles the voltage to the other. One wire being disconnected also kills the ignition to the other sparkplug. Both wires must be grounded when cranking an engine with the sparkplugs removed.

    Edit – The spark between the ends of the two high voltage wires should jump a 13mm gap

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    weedlessdrive

    Replies: 151
    Topics: 23
    #16567

    So Garry do you think the single wire module that is grounded would work on a 30’s motor? The module is made to replace points and condenser on a magneto ignition. I’m going to try it. I ordered a module just to see.

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    legendre

    Replies: 389
    Topics: 8
    #16570

    Not Gary..

    quote WeedlessDrive:

    So Garry do you think the single wire module that is grounded would work on a 30’s motor? The module is made to replace points and condenser on a magneto ignition. I’m going to try it. I ordered a module just to see.

    The firing geometry seems to be correct, so it’s probably down to the voltage and current requirements. Will be good to know for sure!

    Mumbles
    Mumbles
    Canada Member - 2 Years
    Replies: 4057
    Topics: 418
    #16574
    quote WeedlessDrive:

    . I ordered a module just to see.

    What brand of module? Nova II?

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