May 15, 2015 at 11:02 pm #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.
Topics: 32May 15, 2015 at 11:44 pm #16063
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?
US Member - 1 Year
Topics: 121May 16, 2015 at 12:18 pm #16095
DEBE, What is the minimum voltage rating for the . 47 uf capacitor. I want to keep it small.
Canada Member - 1 Year
Topics: 157May 16, 2015 at 12:34 pm #16096
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.May 16, 2015 at 8:06 pm #16132
I’m not Debe, but..quote mercuryman:
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.
US Member - 1 Year
Topics: 46May 16, 2015 at 10:34 pm #16143
My thoughts would be the zener would cap the voltage being input? Just my uneducated calculationed guess!May 16, 2015 at 10:44 pm #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.May 17, 2015 at 7:11 am #16190quote debe:
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. 😉
Topics: 23May 18, 2015 at 8:27 am #16306
Will these modules work on 1930’s opposed twin cylinder models with single coil?May 18, 2015 at 2:43 pm #16344quote WeedlessDrive:
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?
Topics: 30May 20, 2015 at 5:37 pm #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
Topics: 23May 21, 2015 at 3:12 am #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.May 21, 2015 at 3:56 am #16570
Not Gary..quote WeedlessDrive:
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!
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