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ATOM Diy module

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
Here's http://pickersyard.weebly.com/atom-universal-electronic-ignition-module.html a good reference to add to this thread. It does contain the module colors that were available.

Some differences are obvious. excessive RPM (chain saws) option and an easy start option, fixed timing, high speed)

Thanks for trying that transistor. I THINK I mentioned it in this thread long ago as a better choice.

I bought two from Oregon. I've installed one and want to put another in an ancient Tecumseh snowthrower. Tecumseh did make an electronic ignition module for it, but you had to change the timing with an insert in the flywheel.
 

tysman

Member
It just doesn't like the pheleon flywheels with the tighter magnet gap it works fine on the wico flywheels they have medium gap and usually came on saws with blue electronic ignition. Or I need schematic for orange module works with go kart engines 18,000rpm +
 
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tysman

Member
These modules don't work I hate to say it the engine will run just no full throttle so far only had success with 1 saw out of 3
 

tysman

Member
That works with saws? I tried it it seamed better rpm but then coil died in saw could module kill coil or did my coil just die due to old age saw started and reved then wouldn't idle for long then died then after few tries no spark at all till I swapped coil now runs good on points again
 

debe

Active Member
Theres no way a module or points are going to kill a coil. Cranking an engine with out a spark plug or a spark gap, will damage a coil. Or just old age.
 

tysman

Member
OK was thinking maybe my switch might of sent some feed back. Cause when I turn off engine and switch from points to Module maybe there's a charge built up and sends back to coil the switch I used is an ON/ON DPDT, coil is in middle of switch
 

tysman

Member
i took apart a Nova module not much in there an SCR and a IC which is for timing is my guess and a diode and 3 leg tranistor but all this stuff is small smd parts on a board
 

tysman

Member
i wish you had schematic for orange module i need timing advanced. it has to do with either gap in flywheel to tight or width of magnet in coil i didnt have original magnet for black coil i bought so used the narrow magnet that came with blue coil that burnt out and had success with that 1 saw with brown module maybe magnet was key. i do have another magnet from a blue coil that i will try in my other saw see if thats the key or if its flywheel gap
 
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tysman

Member
So I put blue coil magnet next to stock black coil magnet there's difference on where the flywheel will start on its rotation. And its a difference of half inch or so and blue coil magnet is square at one end instead of rectangular. Will try it out when new coil comes
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
On a snowblower that I have, it can be converted to electronic ignition by Tecumseh, but I'm not sure it's available anymore. I do have the flywheel insert that changes the timing. I plan to put a Stens module in there. I might have to try both. I have to replace the throttle control first. I need to sand paint the used one.
 

tysman

Member
the stens module works make sure its mounted somewhere where can get cooled by a flywheel and gets good ground use heat compound to disipate heat they get really hot. funny thing is went to a service depot to pickup a oregon module since atom wont give rpm needed cause its an xl76 58cc saw, and she says the best module was Atom brown but cant get them anymore, ironic that is what im building lol
 

tysman

Member
so far so good used magnet from blue prestolite coil in my black coil didnt change flywheel it works on points revs up nicely so if i get my top end on saw with brown module thats the key is that magnet to use. if you dont use magnet and just use stock one your black coil came with the saw will run just no rpm it goes to certain point and thats it so cant cut wood like that. obviously other saws will probably work better and not have to change anything just add module so maybe homelites are the finiky ones
 

OldFogeyUK

New Member
I've done some experiments with the basic 'Brown' circuit on a home-built outboard motor using vintage J.A.P. Model '0' two-stroke with a Wipac magneto.
All testing was done with the motor in water to provide a realistic load.
I used values as follows: R1=1K0 1Watt, R2=2K2, R3=1K0, Q2=BC337, however I chose a TIP162 for Q1 which avoids the need for the shunt suppressor.
I wired the module into the ignition system with a two way switch so I could switch between contacts and condensor, or electronic.
Initially I used C1=0.47uF, and the module worked reasonably well, but was not significantly different from contacts and condenser. Notably, starting was more difficult and when running at slow speed or idle the engine would stop unexpectedly. It was always reliable at low speed when on contacts.
Changing R2 to 4K4 and R3 to 2K2 reduced the advance by making C1 charge more slowly, and it made starting easier, but high speed running was no better than contacts.
Changing C1 to 0.1uF advanced the ignition and gave significantly better high speed running than contacts. But C1 still needed to be a higher value to reduce the advance at idle and to aid starting.
I reverted R2 and R3 to 2K2 and 1K0 and set about testing different values for C1 from 1uF to 0.047uF.
I couldn't find a single value that worked sufficiently well at both extremes. It was one or the other. I considered adding a switch to add extra capacitance for starting but decided against it because the actual voltage on C1 is indeterminate and at some points in the cycle is negative. Having another capacitor with unknown charge suddenly appear in parallel could cause undesirable effects.
For experiment I added a 10K Lin pot in series with a 0.47uF cap and put them across C1 (0.1uF), thus providing some variable extra capacitance to manually adjust the timing.
The results were spectacular. Really easy starting and smooth idle with VR1 at 0K, very smooth running through the range by increasing VR1 while opening the throttle, and much better high speed running with VR1 at 10K when the additional capacitor has next to no effect.
It's all manually operated at the moment, but I plan to rig this to the throttle cable via a adjustable linkage to provide an automatic advance/retard for optimum timing at all speeds.
 

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