# ATOM Diy module

#### sign216

##### Member
Debe, how does this work? The electronic ignition units I'm familiar with, connect to both the points and the coil, using the points as a switch to fire the coil. Your unit appears to disconnect the points entirely.

#### shortbus=

##### Well-Known Member
Hi, I have a question about these 'Atom' modules. On the one page shown, there are different color modules, any idea what the difference is between them? It says ignition timing, how would the schematic change for different color modules? And thank you for posting the schematic!

##### Member
Hi, I have a question about these 'Atom' modules. On the one page shown, there are different color modules, any idea what the difference is between them? It says ignition timing, how would the schematic change for different color modules? And thank you for posting the schematic!
The values of R2/R3/C1 will change the delay between the primary voltage reaching (?)volts and Q1 cutting off, which causes a spark in the secondary.
Spark-timing is thus set to a specific time after the motor reaches a specific position (and velocity.)

#### debe

##### Active Member
They are wired across where the points & condencer go. The module polarity will depend on the ign pulse polarity, if it doesn't work connected one way just reverse the conections of the module. The switching transistor must be insulated from the heatsink when constructing, to allow reverse conecting. Magneto condencers can vary in capacity .15 to.25uf & are atleast 400v. Wrong values will cause point burning.

#### debe

##### Active Member
For those interested there is quite a lot about Atom ign modules in US Patent 4,163,437 Aug 7,1997. That's where I initialy found the circuit, but there was no component values. And the switching transistor was custom made for Atom. For reliability i still had to add the Mosorb 15KE200A (IN6303A) 200v spike protector.

#### dr pepper

##### Well-Known Member
Like it, a few scrap box parts and a working mower, I saved that in my archives.

I had a mower with a substantially bodged ignition, was done to cut one lot of grass but ended up doing 10 years.

#### tysman

##### Member
how do i adjust resistors to make brown or yellow module like the Nova 2 or equivelent?

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#### cowboybob

##### Well-Known Member
Welcome to ETO, tysman!

This is a rather old thread.

You are more likely to get a response if you start your own, new thread, referencing this one if you like.

#### tysman

##### Member
how do i message debe?

#### debe

##### Active Member
This is the circuit of a Brown module that I pulled apart. Have not seen a Yellow one to dismantle yet.

#### tysman

##### Member
thanks for the schematic, is the brown module same as yellow? also will the brown module work with saws that rev 7,000 - 10,000 rpm like the nova 2 and rapid fire does? im adding these modules to homelite saws like sez or XL12 and an XL76 that has dead blue coil that im replacing with points coil and adding module to get spark

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#### debe

##### Active Member
Got no idea if they are the same as I haven't had any to pull apart. Those modules here in Australia if you can get them cost around $30 each. Ive already spent$90 on modules pulling them apart to find the values.

#### tysman

##### Member
ok no problem, so how are you getting values are you measuring the transistor or disassembling the transistor to measure values?

#### debe

##### Active Member
The three modules I pulled apart were constructed the same, using the same switching transistors. The only variations I could see were different resistance values & slightly diferent capacitor values. I mainly stuck with the Red module circuit as it suited my Lawn mowers & Outboards. The modules are getting hard to find now as its 10Yrs since they stoped producing them. The Nova modules proved to be unreliable on some outboards.

#### tysman

##### Member
I see now, the black area was a film resistor on a ceramic substrate. I wonder if the Nova is similar. I might wait till one of them quit working then I will take it apart if I find anything will let you know. For now I will build the brown module and test hopefully it works like the Nova 2 if I cant find that tranistor is there an equivelant that will work?

#### debe

##### Active Member
I have tried quite a few transistors, but reliability was an issue. I found the 2SD1071 was the most reliable.