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ATOM Diy module

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
You want electrical isolation and good thermal resistance, My favorite is the Sil-Pad because it does not require heat sink grease. My second favorite is kapton. I'm not crazy about Mica. You want ow thermal resistance on the back of the TO-220 transistor.

Kapton tape can surely help in the construction. The Silicone adhesive is good to about 200 C. It's also available with an acrylic adhesive. I have both tapes at home. I used the Silicone adhesive regularly at work (semiconductor research lab).

You could probably get away with a larger piece of Kapton tape with silicone adhesive that essentially fills the C-channel and some thermal grease on the other side.

If you read into the details, I would get a TO-220 mounting kit instead of a nut and lockwasher. The bellveille (dome shaped) washer used is superior to lockwasher. see: https://en.wikipedia.org/wiki/Belleville_washer
 

debe

Active Member
SIDE VIEW.JPG TOP VIEW.JPG It doesn't mater what shape the capacitor is, I used the smallest I could find at the time. Heres the dimensions.SIDE VIEW.JPG TOP VIEW.JPG
 

debe

Active Member
This is what voltage spikes the unit has to deal with just at cranking speed. The Villiers coil doesn't have that high a voltage. But the Wipac is mutch higher & this was the reason for the Mosorb as it would eventualy destroy the module. This is why Nova modules fail on some ignition systems. Note these 2 ign systems are diferent polarity.VILLIERS.JPG WIPAC.JPG
 
The Mosorb is there to clip high voltage spikes. I found some Ign coils would destroy the switching transistor. So its there for reliability, I did not think $2 each was that expensive.
Now I will wait 2-4 weeks one stop shop for 10 complete RED ATOMs

Note: I contacted the seller to swap in 1.5K Ohm 2W resistors looks like I selected 1.5 ohm

upload_2017-6-19_0-19-56.png
 
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You want electrical isolation and good thermal resistance, My favorite is the Sil-Pad because it does not require heat sink grease. My second favorite is kapton. I'm not crazy about Mica. You want ow thermal resistance on the back of the TO-220 transistor.

Kapton tape can surely help in the construction. The Silicone adhesive is good to about 200 C. It's also available with an acrylic adhesive. I have both tapes at home. I used the Silicone adhesive regularly at work (semiconductor research lab).

You could probably get away with a larger piece of Kapton tape with silicone adhesive that essentially fills the C-channel and some thermal grease on the other side.

If you read into the details, I would get a TO-220 mounting kit instead of a nut and lockwasher. The bellveille (dome shaped) washer used is superior to lockwasher. see: https://en.wikipedia.org/wiki/Belleville_washer
Thanks for power and thermal joints I prefer true ITW Square cone washers. No knock offs!
https://www.wclco.com/wp-content/uploads/tf22-2.gif
http://www.shakeproof.com/products/threaded/preassembled-fasteners.html
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
I'm always buying weird fasteners. Are they a good source? I'm in the US.
The last odd fastener I purchased was from the uk. Something like M1.5-3 or some such non-sense.
 

dr pepper

Well-Known Member
Most Helpful Member
M1.5 x 3 would be a super course thread, the pitch is bigger than the diameter, didnt you mean 0.3?
Here in the Uk our toolboxes need 7 or 8 kinds of spanner, or a pair of shifters.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
dr pepper

OK, 100 of these: https://www.accu.co.uk/en/cheese-head-screws/6434-SFE-M1-2-2-4-A2
M1.2 x 2.4 L 0.25 mm pitch Cheese head Stainless Steel These are actually bridge screws for a one piece bridge for eyeglasses.

Here in the Uk our toolboxes need 7 or 8 kinds of spanner, or a pair of shifters.
I know, it get's annoying sometimes. back in the day, engine parts were English and body parts were metric. Disk drive had both metric and English tapped mounting screws.
i bought a 2 piece shaft collar recently and the bore was English and the set screw was metric. I got burt when i tried to order a hunk of drill rod and I really needed 7/8 instead of 22 mm.

e.g.
Size: 22 mm Decimal Equiv: 0.8661 and 7/8 = 0.875; It was tough measuring even with a digital caliper.

Then i was trying to find a screw for a spacer because I wanted to put a TV tuner on DIN rail. the manufacturer couldn't tell me. It may have ended up to be a #3-48 English screw. One hardware store nearby has "gun screws" which come in really weird sizes and lengths. I still haven't mounted it.

I ordered some Hi-lo screws for plastic.

I've never heard the term "shifter" before. It must be an adjustable wrench.

i still don;t have the right cross point drivers such as Phillips, reed and prince, Pozidrive, the Japanease phillips screws etc. i do like torx and the square dribe screws.

Clutch head I haven't seen since TO-3 transistors in car radios used them.

I want to size some 1/4" turn fasteners. That's a royal pain.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
I'll be the devil's advocate here. Why? The darlington construction may keep C from being the metal tab. See: https://www.onsemi.com/pub/Collateral/TIP140-D.PDF. It's a darlington, no no mention case is tied to tab. For a 2N3055, the case ties to C is mentioned. http://www.mouser.com/ds/2/308/2N3055A-D-43225.pdf

Usually C is the case. Easy enough to check if I someone has one. Here, I THINK it's isolated.

The terminal looks like it's made from an Aluminum M-F spacer with another M-F Nylon spacer.
 

debe

Active Member
The Assembly does need poting as it wont survive vibration. KISS the tab is electricly connected to C on all of these transistors we are using, in the above picture the tab is part of the circit to ground on this particular outboard. UTC are the same specs.
 
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tysman

Member
OK so I installed the module in my chainsaw it runs and idles high speed seems weak but might need adjusting. The only problem is it works with switch in stop position anyway to make it work in run position? The switch beeps in off position don't know why there built that way
 

tysman

Member
I can't mount my transistor on metal it loses spark is it OK just to heatshrink everything or will it get to hot?
 

tysman

Member
Ok so I use that between the transistor and aluminum. So I can mount aluminum to metal without it conducting through using same hole? Would like to use same hole in transistor to mount to aluminum heatsink and to metal of saw
 

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