Roll Your Own CDI

Are You Going to Roll Your Own CDI?

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Has anyone made one of the illustrated circuits of an adjustable cdi yet? I like the simple one and I've seen some of the schematics for more complex ones, but I don't understand how to read electronic schematics. If you made one of the illustrated ones with a thermistor and some kind of adjusting mechanism I would really appreciate it :) Peace
 
rohmell said:
Can you post pics of both sides of your PCB, so that I can look and see how it looks?
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Here is my sloppy soldering job. Maybe that's why it won't work. OR it could be the main wiring to the engine. Today, I'll buy some appropriate connectors and hook it up nice and tight tonight. Then if it doesn't work, I'm guessing it's from my beginner soldering mess...
 

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skrew37 said:
Here it is. I haven't had a chance to test it yet, and I'm still trying to figure out a good place to mount it on my bike. I'll be running this to a CR80 coil. Wish me luck, as this is my first attempt at anything like this and thanks again rohmell for all your help. What's funny is that I finished the simple CDI plans just in time for the retard circuit to be posted. I'm sure with a little modification, I can get it adapted to this as well. Here are some pics. The capacitors were so big that the only container I could find that would work was a travel container for a bar of soap, which I have to paint to match...
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Here's a view of the top again, for reference...

http://motorbicycling.com/attachments/f50/38782d1312374070-roll-your-own-cdi-img_20110802_184620.jpg
 
skrew37
what value are the resisters the blue ones?- I think your W. are to high I have to change the scale on my multimeter with the blue ones
I've got the 1/2 W.
My coil came today weighting on the caps
going to have to find 18ohm and 82ohm resisters
 
Hey Rohmell for all the work you have done and are still doing, I did some work for you today. Opened my original Grubee GT-5 CDI box and here are some pics. Someone with your savvy and test equipment should be able to trace things out and get values for most components. Can't read the components because of the epoxy but it sure looks familiar to me from following this sticky. The covering on the cap came off with the epoxy. You can see half of the cap covering stuck to the coil. On the PCB I can see the scr, a diode, and a resistor and can easily guess which way the other components go. The PC board didn't have any epoxy stick to the bottom and I have tried a few combinations of the numbers in internet searches but no luck yet. If you would like to see this stuff for yourself feel free to PM me with your mailing address and I will shoot it off to you. My equipment for electronics stops at my DVOM and my soldering irons hehehe. Anywho, hope this helps.
 

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ducedave said:
That right the color tripped me sorry
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No problem. I was a little confused too when I ordered them. I made sure to get the right values, but it was weird when I got them they were blue. I had to go back and double-check to make sure they were right.
 
Ratchetbirds said:
Hey Rohmell for all the work you have done and are still doing, I did some work for you today. Opened my original Grubee GT-5 CDI box and here are some pics. Someone with your savvy and test equipment should be able to trace things out and get values for most components. Can't read the components because of the epoxy but it sure looks familiar to me from following this sticky. The covering on the cap came off with the epoxy. You can see half of the cap covering stuck to the coil. On the PCB I can see the scr, a diode, and a resistor and can easily guess which way the other components go. The PC board didn't have any epoxy stick to the bottom and I have tried a few combinations of the numbers in internet searches but no luck yet. If you would like to see this stuff for yourself feel free to PM me with your mailing address and I will shoot it off to you. My equipment for electronics stops at my DVOM and my soldering irons hehehe. Anywho, hope this helps.
Click to expand...

It's no wonder some folks have issues with the CDI boxes.
Some of those solder joints look highly questionable.
 
The caps came in the mail all I need is a 18ohm and a 82ohm resisters
so close ! my Dad told me he has some old radios and a vcr he's going to drop by the house, so maybe there will be one or both in there- radio shack didn't have them and the supply shop is in the next county zpt
 
ducedave said:
The caps came in the mail all I need is a 18ohm and a 82ohm resisters
so close ! my Dad told me he has some old radios and a vcr he's going to drop by the house, so maybe there will be one or both in there- radio shack didn't have them and the supply shop is in the next county zpt
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I ordered some from ebay. They were $.99 with free shipping for a pack of 10. So for $1.98 and free shipping I got 20 resistors... Just a thought...
 
My capacitors i was waiting on came in the mailbox today :D

Enough to make 5 CDI boxes :D

I'll make one tonight and pick up the ignition coil on the weekend if i get time.

If all goes well i'll be more than happy to pass on my 4 spares :)
 
impression said:
My capacitors i was waiting on came in the mailbox today :D

Enough to make 5 CDI boxes :D

I'll make one tonight and pick up the ignition coil on the weekend if i get time.

If all goes well i'll be more than happy to pass on my 4 spares :)
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Man that's cool of you dude!-I got mine in the mail a few days ago I like your aptitude rock on and good luck
 
Another note on ignition coils.
There are 2 types. Rising field coils and collapsing field coils.
Rising field coils are designed to fire whenever power is initially applied.
Collapsing field coils are designed to fire whenever power is initially removed.

CDI's apply power at the precise moment when the spark is to occur. They use a rising field coil.

Points style ignitions open the circuit (removing power) at the precise moment when the spark is to occur. They use a collapsing field coil.

If your home made CDI unit is working but something just doesn't seem quite right, the type of coil that you are using could be the culprit.

Each coil design has a different saturation time AKA dwell angle.
Match it up wrong and performance suffers.
 
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