Roll Your Own CDI

[ducedave]

Thank you -can you post a pic like that of one that would work for me-I can't read schematics if you could I would be vary thankful

 

[rohmell]

Thank you -can you post a pic like that of one that would work for me-I can't read schematics if you could I would be vary thankful

Go ahead and build the simple CDI and give it a whirl, see how it works for you. You can add an RC network later for adjusting the timing.

 

[ducedave]

Go ahead and build the simple CDI and give it a whirl, see how it works for you. You can add an RC network later for adjusting the timing.

Ya that's a starting point-I'm running with a reed and a higher compression heed and expansion chamber some retard would be a GOOD thing-I guess no retard is better then too much advance-I'll try to find a pic of a RC network in the earlier thread posts thank you rohmell

 

[skrew37]

Parts are not to scale, but more or less like this:

I'm finally going to build this tonight. One question, I'm having deciphering which resistor is which? Is the 18ohm or the 82ohm on the bottom in the pic? Thanks.

 

[skrew37]

Correct me if I'm wrong, but I think the 82ohm is going to the black wire.

 

[rohmell]

Correct me if I'm wrong, but I think the 82ohm is going to the black wire.

Yes, 82 ohms (grey, red, black) is the bottom resistor, going to the black wire.

 

[rohmell]

I'm finally going to build this tonight. One question, I'm having deciphering which resistor is which? Is the 18ohm or the 82ohm on the bottom in the pic? Thanks.

Post some pics, we would all like to see!

 

[skrew37]

I will. I figured out the value as soon as I realized it was a grey band and not white. I didn't get my PCB yet (universal) but I'm thinking of trying the "pill bottle" method first. That and I'm impatient. Anyway, if I don't get too distracted tonight, I'll try to put one together and maybe even test it tomorrow. Now to find a pill bottle or other ingenious container....

 

[Kristof]

I got this ignition coil for free, will it work with a jaguar "homemade" setup?

 

[ducedave]

I got this ignition coil for free, will it work with a jaguar "homemade" setup?

That's for a car don't know if a HT could energize the primary in a coil that big-cars are 12v.and have much more amps. I wouldn't run it for long if it did work it could burn out your cdi I would think.

 

[rohmell]

Ignition coils designed for cars will work, I am currently using an ignition coil from a Z31 300ZX with my CDI.

 

[Kristof]

Where can I get one for cheap that will work?

Never mind.... Rohmell answered my question.

 

[Kristof]

Rohmell, could you send me schematic of what I need to build?
Can you send me a list of parts too?

Are these parts available at Fry's electronics?

 

[rohmell]

There are schematics and parts lists all over this thread, and PCB layouts, too. I don't know if Fry's carries everything that you need, but there are links to eBay listings for SCRs and capacitors that might be hard to find locally.

 

[Kristof]

There are schematics and parts lists all over this thread, and PCB layouts, too. I don't know if Fry's carries everything that you need, but there are links to eBay listings for SCRs and capacitors that might be hard to find locally.

Thank you.

 

[Greg58]

I was wondering if anyone has bought a lot of the scr's on e-bay and would like to sell a couple?

 

[rohmell]

For $8.95 you get 25 SCRs:
25 PCS GE C106D1 C106D 400V 4A SCR RECTIFIER DIODE BOX7 | eBay

The point is, for 9 bucks, you get 25 SCRs, if you buy a few from someone, and add shipping, etc. it probably will come out to around the same cost.

 

[Kristof]

This is what i got for free. Rohmell confirmed that it will be good to use.

BTW, What is the difference between stock black box and this, or any aftermarket, CDI?

 

[ducedave]

Parts are not to scale, but more or less like this:

so would replacing the 82 ohm. resistor with a potentiometer allow timing retard- and if so could a switched on off +ohm. resistor be used to have two different timing choices

 

[rohmell]

For a retard circuit, you would need a capacitor along with a resistor. The resistor would slow down the charging rate (delay) of the capacitor, until it reached the proper voltage for firing the SCR. The slowing down of the charging rate/delay would cause the timing retardation that you are looking for.