Roll Your Own CDI

[ducedave]

For a retard circuit, you would need a capacitor along with a resistor. The resistor would slow down the charging rate (delay) of the , 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.

Thank you, capacitor along with a resistor after the gate before the resistors or after the 18ohm or the 82ohm ?now for the value's any thoughts
I was thinking of a pot 1/2W in the works as I don't have a pile of resisters as for a capacitor not a clue as to type or value ether
Thank you x7!

 

[GearNut]

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?

That is only the ignition coil, the device that multiplies the voltage. There are no electronic components inside it except coils of wire.

The CDI box that comes with the kits has both the ignition coil and the electronics inside it, all neatly wrapped up in a little black box which is easy to install.

 

[FarRider]

I try not to get involved with the drama, as brilliant as Jags CDI systems were he was not the most likable guy, that and the mods do power trip a bit.
Getting banned for not doing a search? Thats a new one.
I let them do politics, i just wanna ride.
FR

 

[ducedave]

rohmell I hope I'm not being a pain-thank you all for this thread and letting me piggy back on your technical know how- I will have my kid show me how to post pics when finished I'm trying to get a cdi up and running-I ran good at the Willow spring race and with the Grange race nearing well I hope to run even better with a two timing position cdi and hotter coil.
Again thanks for what ever info you can share

 

[rohmell]

This Circuit is Retarded!

This circuit is retarded, but you may have to experiment with the 560 ohm resistor and capacitor value:

 

[ducedave]

Re: This Circuit is Retarded!

This circuit is retarded, but you may have to experiment with the 560 ohm resistor and capacitor value:

DUDE! Thank so much I'll get started on it

 

[rohmell]

Whatchyall waiten on?

Wutchyall waiten on?
Where the pics?
Where the comments?
Where the observations?
Where the critques?

 

[ducedave]

I've started working on it having a little trouble finding 2uF.1000A.-18and 82 ohm. resistors as for the cap on the retard I would guess it would have to be > 560ohm. building it on a scrap on clip board-I'll see if I can get my kid to post some pics
P.S. NAMING IT "THE DESERT FOX "THANK YOU

 

[rohmell]

Ducedave, I wasn't directing any comments towards you. If you took it personally, I apologize for any misunderstandings.

It just that this thread has over 5000 views, and no one else is building any of these CDIs?

 

[ducedave]

Ducedave, I wasn't directing any comments towards you. If you took it personally, I apologize for any misunderstandings.

It just that this thread has over 5000 views, and no one else is building any of these CDIs?

O-no I wasn't thinking that-"THE DESERT FOX " is in your honer, for all the good help, calling a cdi a rohmell sounds funny but the WWII general Rohmell was nick named "THE DESERT FOX " so I was nick naming the cdi for you!

 

[skrew37]

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...

 

[rohmell]

WOW, very nice. Good Luck with it, it looks like a winner, those caps look big and efficient, looks like they will pass plenty of energy on to the coil, for a nice, healthy spark.

If you build more CDIs, maybe instead of having the capacitors side-by-side, you could have them end-to-end and the whole thing could be put inside of some PVC pipe with endcaps?

 

[ducedave]

Ronken 2uF 1000 DC 66Hz Capacitor 12-749363-10 >N4
Item condition: Used

Price: US $6.99

 

[skrew37]

Good thinking. Then maybe I could zip tie it behind my seat post and put some covers over it like an old board tracker's toolkit. Yeah...

 

[rohmell]

Ronken 2uF 1000 DC 66Hz Capacitor 12-749363-10 >N4
Item condition: Used

Price: US $6.99

If I am reading the specs correctly, it is saying 66 Hz is the max. frequency range. 66 Hz is 66 cycles per second, the same as 66 pulses per second, the same as 66 RPM. So, the maximum engine speed is 66 RPM with that cap. DON'T BUY.

Here's a pair of caps that will do very nicely:
ARCOTRONICS MKP C.4G Capacitors 1.0uf / 850v / 450vac | eBay

If you have more than one MB, or want to build to sell to others:
10 x 1.0 uF / 630 V. METALLISED POLY AXIAL CAPACITORS | eBay

If you want one and only one capacitor:
http://cgi.ebay.com/1-2kV-2-0uF-Pul...610?pt=LH_DefaultDomain_0&hash=item53e88fb8b2

 

[FarRider]

Does any one know how to contact Jaguar?
FR

 

[ducedave]

If I am reading the specs correctly, it is saying 66 Hz is the max. frequency range. 66 Hz is 66 cycles per second, the same as 66 pulses per second, the same as 66 RPM. So, the maximum engine speed is 66 RPM with that cap. DON'T BUY.

Here's a pair of caps that will do very nicely:
ARCOTRONICS MKP C.4G Capacitors 1.0uf / 850v / 450vac | eBay

If you have more than one MB, or want to build to sell to others:
10 x 1.0 uF / 630 V. METALLISED POLY AXIAL CAPACITORS | eBay

If you want one and only one capacitor:
1.2kV 2.0uF Pulse High Frenquency Snubber Capacitor HV | eBay

thanks for that I just book marked them any idea what value to start at with the cap on the retard? I have a hand full out of a old tv and can I run resistor in line to get a combined ohm? -by the way I have the only working reed valve I've seen on a ht big gain willing to walk you through that mod any time!
as always you have been a big help

 

[rohmell]

...any idea what value to start at with the cap on the retard? I have a hand full out of a old tv and can I run resistor in line to get a combined ohm? ...
as always you have been a big help

Start at 3.3 uF and see how the retard goes, and yes, you can combine resistors in series to get the required value.

 

[skrew37]

These are the markings on the poles of my ignition coil. This may be a dumb question, but which is which? Isn't the one with the green wire the ground? Thanks.

 

[impression]

These are the markings on the poles of my ignition coil. This may be a dumb question, but which is which? Isn't the one with the green wire the ground? Thanks.

yes green has always bee associated by colour with ground/earth, so if you only have 2 points of contact i would count it as the 'negative' side of the ignition coil.

I have a couple questions of my own too > see attached image.

If i can get an answer to these couple questions and can find myself an ignition coil i'll make one of these tomorrow