modified cdi and cr 80 coil
- Thread starter damo99
- Start date
Ok, people seem 2 want more jumpers so I'm putting together another variation on this CDI with either 2 or 3 A jumpers on the initial firing point, 1 jumper between kathode & gate & 3 B jumpers on the timing retard. I'll test for a couple of weeks & if all good I'll post schematic & results. Cheers
Hi, 4 those trying 2 get the exact Jaguar circuitry, try replacing 27 ohm pulldown resistor with an 15 & 1 ohm in series, the 390 ohm between kathode & gate with 470 ohm & the 620 ohm in the timing R/C network with a 760 ohm. If someone could put a timing light on & check the timing curve against his I think it'd b pretty much in the ballpark. Cheers
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I just checked the pic Drewd posted (thanx) in roll ur own cdi. It shows 390 ohm in series with 1K between kathode & gate. Both add on 0.47uf have jumpers 2 earth for 2 retard curves. I cant make out (on phone) the value of the resistor in top left corner above the 120 ohm add on that gives the 3rd initial firing point, maybe Drewd will identify but there u have it. This circuit is pretty forgiving of changes so dont hesitate 2 tailor 2 ur liking. Cheers
Cavi Mike
New Member
You're talking about this post and this image?
http://motorbicycling.com/showpost.php?p=298658&postcount=32
http://motorbicycling.com/showpost.php?p=298658&postcount=32
No, the image posted by Drewd on page 43 of roll ur own cdi. BTW, the resistor in upper left corner appears to be 220 ohm guys, so thats the complete circuit. I had run 1 with an 18 ohm pulldown resistor but prefered the more advanced firing of 27 ohm & have run like it 4 quite some time. I have recently added an RSE head which is pretty hi comp & havent had detonation but will try a cdi built to this spec & see which I prefer. Cheers
Cavi Mike, its the 9th post back from the end of the thread. It is difficult 4 me, I'm totaly computer illiterate & post from phone. I lost phone the other day & had a hard time configuring new 1, then didnt know how 2 enable cookies so couldnt log on 2 answer u, sorry mate. When I went 2 school I dont think the school even had a computer, let alone students. Cheers
crmachineman
New Member
You're talking about this post and this image?
http://motorbicycling.com/showpost.php?p=298658&postcount=32
Excuse me Cavi Mike, this is interesting; is this some type of amplifier to boost the input to the coil? Looks really cool. I just ordered a DC fired race CDI for scooters and such to run my 66cc unti. I will run a small 12volt battery in a rear compartment to power the ignition. Are you guys essentially building your own CDI ?
Thanks
Yes, its a CDI, the 1 shown in that pic is not the CDI this thread was created for, go back thru this thread (page 17, 6th post, by Headtrauma, posting 4 Ivan H) for the schemtic & tips on modifying 2 suit ur own needs, or go to pge 43 of "roll ur own CDI" for schematic (note, the redrawn schemtic has 1 small error in the scr's kathode circuit), pics of both sides of the board & layout. Perhaps someone computer proficient could lift them over 2 this thread. I'm not, I had 2 snail mail headtrauma the origonal hand drawn schematic to get it posted. Cheers
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Ok, I thought I'd revive this as it an integral part of getting the power/smoothness I've got from the reed app that I have posted development of in the thread "Reed Kit" in the Hi Performance Tips section. This cdi will run fine as is, a little more advanced than the Jag, the retard kcks in at about same. To bring 2 Jag spec u need 2 reduce 27ohm pull down resistance to 16ohm. Also add a 220 ohm & jumper 2 earth in parellel 2 the 120ohm. Outta phone screen, nother post
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In between the Kathode & Gate of the SCR u need a 1k ohm & 390 ohm in series. The resistor in the R/C timing network is increased from 620 ohm to 760 ohm to keep the retard curve kicking in @ same time. Either 1 off the 2 CDI's will give smoother, more powerful opperation, on any China motor. U will need an external coil, CR80 gives hottest spark. The schematic is on Page 17, 6th post, this thread. Cheers
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CroMagnum
Member
Keep in mind that posts per page are selectable in the UserCP, so "Page 17, 6th post" doesn't work when the entire topic is only 5 pages long. Maybe you should use the post number in the upper right hand corner as a reference instead. For instance mine is #195.
Ok, the origonal schematic is Post #166, this thread, by Headtrauma, posting for Ivan H, thankyou very much Headtrauma, or it still wouldnt b on here. If u want it to the Jag spec c post #193 & #194, this thread, I have posted those values. Either 1 works fine, or u can try changing values, the circuit is pretty forgiving, within reason. Cheers
dracothered
New Member
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Ok, so u've got jumper selectable 16 & 27 ohm pulldown resistance with the A jumpers in parralell. I ran my first 1 with 27 pulldown & 1k+100 ohm in series between gate & kathode. My second built (jag spec) uses 16 ohm pulldown & 1k+390 ohm in series between gate & kathode. To have selectable pulldown u also want selectable 100 ohm or 390 ohm to keep the timing of right. Good job. Cheers
the easiest way would b 2 have 1k, 100 & 390 in series with jumpers bridging both the 100 & 390. Then u could select 27 pulldown, leave the 100 unbridged & bridge the 390, or select the 16 pulldown, bridge the 100 & leave the 390 unbridged. Both would need the ability to be bridged but u'd only need 1 jumper as 1 would always b bridged & 1 not. I like how u've made the pulldown selectable, I hadnt thought of. Well done. Cheers
dracothered
New Member
Is the above layout correct for the CDI that I posted? What should be changed on it to fix it or make it more tunable?
Yeah, ur all good, just do like I said with the 1k, 390 ohm & 100 ohm with jumpers in paralell with thr 390 & 100 ohm. Im gunna do 1 like coz u've made it so u can advance the timing where with just the 2 A jumpers in paralell with the pulldown it only retards so u've made a lot more combinations possible. The charge caps r X2 type 275VAC polypropylene. The timing caps r 35V Tantalum. Note they r polarized, marked +, which must go to earth. Cheers
dracothered
New Member
Ok here it is with all the jumper and up dated parts...
