Performance CDI layout and schematic diagrams

[ivan H]

Hi KC, thats a great idea. U may need to put the ohm meter on the trimpot "out of circuit" to get an accurate reading, but with the trimpot's being a precision, close tolerance item (& having a linear resistance taper), u might only need to calculate the adjustment screw positioning for a 16 ohm setting once. They should all be ballpark close enough for the same setting to be near enough. After reading a few u'll know for sure if this is the case.
Going back to ur question about spark duration, a CDI produces a really hot spark (their use in 2 strokes took off as this helps burn off oil deposits), but it is of pretty short duration & there's nothing we can really do in regard to the CDI to remedy this. The spark is generated when the charge cap across tge primary winding is discharged causing the built up magnetic field to colapse, so probably coil design more than anything affects duration. Something I need to look further into. Cheers

 

[Huffydavidson]

KC , how's those boards coming along. Kinda seems like a SLOW & COSTLY way to go. Just finished up
CDI #25 today. Protos work fast as He!! for me and then I set them in Easy Cast. No failures , repairs, no callbacks. Burns out, O'well their just gona have obtain another one . YEA!!!
Just like the stock ones.

 

[KCvale]

Hi KC, thats a great idea. U may need to put the ohm meter on the trimpot "out of circuit".

So probably coil design more than anything affects duration. Something I need to look further into. Cheers

I can just solder in the resistor and pot first and count the turns for exactly 16Ω for the combined circuit and go from there, nothing to it ;-}

KC , how's those boards coming along. Kinda seems like a SLOW & COSTLY way to go. Just finished up
CDI #25 today.

Well done HD, you are a busy guy building CDI's and I appreciate your help help with my layout.

Yes, creating a compact user friendly circuit design for volume production PCB's is very time consuming especially when your first batch of boards are defective.

The photo sensitive material on the board itself itself was bad, or maybe it's the developer fluid but I suspect the board as I put the leftover piece of the 4x5 board after making 4 PCB's in developer when never exposed to any light and all the protective coating washed away when none should have as that is what keeps the etched part from removing the copper under it.

No biggie, it is not like I am in a hurry or this is job one, I build bikes and swamped, but I contacted Mouser yesterday and they sent me an RMA for whats left of this board kit and already a free new one on it's way ;-}

I found out why the 5 coils didn't get here, turns out they did via USPS and my mailman marked them REFUSED, meaning he claims a human refused the deliver, NOT!

This isn't the first time I will have to have a talk with my US postal moron about poor service but I have nothing but praise for both my UPS and Fed-Ex delivery guys, my shop is in the very back of the house and they know to just carry everything all the around here and both like to hang around for a minute to see what bikes I am working on ;-}

ANyway I ramble, I am going to try a section from another PCB in the kit before I box this PCB kit up for return as it may have just been one bum board.

 

[SKY120]

Update!! Got the 1% resistors in and soldered up a board... engine fired right up!! Now i can go ahead with my redesign of the board and put my cnc router to work making some pc boards!!

Thanks for all the help!!

 

[Huffydavidson]

Ata boy , we knew you had in you. Sky120 a "NEWBIE" did it. YEA and the crowd goes wild .

 

[ivan H]

Hi KC, yes, u can read direct off the completed board, just make sure u connect ur multimeter with the red + lead to the SCR's cathode end of the resistance & the black, common lead to ground to read it. A resistor is non polarized & so the meter can correctly read it being connected either way round, but in circuit is another matter. Hooked up around the other way u'll get a very wrong (very low) reading due to current (from the ohm meter) flowing thru the circuit. But I'm sure u'll be right with it.
Well done Sky120. I'm not sure wot caused it not to work because in reality, a resistor is a resistor regardless of type (tho different types are definitely more suited to certain applications than other typed) & will still work so long as the wattage rating isn't exceeded (they burn up). I bet it made u happy to hear it fire up. Cheers

 

[KCvale]

So how does the performance compare Sky? Or have you not had enough time to ride it around and adjust it yet?
That's going to be my problem when I get some built, 2-stroke bikes and time to test them on.

What are you going to use the CNC router to do? Shape you some nice 'proto boards' or whatever they are called?
That would sure be a cool to have when cutting out a bunch of boards from one bigger piece of material.

Hi KC, yes, u can read direct off the completed board

(smiles) I know Ivan, and save your cell phone internet thumbs, I don't need 'Beginner Meter Operation 101' classes, I have the proper tools and know how to use them ;-}

http://www.harborfreight.com/5-in-1-digital-multimeter-98674.html

The bells and whistles I haven't even tried, I got it for the range and precession as far as a $45 meter will do which for me is enough for most things I do.

 

[ivan H]

Just trying to help KC, which was the whole reason behind wanting the schematic & layout up here. An elaborate meter isn't needed for most things. I prefer US made "fluke" meters, but out of the 1/2 dozen odd meters that I have, my cheap old digitech analogue meter has the highest input sensetivity, nearly double that of all the much more expensive meters, meaning its capable of more accurate reading on related scales. A cheap little meter is invaluable& I think everyone should at least have access to one for the electrical side of there motorized bicycles.
It'll surprise me if Sky120 doesn't notice a difference straight away. Iif nothing else everyone I've had anything to do with using one notices smoother operation regardless of settings. Cheers

 

[KCvale]

It'll surprise me if Sky120 doesn't notice a difference straight away. If nothing else everyone I've had anything to do with using one notices smoother operation regardless of settings. Cheers

I expect every engine will run better and smoother with of any of these better ignitions including Jags as well.

I also agree everyone needs a multimeter, even just an $8 Radio Shack one, I just like easy to use quality tools is all.

 

[Huffydavidson]

BUT,BUT,BUT,BUT , I got mine for free at Harborfeight, doesn't mine count.
I even BUMDED a ride to go get it. And if your motor is true & balanced it WON'T fell anymore SMOOCHER. LOL I don't want it to run SMOOCHER, but Racetrack
FFFAAAAASSSSSSSTTTTEEEEEERRRRRRR. SO, take the 4.7 and do what ever with it , and put in a 7.5 then the curve won't start if you can get there until 3,000 RPMs.
YA BOYZ WINDER UP TO BLOW OR WIN !! Said lightening to bolt .

 

[ivan H]

HD, I would advise against,,, as I said in email u will (most likely) see over advance as revs climb above the mid range, IMHO. The fact that u r seeing excessive head temps & running it rich to keep cool (as u indicated in email) with a Fred head, which (by all accounts) has excellent cooling capabilities is indicative of this happening. Of course its up to u if u want to, but perhaps warn others that it may over advance above mid rpm. (running rich to stay cool I wouldn't imaging is conductive to maximum power & revs)
I am working on a CDI design specifically for race application's, that will run more advanced than these & will provide a full 30* of advance (& not over advance at higher rpm), & wont incorporate the retard at higher rpm feature, but I wont put it out there until I am 100% sure that it performs as intended. I had made an LED type timing light to assist in the design of this CDI (& was intending posting the timing light schematic for the punters). Unfortunately LED's only respond quickly enough to graph the lower end of the range so I'm putting together a simple Xeon flash tube type light so I can properly graph the CDI. I will also post the timing light schematic in the lighting & electrical forum. It's simple, cheap to build ($10 max), needs no inductive pickup (which I wound for the LED type, phew) & is wall powered. Cheers

 

[ivan H]

I do apologise if the design of the CDI is taking too long, but I do have other commitments. Cheers

 

[Huffydavidson]

That's simply just not true . My temp was a little hotter BECAUSE when I stepped UP to the twin plug Fred head, the combustion chamber and compression increases well . I was running 6.0 head and know I'm running the 5.3 combustion chamber which probably puts me up around 13:1 compression and with high compression comes warmer temperatures . therefore jetting up and more fuel will bring it down and increase performance . After running my HD LIGHTENING with 1.0uf charge caps and a 7.5uf timing cap its running extremely cool I like a bat outta **** . The plug look great (brown) and there is no Denation rings on electro to either . No engine ringing , thumping or any other signs. The piston looks fantastic because my spark is so hot everythings getting burnt . IMHO its due to the way I build CDI's and set up my engine. Screems unbelievably fast up to 1,100 rrpms.

 

[ivan H]

Aside from the stator & hi tension coils having more of an effect on how hot the spark is than the CDI, or that a complete burn is possible with a Chinese CDI & single plug, how are u ascertaining spark energy & can u give us an indication of, or figure??
As to how u make the CDI's, I'm not sure wot u mean but the idea of the layout was to enable people with no knowledge of electronics or how the circuit works to follow the layout to build one, & if it don't work at first they could yell out & maybe we could find wot they did wrong (sound familiar).
If people choose to use a1.5uf, fine but if they have no electronic knowledge it would be best if they were aware of the possible ramifications.
Using a 4.7uf timing cap it'll advance to around 28* @ 4,456 rpm. With a 3.3uf it'll advance to a bit over 30* (32?) @ 6,346 rpm, which many think is about all the advance u want.
It commonly believed that the Chinese CDI over advances at higher rpm. (both these CDI's advance due to the magneto voltage increasing as rpm increases). Wot isn't so commonly know is that the Chinese CDI doesn't keep advancing without limit. It advances to a point (no I cant tell u exactly where), & then will advance no further. It is (due to the circuit design), impossible for it to exceed the SCR's design limits due to increase magneto voltage.
If u use a 1.5uf timing cap it'll keep advancing unchecked up to 13,961 rpm, so the possibility of over advance is, IMHO, very likely, only with this design u may well exceed the SCR's design limits. If u use a 3.3uf it'll rev over 10k but not see more than 32* advance, & not have to worry about exceeding the SCR's design limits.
Cheers

 

[Huffydavidson]

Yes this true that it was late a simple enough for anyone to make one with the reason why the very first I built didn't work was in all of your instructions on this thread to build one you left out the most important detail for the unexpected , and that was the fact that the time in cabs are polarized and directional . That was your lack of instruction . As far as the design limits of the SCR , here's what I have regarding that tissue . This past Monday morning I called DiG-key regarding your posting last weekend. The tech I spoke with was extremely hopeful knowledgeable and I understood the design because he had done something somewhere in his life like we're doing . He informed me your feelings about the SCR failing are just that your feelings. The true fact is this, the manufacture of things like that usually rate them 40 percent lower than the failure point. And then gave me the part number for the next one up the line. I asked him if we're fail how long would it take and his reply was immediately under five minute time frame. So Ivan stop worrying about my design mods and get something else done.

 

[ivan H]

HD the timing cap polarity is & always has been marked on both the schematic & layout. To say it isn't simply is not true, & I don't want to get into an argueing match with u hear but it is the component manufactures that test their products to ascertain & then publish the design limits of. They do this for a reason, based on their testing experiences. Digikey, Mouser etc are suppliers of products manufactured by others. I'll be taking advise from the manufacturer's published specs over that of a sales staff.. Exactly which published design limit did he tell u its ok to exceed. I wonder if manufacturers would approve of them advising consumers in this manner,,, yeah mate, the manufacturer don't know sh*t, they just make em. We sell the f*ckers, course we know best. Did u get the sales staffer's name? Stick that up here & we'll shoot it across to digikey & see if he keeps his job.
Changing a cap value is not wot I consider a design mod any more than sticking a jumper on or off, & it doesn't bother wot cap anyone uses, I just like them to be aware of its possible effect. Cheers
LMAO

 

[Huffydavidson]

Yes the timing caps are marked and understandable for those that can read schematic language but for those who can't fit anyone can do it they do not understand and that was me in the beginning .You fail to clarify that you have to put the plus sign of the capacitor to the ground side of the circuit . You should go into your writings on this thread and edit that so that the easy doesn't know anything guy can do it . Like you said. And no I won't give up the tech that helped me. I not ever going to crap on someone that helped me. Argue with them definitely . Like I said, it would fail immediately or not at all.
200 miles and balls to the walls still rolling strong as He!!. I do need a chamber that's less restrictive thoughy, and advancement time reports a smidge more !!!!!

 

[ivan H]

Check post No.3, where it gets into construction. It clearly states that the + marked leg of the 4.7uf & 0.47uf tantalum caps MUST (emphasized in capitals) go to ground, or toward the jumper or edge of the board. Its always been there & wasn't edited in later. It was also said in the first couple of emails between us when the thread was started (I can post them???). Accurately predicting when a component will fail, whether used within or outside of design parameters has yet to be done. If ur guy has this insight wot is he doing working in supply. He's akin to God in the electronic component world. I'm late so I,ll get back to. Cheers

 

[KCvale]

I am progressing slowly as well but with a couple of days of rainy weather and finally a 2-stroke in the bay I had a chance to work on your evolving design Ivan and looking to get a test model ready this weekend.

After a couple of failed attempts to develop and etch a board I have it down again and produced a custom made circuit board to drill and propagate with parts!

The copper side of the board is coated with a photo sensitive film you expose to UV light then develop in a solution to wash away all the coating that wasn't protected from the light.

What you end up with is a single side copper coated board with a protective coating over the copper you want to keep like this.

The nest step is bath the board in warm Ferric Chloride to dissolve away all the uncovered copper.

That's a lot of copper to dissolve in the first one that came out for testing but I have already started modifying that design to cover more copper for the next ones because all you really want to do is dissolve away the copper between connections as the FC isn't cheap and it prolongs the process.

Note the RED in the PCB program I use is what copper will remain on the board.

Once all the unwanted copper is dissolved away the board looks like this.

It fits just dandy in the boxes I use on the top of stock CDI's anyway and it has a keylock ignition switch.

You may be wondering why KCsBikes.com is mirrored on the copper, that is because the circuit was designed from the top and since the board is semi translucent and the parts go on top you see through it and everything is aligned to follow the design to place parts like this.

Will it be better than stock or even work?
Will it allow for fine tuning of performance engines with easy adjustments?

Only time well tell for what it does for high performance so I'll need a tester but competence is high it will be better than stock even on a stock bike or with just basic performance mods like an X-chamber or jetting and well, it's pretty darn small and has a keylock ;-}

 

[Huffydavidson]

I hope there's room for my USB port so I can plug in to the dyno machine hook me up there is KC
LMAO