Performance CDI layout and schematic diagrams

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SKY120

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Aug 31, 2013
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I reversed the leads and still nothing. Checker the mag with the stock CDI and I get spark so I know that's ok. Everything else is just normal resistors, diodes and caps... this shouldnt be this hard...I must be missing something. I did use a cordless drill to spin the crank on the engine so I know the mag rotor is going fast enough to get current to the circut. Here are he scr and charge cap I used, do these look correct?


http://www.digikey.com/product-detail/en/C106D1G/C106D1GOS-ND/1476376

http://www.digikey.com/product-detail/en/ECQ-UAAF105M/P14785-ND/2674017
 
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ivan H

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Oct 8, 2011
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Hi, yes, ur C106D1G is ok fot this. I think the G suffix shows it to be the run of the mill, general purpose item but either way its ok. Same with ur charge cap. X2 rating, 275VAC rating, 1uf. Thats ur huckleberry. I'll go back & check ur pic when I can see the phone screen better but things to check. Ur SCR has the writting side up so u can read it as it sits on the board. Diode polarity, the bar across the arrow heads point on the layout is the silver band on the diode body & must go in that way, with all diodes which are 1N4007 types. Tantalum caps are in the right way. They have a + marked leg that must go to ground, on all of them. This means the 4.7uf's + leg goes to the edge of the board where the wire link connects & the two 0.47uf's + marked leg goes to the jumpers which bring them into circuit by grounding them.
Next, ur coil. Is it a good coil. Is it connected correctly. Coil types with 2 spade connectors have a ground connection plus the connection to the CDI (charge cap). The coils ground connection is internally connected to the bottom end of both the primary & secondry winding & also to the core. The CDI connects to the other end of the primary winding & ur plug to the other end of the secondry. So the two spade connections must be properly orientated.
Wot is ur coil off???
I have seen simillar looking coils off like pit bikes or pocket bikes but they have a built in CDI (like a china girls) with the CDI being built into the rectangular section like where ur spade connections are. Some are 1 wire types & some 2 wire types which are fired by a small triggering coil in the magneto. These type couls will not work with this CDI unless u removed the CDI part & then properly connected thus one to it, which of course, could be done. I'll be home soon & check ur pic.
One more thing, a while back someone contacted me having built a CDI & was having trouble,,, it wouldnt fire his new coil. After numerous emails being exchanged & it still not working, I made one for him, tested it on my bike & mailes overseas to him. Ten days or so later he got it, thru it on his bike,,,,, & nothing. Another coil & both his & my CDI fired straight up. He had built it properly first time. Make sure ur coil works.
I believe Huffydavidson posted the ebay link for the CR80 coil just a few posts back, for a grand total of like,,,, 11 bucks. Seriously, unless u gave a coil off an MXer or simillar lying around that u r 100% certain works, when u order ur components to build ur CDI, pay the extra 15 bucks & order the CR80 coil at the same time. It has a considerably hottrr spark than the other 3 yamkawsuki coils for the 80cc range, & the chance of it not working out if the box are pretty remote.
Cheers
 
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ivan H

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One more thing, u deffinitely had the blue & black wire reversed on the board (check layout). If u spun the motor with the electric drill, u may have damaged the SCR. Remove it from the circuit & do the simple battery & bulb test I gave early on in this thread to find out for sure.
When trying a new CDI (after giving it the once over for mistakes 3
or 4 times), & ensureing it & ur coil r properly wired, it should fire first go, easier than ur China girl CDI/coil. Ask Huffydavidson. U dont need a drill. If ur motor was running before the CDI/coil change, & u only did that change, just fire it up normally to test. Dont ever try it without it attached to a coil which is attached to an earthed plug.
I realize u cant check it nornally as it not in ur bike, but it'd be easier if u left it til it was in ur bike & running first. Ni matter, can U show me the other side of the board with the blue & black wires visible out the side of the board (so I know which side is where?? Cheers
 
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KCvale

KCvale

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Feb 28, 2010
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How about just a known good coil number/make/model whatever that works best with this circuit as the coil is THE main thing and they have timing issues too.

When it is all refined I'll see if I can make time to DL another schematic program to lay out a real PC board you guys can just print it out on clear plastic to make real PC board and have to use those silly bread board things.
 
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SKY120

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Aug 31, 2013
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Tested the scr and it works fine according to your test. i'm thinking it could verywell be the coil. I just bought it off ebay so it should be good but I don't know. Ordered a CR80 coil this morning and will give that a shot when it gets in.. is there any reason one coil wont work over another one as long as they are just a plain ignition coil?
 
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ivan H

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Hi KCVale, the Honda CR80 coil is by far the best to use (& yes, they affect timing in a couple of ways, a little). The CR80 coil was kept the same over a wide number of year models. It has a straight bar type core right thru the middle with a mounting bolt hole at either end & only 1 spade connector (some will have a wire) for connectuon to the CDI so u cant go wrong. The black wire connects to one of the mounting bolt holes in the core (use an electrical "eye" connector). I dont have a part number at hand, (maybe Huffydavidson does). Again, Honda CR80 coil. Available as OEM from Honda dealers at probably rediculous price, or all over ebay. Huffydavidson got one for 11 bucks.
That would be a fantastic idea with posting a template for use with photosensetive board. The board is available everywhere (they have it in a number of small sizes at my local electronics outlet). If possible, could u keep as close as possible to the layout just so that if people run into trouble we can diagnos easily off a pic.
Thanks KCVale.
As to why some coils wont work, different types. Rising field & falling field, is one reason, there are also other possible issues. As I said earlier, unless u have a known good, suitable coil, order a Honda CR80 coil. We'll work on getting a pic of the CR80 coil up here, & maybe a link to (help,,, pleeeez, with both pic & link) an ebay vendor or 3, as prices vary a bit (well found at $11 HD)
Cheers
xct2
 
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rich4240

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Jun 6, 2012
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could u pls do a quild lay out or scamatic of your cdi witht the trimer i would love to make one
ivan H said:
Hi KCValue, thank you very much for that, much, much better. Ur question about the minature pots fits in perfectly with the next step I was meaning to describe;
continually variable initial timing setting between a point a bit advanced of the normal most advanced setting, thru to the most retarded setting by using a minature 25 turn 250 ohm vertical trim pot. As HD said, vibration can be a real problem (tho the multi turn pots cope with this much better). The answer would be to tune using the pot, then remove it without changing the position of rotation, then measure from to find the resistance across it & make up a resistor of the same (or as close as possible) value to solder in. (In a race type CDI I wouldnt want jumpers).
So, u wiuld need;
an 18 ohm resistor;
a 51 ohm resistor;
a minature, 25 turn, 250 ohm vertical trim pot.

The trim pot is a little plastic block with 3 connections (pins) exiting the bottom & a small screw head at one end on top.
U would replace the 16 ohm resistor with the 18 ohm. Remove the 220 ohm & 120 resistors & their jumper pins.
Now u will want to use the trim pot as a variable resistor rather than a divider so u will connect the (variable) center leg to one of the end legs. Use ur multimeter to work out which one to connect it to, so that u know when u turn the screw u know whether ur making the resistot bigger or smaller (with regard to the way that u r turning the screw).
The trim pot cam go on the board where one pair of jumper pins were with the 51 ohm resistor then connecting the trim pot to the cathode of the SCR (where the 220 or 120 ohm WAS, depending on which spot u use).
So now, with the trim pot at its full value of 250 ohms the initial firing point will be slightly ADVANCED of the most advanced setting (no jumpers on the 220 or 120 ohm resistors) previously available. (basicly increases the 16 ohm to 16.984 ohms).
With the trim pot at its smallest value of zero ohms, the initial firing point will be roufhly the same as if u had a jumper on both the 220 & 120 ohm resistors. (basicly decreases the 16 ohm to 13.304 ohms).
To read the value of the trim pot once u have found ur ideal setting, u will first need to remove it from the circuit.
To then make uo a resistor of the same value u can put resistors in series, which adds their values together, or in parallel (use an online calculator to make it easy, google parallel resistor calculator), or a combination of series/parallel to get the value u need if it isnt available.
I think I'd be inclined to try leaving the minature trim pot in circuit before making up a fixed value resistor as I really think it might handle the vibration. When u see how they're constructed u'll see wot I mean.
So hopefully u can all understand my description of wot u need to do. If not, give me a yell asking about wot u dont understand & we'll try & clear it up.
With regard to the timing cap for use with a high reving race type motor, I think that changing from a 4.7uf to a 3.3uf will be enough of a reduction to allow the kind of revs needed for a race motor but this isnt something I have tested. My motor is ported & tuned for a wide midrange power band for use with a shift kit & 8 speed cassette, so my CDI is set up with just a smidge more initial advance & just a tad steeper retard curve (small extra capacitance), to keep it on the pipe which has slightly longer header.
By the way, nice job on the key lock ignition there KCVale, nice looking bike also, wot we can see of. The 3 position switch for the timing caps isnt a bad idea either, for a daily ride type aplication. For a race type motor I think I'd first tune the CDI to suit the motor's requirements, then solder all components in properly, just to ensure nothing could go wrong.
Cheers
Click to expand...
 
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ivan H

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I just started putting one together. I have the trimpot etc & all that half of the board done, with the SCR, diodes & resistors in place.
PM me & include ur email & I'll send u pics etc, as I cant put pix up here (tho if u wanna put them up after I send to u it'll be fine). Basicly the same layout, just the 16 ohm is replaced with an 18 ohm & the 220 & 120 ohm & their jumpers are removed. The trimpot is where the 120's jumpers were with 1 end pin & the middle "variable" pin going to ground on the foil strip down the edge of the board, & the other pin on the small foil pad. Also on the small foil pad is the 51 ohm that is laid out in the same position that the 120 ohm was.
I'm also using a 3.3uf tantalum timing cap instead of the normal 4.7uf (to allow 10,000 + rpm on motors with port timing suitably modified). I will also use one each of 0.47uf, 0.33uf, 0.22uf & 0.1uf tantalums on jumpers (if I can physically fit them all in), to allow much finer tuning of the hi rpm retard curve.
So when its completed it would be good to get pics of up here. Cheres
.wee.
 
KCvale

KCvale

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Feb 28, 2010
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ivan H said:
I just started putting one together. I have the trimpot etc & all that half of the board done, with the SCR, diodes & resistors in place.

Basically the same layout, just....
jumpers are removed.
The trimpot is where the 120's jumpers were.
I'm also using a 3.3uf tantalum timing..
etc. etc etc.
Click to expand...
Ivan, I just downloaded this spiffy free Windows PCB design program called Express PCB that has DigiKey part numbers.
http://www.expresspcb.com/index.htm

I have used DigiKey a lot in the past and they carry most anything you could ever want want but not a at great price, the thing is other vendors will let you order with DigiKey part numbers ;-}
http://www.digikey.com/

E me over your newest pics and component list preferably with the DigiKey part numbers.

By the pics I've seen I should be able to design the PCB to drop into one of these little plastic boxes.
http://www.mouser.com/ProductDetail...=sGAEpiMZZMsrGrAVj6eTvV2qliFzow05rvukx2CRC6U=



That is the box I use to cap off the CDI when I rewire the ignition system anyway so without the coil it should easily to fit in the CDI component board and maybe even the keylock switch I have used before and I have a bunch of those boxes, I buy them 50 at a time as every 2-stroke gets rewired so this may really be a cool option I can offer my customers.

For that matter it is not much more work to knock out 10 a shot than just one once you have photo-etching a schematic template, especially one with multiple boards you can etch in a single pass and then cut out ;-}
 
KCvale

KCvale

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Waiting on parts and my help wanted a day off so I looked into making a photo etch template and this is how it works compared to a hobby bread board template board.

This is a nice example of a pre-etched PCB breadboard match.



Everything diagrammed below is just example of how the program works, not a circuit!

With photo etching a copper single sided PCB all the copper is yours to remove as you please.

This little program I just tried lets you set a PCB size, then select components for a list and put them wherever you want by size and proximity like this



That is the top view (not copper side) with representations of the actual component size and the connection points.
I set my board size to the size of that little plastic box above with similar components to this CDI like a big cap, SCR, resistors, diodes and caps.

Then you change to bottom (copper side) view and make your connections any way you like.
What you want to keep in mind here is you want to dissolve away as little copper as possible especially on the + and - planes.



When it's all said and done you have a shareable printable photo etching template like this partial fictitious one.



That is a horrible example of well designed PCB as only the green would be copper but you get the point, it's pretty easy do it yourself.
 
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ivan H

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Hi KCVale, yes Digikey cetainly do have an incredibly large inventory, usually with a huge variety of each component. Absolutely everything electronics.
Sky120 posted the Digikey links to the C106D1G SCR & a 275VAC X2 rated 1uf film/foil Polypropylene charge cap in post #41. Perhaps he could assist with the Digikey Cat No.s for the other components for the stock CDI. It would make things easier as digikey have such a large component listing my crappy phone runs out of memory searching the cataloge, but I'll get the part No.s for the extra parts ok.
That is a neat program & its a great idea. Breadboards & vero boards get the job done in a pinch but are far from ideal, plus they really increace the chance of error when someone isnt really familliar with electronics projects. Ur idea will practicly elliminate that problem. Great idea.
I use the little project plastic boxes by cutting the corners of the board to allow the board to clear the screw bosses inside the box. I'll measure 1 up tonight & get back to. Thanks heaps for ur assistance. Cheers
 
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SKY120

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Aug 31, 2013
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Here are the digikey part numbers for the parts I ordered:

P16BBCT-ND
CF12JT220RCT-ND
CF12JT120RCT-ND
CF12JT33R0CT-ND
CF12JT390RCT-ND
1.0KH-ND
CF12JT750RCT-ND
CF12JT10R0CT-ND
478-4178-ND
478-4179-ND
C106D1GOS-ND
1N4007DICT-ND
P14785-ND
A26228-ND
XG8T-0231-ND

Hope that helps!

Darren
 
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ivan H

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Thanks heaps Sky120, that helps immensely. Thats the complete parts list including jumper pins & jumper shunts & all, right. Yes, that is a big help.
Let us know how u get on with ur CDI when u get ur CR80 coil ok. Cheers
 
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ivan H

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Hi KCVale, the Digikey Part No. for the 0.5 Watt 200 ohm 25 turn trimpot (or "cermet") is T93YA-200-ND. The other 2 components needed for the trimpot conversion are a 51 ohm & an 18 ohm 0.5 Watt metal film resistor (which I didnt get a part No. for).
The plastic project boxes I use measure about 83mm x 53mm x 30mm on the outside.
Using the multi turn trimpot to set initial timing, u would need to start by making adjustments with around 4 or 5 full turns to get it in the ballpark, then start fine tuning using smaller adjustments to get it spot on. Could take quite a bit of testing in the low rpm range while going uphill, but thats the nature of fine tuning for best performance, isnt it. Cheers
dnut
 
KCvale

KCvale

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Feb 28, 2010
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ivan H said:
Hi KCVale, the Digikey Part No. for the 0.5 Watt 200 ohm 25 turn trimpot (or "cermet") is T93YA-200-ND. The other 2 components needed for the trimpot conversion are a 51 ohm & an 18 ohm 0.5 Watt metal film resistor (which I didnt get a part No. for).
Click to expand...
Well, there are more parts in list than on the board so help me out here.



I have it all in a 2003 Excel spreadsheet here.
http://KCsBikes.com/CDIpart.xls

Note I can't buy less than 1000 of those *51Ω resistors from DigiKey but with the new design trim pot and 5% tolerance is there not something more common that can be used?

Ivan, just do another schematic diagram with the final parts with values and E-mail it over to me as I just don't have time to wade through 8 pages of text changes in this topic and try to follow what keeps changing.

For example there is only 1 diode in the parts list if memory serves there is 5 and some were suppose to be Zeners?

The plastic project boxes I use measure about 83mm x 53mm x 30mm on the outside.
Click to expand...
That's the beauty of using a Schematic/ PCB CAD program, I don't have to think in just 2 dimensions, for example all of the resisters and diodes will be mounted standing up so the board simply doesn't need to be that big.
 
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ivan H

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Hi KCVale, yes, good catch on the excessive parts count.
If one wants to use a trimpot, there are 3 parts that are substituted plus another 2 parts removed (being a resistor & its jumper/pins).
The parts substituted are;
the 16 ohm changed to 18 ohms;
the 120 ohm & its jumper pins changed to a 51 ohm & the 200 ohm trimpot. Obviously the 51 ohm goes where the 120 ohm was & the trimpot goes where the jumper pins were:
The 220 ohm & its jumper pins are removed.
The actual board (copper foil pads) stays exactly the same for either variant.
I will look up the part No. for a single turn 200 ohm trimpot as well so people that wish to build a "variable" type have a choice of single or 25 turn trimpots.
A schematic will come as soon as I finish putting together, which should have been last night except I got caught up in the friday night yahoo thing. Ur right about standing resistors & diodes etc on there end greatly shrinking the physical board size. I do the same when making electric guitar effects pedals (stomp boxes) where maiking the board as small as possible is a priority so as to fit a couple of jack sockets, 2 or 3 potentiometers, a 3PDT footswitch, a 9V battery & the (insulated) board along wire all connecting wires inside a small die cast alloy box. Before the advent of SMT (surface mount technology), mounting components in this way to reduce board size was common practise. Does make drawing (pen & paper) a layout kinda challenging tho. Cheers
 
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SKY120

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well got the cr80 coil today and nothing... frustrated... I have gone over the circuit so many times I swear everything is correct.

Ivan, everything in my parts list looks ok right?

One thing I noticed tonight, broke out the ohm meter to check and I get continuity between the coil lead and the engine case. I'm open to any suggestions now!!

Darren
 
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