Programmable Open Source CD Ignition PIC1840 - Page 4 - RC Groups
View Poll Results: Whatís the most important thing to you?
Lowest possible cost 3 23.08%
Make it as small and light as possible 6 46.15%
Battery longevity is very important 3 23.08%
Highest power possible 3 23.08%
Highest RPM possible 2 15.38%
Only use through hole construction 2 15.38%
No winding of transformers 4 30.77%
Group buy of components including boards 0 0%
Group buy of boards only 1 7.69%
Iíd rather buy a kit with everything in it 0 0%
I want to buy a pre-built & pre-programmed system 0 0%
I only want to use a 4.8v Ni-MH battery 2 15.38%
I only want to use a 2S battery 1 7.69%
I only want to use a 3S battery 1 7.69%
I want to use a 4.8v battery to 3S battery 5 38.46%
I want to use only off the shelf parts from Digi-Key or Mouser 3 23.08%
I want the Timer board to be separate from the HV board 6 46.15%
I want a combination Timer & HV board 1 7.69%
I want all the options possible using jumpers 3 23.08%
I want a USB connection 2 15.38%
I want a serial connection (DB9) and Iíll use my own USB adapter 3 23.08%
I want a ICSP connection 3 23.08%
I want a premade parts list (BOM) at Digi-Key 2 15.38%
I want a premade project parts list (BOM) at Mouser 1 7.69%
I want 1 design and 1 design only 1 7.69%
I want optional designs to choose from and Ill make the boards myself 8 61.54%
Multiple Choice Poll. Voters: 13. You may not vote on this poll

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Dec 11, 2012, 07:19 PM
Registered User
I only have about 25 transformers left from my last supply order. In order to get more, I must buy 100. If the demand is high enough, I might reorder. Same with the ignition coils, 100 at a time. Otherwise, we need a new source for them.
I'll post a picture if it works, of what I have here.

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Dec 11, 2012, 08:40 PM
Registered User
Trying a picture post. May not work from my phone
Last edited by gr8flyer55; Dec 11, 2012 at 08:44 PM. Reason: Added picture
Dec 11, 2012, 08:48 PM
Registered User
E-core transformer I use.
Dec 11, 2012, 09:03 PM
Registered User
Early version of ignition board.

Last edited by gr8flyer55; Dec 11, 2012 at 09:13 PM.
Dec 11, 2012, 09:15 PM
Registered User
No comment on last picture except it also makes sparks.

Dec 12, 2012, 02:25 AM
supreme being of leisure
ZAGNUT's Avatar
i like the toroids. they may not be viable for a commercial product but as long as i have to wind my own anyways i may as well spend a little extra time for a superior transformer.

there is an infinite selection of prewound E-core transformers that "should" work but i haven't had any real luck with them. it seems like the ones that do work are always too big for what i want. the pot cores with the screw holding them together are supposed to be better than E-cores but other than a couple of oddballs in my collection i haven't found a good source so i haven't played with them.
Dec 12, 2012, 10:11 AM
Registered User
That is true Zagnut. They are tedious to wind, but if done correctly without crossing turns or getting kinks in the wire, they perform well. My procedure for winding the 400 turns is to use a shuttle to wind the wire onto before starting the winding process. Using a piece of 1/8" wooden dowel of 12" length, I cut a V notch in each end. This holds the wire onto the shuttle. For a 1/2" diameter toroid core, it takes about 26 feet of #34 AWG enameled magnet wire to get the 400 turns on the core. I tape one end of the wire onto the core exterior leaving about 1" of wire free as the start lead. Passing the shuttle thru the center of the core for each turn, winding carefully to give an even layer without crossing adjacent turns over each other. The mor turns you pass thru it, the smaller the hole becomes. Time consuming for sure, but using this method, I can get the 400 turns completed in less that 30 minutes. The primary and feedback wires require no shuttle and are easily done freehand. Tape each section in place with a strip of tape, keeping them tight and completing the job.
A miss count on the secondary turns of a few winds is usually not too much of a problem. I've had voltages vary though from 250 to 350 between wound cores, so I know first hand about missing turns in the order of 50 or more making a huge difference. Your results may vary. Neatness does count in this case!

Dec 12, 2012, 12:57 PM
supreme being of leisure
ZAGNUT's Avatar
wow, 30 minutes is quick! i might get one done in an hour at best but then i don't have a lot of practice....maybe 10 cores at the most.

i use a short 4" shuttle made from 1/16" plywood, easier for me than the long one. after i load the shuttle i shrink a short piece of shrink tube on one end as a cap to keep the winds in place. to unload a couple of winds i just slip it off and then back on....and by always passing the capped end through the core first i avoid kinks in the wire.

have checked with a couple of shops that have machines to wind the little toroids and after hearing the prices it's no wonder all the manufacturers go with E-cores...
Dec 12, 2012, 01:34 PM
Registered User


I agree they want too much for the simple winding process. I did an inquiry to Torelco in New Jersey. I would have to get a minim of 50 toroids done first of all, and the price of $7 each had me stuttering to give them an answer back. Although the price included varnish dip for insulation and strain relief for the leads, the price was if I sent them my cores! Using theirs, price went up to $10 each! That made my decision for me, I keep winding my own.

I like your idea of capping the shuttle preventing kinks, which can happen in a New York second! Been there had that.
Doing winds on an ecore is simpler. I force a square piece of wood into the bobbin center, chuck the other rounds end in my hand held battery powered variable speed drill, measure out the required length of wire on my feed spool, start the winding feeding back and forth making evenly wound layers till I'm all done. Insulation tape that winding and hand wind the other 2. Works for me in less than 5 minutes I have a completed core, almost perfect and they work. I know there are people that go all out, making hand winding machine with turn counters and everything like tensioning devices etc. , but I keep things simple.

Dec 12, 2012, 04:37 PM
Registered User
My approach to winding the torroid is to do maybe 50 turns at a time and then take a break.

For me it is the problem of cramps setting in while trying to hold the torroid, rotate the shuttle at the end of each pass to stop kinks, keep an eye on where the roll of wire has run to after falling on the floor, all this and more that takes the time.

John, I still do not know how you can keep the windings side by side as you go. It seems ok to begin with but as you know, the outside perimeter is a greater distance than the inner, resulting either in gaps in the outer or cross-over on the inner, compounding itself the more the wind progresses.

Having said that, mine all seem to work ok so not too critical. Only ever had one fail.
Dec 12, 2012, 06:37 PM
Registered User
Jeff, I've seen your work and it looked as good as mine. Hey, as long as you get good results from your efforts. As I wind on more layers and the center fills in, you have to do a kind of helical skew to keep from overlapping turns. Results look sort of like a pinwheel winding which to me seemed more efficient. The magnetic flux evenly spread around the core is what makes a good toroid.
If you look at a machine wound core with multiple layers of fine wire, you'll see the pattern the machine develops. Sort of a lead-lag eliptical winding. I'll never get one that nice but I try.

Dec 13, 2012, 03:05 AM
supreme being of leisure
ZAGNUT's Avatar
first layer is easy as you just keep the windings tight on the inner diameter and evenly spaced on the outer diameter....after that, as John says just do a helical wind with increased gaps on the inner diameter to insure no crossed winds. and from what i know a crossed wind really only means that that wind gets cancelled out, not a big issue. i've also seen no difference in winding the primary and feedback evenly around the core or just in a small section with close winds.

biggest issue for me is finding the right core material...i can wind up a pair of cores that look identical but came from different sources (junk box cores) and get very different results when looking at them on the 'scope while playing with component values to get them to work. seems like the ones that do best for me usually run at about 60kHz and way up there the standard diodes aren't going to cut it for rectification.
Dec 13, 2012, 03:16 AM
Registered User
Originally Posted by ZAGNUT
and from what i know a crossed wind really only means that that wind gets cancelled out, not a big issue.
Actually, it makes no difference to the final output whether crossed over or not. Turns are still turns and the ratio remains the same.

What it does is takes up valuable space if you do it continually.
Dec 13, 2012, 03:56 AM
supreme being of leisure
ZAGNUT's Avatar
Originally Posted by bluejets
Actually, it makes no difference to the final output whether crossed over or not. Turns are still turns and the ratio remains the same.

What it does is takes up valuable space if you do it continually.
that's comforting to know.

only real failure i've had other than wrong core material was my ill fated attempt at a shortcut....i bundled 10 strands together, did 40 winds and then made a bunch of connections between the stands to come up with 400 winds.....didn't work AND actually took longer than just doing it the right way.
Dec 13, 2012, 08:59 AM
Registered User
Actually, here is a toroid that Bluejets wound while building one of my combination timer / ignition boards. It looks nicely wound and functioned fine for him.


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