jpanhalt

Thank you, Bigboat for the lead on transformers.

Last week, I made a trip to a local surplus store and picked up an assortment of ferrite toroid cores. The first one I tested was 17mm O.D. X 10mm I.D. X 6.7mm high. I used 32AWG for the secondary (400 turns) and feedback, and 25AWG for the primary. It was just for a test and the limit on turns was because the shuttle I made for winding was too big for the hole as the windings increased. The circuit was modified to use an NPN transistor and I used a voltage doubler for the output. So far, it seems to work as good or better than an import ignition from China. By "better" I mean the spark intensity and stability seems better at the highest test RPM (about 18,000 rpm). Maximum peak current during charge is about 900 mA, as estimated with an oscilloscope and small rsistor.

I plan to do more characterization and comparison of it today with the Chinese ignition. It was just plain fun to see it work so well and be so simple.

As I read more on ferrite cores, it seems the choices are almost limitless, and the characterizations and color coding schemes are completely unstandardized. I would like to be able to describe what I do, so it can be reproduced. Not everyone can visit the same surplus store in Cleveland that I went to. So, the core I chose to use in my initial test was the only one with an identifier number on it. That number is: 2D10-55115-A2-2. I have searched Google and cannot find any technical data on it. PartMiner lists that number, but has no other information. It is grey and has a smooth epoxy-like coating. Does anyone have any idea what its characteristics and/or manufacturer is?

John

Bigboat

I test every ferrit I can get.
Some ferrits lookslike the same, size and collor, but they are all differend.
It's allmost impossible to say *you need this ferrit*.
I can only say, go to the store and ask high frequenty ferrits and don't use ferrits within powerleads.
The ferrit must handle at last 1 kHz for the ocsilator if you whant 30.000 rpm.

captinjohn

Here is something interesting! http://perower.tripod.com:80/i.html Give it a try Capt,n

captinjohn

More...electronic gagets http://www.electronicsinfoline.com/C...ects/1515.html Capt,n

venomxx

Any of you guys got a fully functional one yet ?

venomxx

I am new to this forum and this post really strike my interest.

I'm also a horrible at soldering. The last time I tried to build a circuit board, I made a bunch of cold joints and the project went down the drain.

I really want to make a CDI for my weedeater engine which i will use on my r/c boat. It would be very nice if I could get the help from you guys (those who have already made, and are in the making of this CDI unit).

Starting from scratch and hope to build my confidence in building circuits.
Any recommendations and how I should approach this ?

Part lists ?
digikeys parts ?

Where do I get Hall sensor ?

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venomxx

Hi everyone,
I went and etched the copperboard today.
They came out looking pretty good.
One of the etch board is the Pic programming.

Hopefully I can get that to work this weekend.
Just done cleaning up

Bigboat

Beware, you gone build the *old* cdi and can't use the files from the *new cdi* !!

venomxx

uh oh... which file is the new cdi? i got that from the filke named "Component layout big PCB"

Bigboat

http://www.modelbouw.gompy.net/newcdi/newcdi.htm

http://home.online.no/~jon-mj/cdi_ignition.htm

venomxx

okay, but I have a question. Did the old CDI work ?
I noticed you said that the new CDI is in testing mode and not fully functional.
I dont mind building the old one if it works Then Ill build the new one when its fully functional. Since I dont have any equipments to help you guys testing it, I wouldn't wanna do that!.

venomxx

... where is everyone this weekend ? Out fishing ?
ive been tinklering all day trying to find some spare electronic parts from the old radio/anything with a pcb board. I could only find a few usable parts. The rest looks like have to be order from www.digikey.com
Their Hall sensor is on back order so imma have to wait for next week for shipment.

I etched the wrong PCB...the old CDI. So i gotta make a new board. Probably next week though when everything comes in I can just put it together and cross my fingers hoping I didnt do anything wrong.

Whats this Excel sheet that I hear everyone talking about?

jpanhalt

Venomxx,

If you have not already ordered, mouser.com is an alternative source and has no minimum order. DigiKey is usually my first choice for most components -- mainly because of fast shipping and almost overnight transport to Cleveland for regular ground rates; however, Mouser seems to have a better selection of some items, such as infrared detectors. It might be worth checking with Mouser, next time. John

venomxx

John, I placed the order last night. I wish I got your message a little sooner. Digikey didnt' have the BD242 Transistor in stock either. I'm hoping I can pull that out of a power supply somewhere ?

Do you or anyone know whats a replacement for it ?

jpanhalt

The BD242 characteristics are not particularly critical in that circuit. It is a PNP, medium-power transistor. You should look for alternatives that have similar voltage and current ratings in the TO-220 case with the same pin assignment,i.e., BCE from left to right looking at the "front". There are lots of possibilities. The requirements for the case and pin assignment are because you have already made or plan to make the same PCB pattern developed by BigBoat and JMJ. The other characteristic to look at is the Hfe, which essentially is the amplification factor. Most circuits are not particularly sensitive to that factor. The BD242 Hfs is 25 at 1 A and 10 at 3 A. A close match to those characterisitcs is the TIP32 (45V rating) or TIP 32A (60V rating). DigiKey (and probably the other vendors) allow a part lookup by characteristics from its web page. There were 9 pages of similar parts (i.e., same or greater voltage and current ratings in the TO220 or similar package) in the DigiKey catalog. The TIP32/32A was just the first one of that long list that was listed. Try Radio Shack. Although their selection is very limited, many of the parts it carries are common generic substitutes. It has a TIP42, which is similar, but not as close a match as the TIP32. You might try it just to see.

Many radio stores have a catalog that contains recommendations for substitute parts. I believe BigBoat has also given alternative part numbers that can be used.

The biggest problem with using a substitute part is when the circuit doesn't work right from the start. It could be the part, or more likely, another problem in the circuit. Unless you have trouble-shooting equipment (multimeter and inexpensive oscilloscope), it can be hard to find the problem. Good luck. John

venomxx

Okay,
Today I spoke with one of Digikey's sales rep. and they got me the same part you recommended.
So the package should come sometimes before the weekends. I'm shooting for a completion of a CDI unit this coming weekend.

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Bigboat mentioned that every engine is different, so what do I have to do to change it to the right configuration on the excel sheet for a McCulloch engine? ...
Just mess around with it til I get it right ?

eeeek

Bigboat

Normaly a *weedeather* have ~ 32 till 36 degrease ignition BTDC.
Program a straight curve of 34 degrease BTDC.
Your engine have now a easystart of 5 degrease BTDC untill 1,800 rpm.
Above 1,800 rpm the curve will be 34 degrease untill max rpm.
If the engine will run on your cdi, you can experiment with some other curves.
Two stroke enigines will be run better at high rpm with some more degrease BTDC.....like 38 degrease.
Start the advange curve at 30 degrease at 1,800 rpm and end at high rpm (7,000) with 38 degrease.

venomxx

Thanks for all the replies...

As for the transformer/coil. I could wound a 500+rev. on a round ferrite core but that would take an insane amount of hair pulling. Since I read somewhere on one of the posts that others have use normal coils. And the most recent one was from a 12vlt strobe light adapter.
Wella, I happen to have a few right infront of me. I pulled them out from discarded scanners. I used them as light source and they look very bright at night. Not too great for trying to read a book but will shine great.

This adapter would work with my CDI since I wont need it to go higher than 18000 RPM.

I hope I am right ?

venomxx

While waiting for the parts from digikey to come... I figure i would jump start on the project.

I made a coil today using the info on the homemade coil site. But I dont quite understand this :
" Use some coax as cable to the plug.
Make 2 short pieces of wire, one red and one black.
Solder toghether the screen of the coax, the black wire, and both start ends of the windings.
Solder the core of the coax to the end of the thin winding.
Solder the end of the thick winding to the red wire. "

This is what I understood from reading it:

" use some left over wire as cable to the plug.
Make 2 short pieces of wire, one red and one black.
Solder together the ??????, the black wire, and both ends of the windings *Which windings ? the larger wire or the smaller wire ?
Solder one end of the thick winding to the red wire."


To clarify it more, the coil has a total of 4 wires: 2 from the larger wire coil, and 2 from the smaller wire coil.

Could someone tell me in simplier terms ?

venomxx

The Transformer Coil - Ferrite Ring

Done wounding the ferrite transformer tonight. It took me a good 2 1/2 hours! All the wires packed in nicely, a nuggly fit. I'm wondering if that is going to be a problem ?

The last 20 .5mm coil had to be squeezed in and pushed into the 1st 400+windings. Ugggh...does that spell "TROUBLE?"

I do not have any degree in electronics so ... just hoping for the best? lol

Any advices?

venomxx

jpanhalt

Goodmorning, Vennomxx;

Yes, it can make a difference if the wires are stuffed in too tight. But, the coil is done, so I would go ahead and test it. My test coils have been made on a toroid core that is 0.65" OD X 0.40" ID X 0.25" high (i.e., Magnetics #55115), and I have not had any problems with such tight packing. In fact, the central hole (window) was still more than 0.25" in diameter. I used 32AWG for the secondary and feedback coils and 25AWG for the primary. Please give your core dimensins (inches or mm) and wire gages -- obviously, one can make a conversion for the wire sizes, but when troubleshooting, I want to be sure were are using the same units. BTW, the 55115 core is not ferrite, as I am doing some experiments with powder cores. I would not recommend that you use that specific core material. I mention it only because the size was OK.

Today is probably your DigiKey-day . Good luck. John

venomxx

THanks JpanHalt,
but the order wont come in til Friday. UPS ground is so slow. If I have known their USPS priority mail was cheaper than UPS ground, i'd pick that option instead. lol.
But anywho.


I got a question for ROB aka B i G B O A T.

How do you start your engine with this CDI if it were mounting on a boat ?

Bigboat

There is a pullstarter on the engine, but it can be also with a start-engine.
The cdi is located in a small box behinde the engine, but can be mounth everywhere around the engine.
!!! not into the radiobox !!!

venomxx

I saw on Ebay the other night a modded engine that has a push button start.
The motor is mounted right on the side of the flywheel. It has some sort of mods with gears. I'm wondering if anyone has done similar mod to their engines?

Push button start sounds like fun since I am using a 6channel radio. Maybe I could try to utilize all the channels for extra functions: rudder raised and lowered, perhaps a closed/open intake to cool engine head since i'm not using water cooling.

While at it I might add rocket launchers and a rottating gattling gun on the hull ~ okay that's just a dream.

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Editted:

COuld someone answer the question I have about which wire to solder on the Ignition coil ?

What about using an HV transformer from a Television for a spark coil ?
Is that even possible ? Those making 10k+ volts