The pic can do anything you like, but this is just a concept drawing.
The ocsilate frequentie must be more then the max-rpm you wish, I think dubbled or trippled.
I've found also problems with the BT151, sometimes the cdi sparks without a puls from the hall.
It's very critical how to build the flybacktransformer, you blow within 1 sec the transistor and the scr.

Question, wat will we do with the old kit ?
There are a lot of people who not only have build this schematic, but also use it.
Do we upgrade the software, if possible, or do we dump this project and gone use the new.
I think the new schematic is much better, no flybacktranformer and no burnout transistor and scr anymore.
This was as I know the largest bottleneck from all the CDI-builders.
I invite the programmer to this group to give him direct information from all of you.

Rob, do you have a new board design to go with the schematic?


John

Not jet, it's possible the schematic will change a littlebit.
It's all concept, the programmer is the one who decides the end product.
The pinnumbers are random and for the transformer I've to look how small it can be.
With the values in the schematic the Voltage will be ~250VAC, I think it must be 400VAC.

Of Coarse it is nice to have the old on file for people to use and try if they wish

call the next board Mark 2 (Mk2)or something

But differently keep all the info of the old one on the site and move forward to the new

upgrade the software as it would need to ,

just my thoughts out loud

cheers
brett

Frankly, I am disappointed that we don’t see more discussion on this thread regarding circuit design and RC airplane applications. This is a RC airplane engine forum. On the other hand most guys I know don’t care about the electronics – they just want it to work.

Rob

1. You introduced a new circuit for consideration. Is this based on Jean Marc Veyrat’s design?

2. If so, he uses a single MOSFET to pulse the transformer. You propose using two MOSFET’s with a C.T. primary. Why? What are the advantages and disadvantages of each concept?

3. You propose using a MOSFET instead of SCR to fire the spark plug. Why? What are the advantages and disadvantages of each concept?

4. You talk about how critical the “flyback� (sic) transformer is. What makes it critical and how do we avoid problems when winding the transformer?

5. If we start discussing a new circuit design concept should we not open a new thread?

Gr8flyer

In the power board design concept that we are using, I noticed that the transformer coil ratio is 15t to 450t (or something close to that). This is a 1:30 ratio. Am I correct in assuming that capacitor C7 charges to .67 of full B+ voltage or (.67 x 5V) = 3.35 volts?

Thus (3.35V x 30) = 100 Volts.

If so, how are we getting 400+ volts across the secondary? What am I missing here?

Regards

Al

John

I have the board laid out for the CDI I am building (which is a combination of Rob's timer board and your power board). I will finalize the layout as soon as I get the toroid transformer to verify pad location. It fits nicely on a 2" x 2" board. I will post it here as I go along.

I use ExpressPCB software for drawing schematics and laying out my boards. Great stuff and it's FREE!

Al

I don't know where do you get the informatrion this is a airplane engine forum.......this is a engine conversion forum for every engine on every rc-model.


NO, I didn't even know who Jean Marc is.

There are many roads to Rome, this designe can make more power out of the transformer.

A IGBT or FET can manual open or close, a scr needs negative Voltage to closed.
If you can read, there are to many troubles with the scr, so we take a other concept.

Intern resistant of the scr and wat type they use, how is the tranformer made and wat material they use, aso.

NO.

Do you know how a sparkcoil funtioning.....this is also how we get 400 Volt from a flybacktransformer.

Rob,

You might want to rethink using a 12F675 pic for the new design. For one I don't think the pic has enough rom for the program it going to take to make this work and second I don't think it will be able to control timing and provide the output for the transformer. I think a 18F pic is more suited to the job. I had help to take the timing code and fit into a 12F pic and I had to strip a lot out of it. If you want this thing to be able to output real time data thats more coding.Also the max clock speed a 12F pic can run at is 8 mhz. You might need something more close to 20 mhz and a lot mor program space.


Al

the transformer oscillates or turns off and on very fast. This is how the voltage is stepped up to go from 5 volts to 400.

Rob,

Another question is are the guys that are writing this code using MikroC or another high level language compiler? I know you have to do one thing at a time,but if they write in asm then that will make it hard for someone to use if they have to use MPLAB to compile it.

Hi Charlie .....isnt asm easyer to muck around with even tho you have to compile it ?

im a newbie to this but when someone was helping me with pic control racing lights it was easyer for them to tell me what to change etc

brett

Hi Brett,

I guess if someone teaches you asm then is might be easy. For Me and I think the majority of the people here wanting to make a CDI unit and the timing board with little or no programming skills then a high level language is the way to go.I have been messing around with pics for 5 years and all I have ever used is a high level language. It saves a lot of time.I don't know if you ever used MPLAB,but for me it is a real pain in the ass. I guess if I sat down and spent a month learning it is would be ok. And thats the thing, I think people want something that is easy to use.Not something that takes a month to learn. This is just my opinion.

What is hi level mean?

and like you say i do not want to know how to program just built this project and run it,

yes i have used MPLAB before and maybe i was lucky it only took me a month to compile the racing light program i used for our start lights in our pocket bike club and made it remote
control so the race starter could just push a button to start the race,

i agree with you if it is easyer for sure

brett

Hi Brett,

A high level language is something like Mikro C or Pic Basic. A low level language is asm. Asm is one step up from machine language (Hex). The draw back from a high level language is each instruction takes several asm instructions which makes not as efficient as asm. So if it's done iin asm it is more efficient and runs faster,but is harder to understand for someone that has never programmed before.

Sorry Charlie, I make a mistake with the levels.....not with MicroC [8D]

Low level program is machine language, asm, visual basic (C), Pascal, Jal, Picbasic are high level program languages.
MicroC is just a compiler, a translator to hex, nothing more.

Al, the toroid I use is very efficient..Take a look at the link I provided a few posts back for the info..
The physical size of the toroid we are using comes to about .750 inch diameter. The lead spacing is in a setup of 2 wires each at 3 equally spaced spots on the diameter around the core windings.
One of the existing board designs has hole locations that my toroids fit within. Never had a problem substitutuing the toroids for an ecore wound transformer.
The design of the windings relies on the transistor with it's feedback winding for a bias. As this bias is applied, it increases the current flow though the primary winding creating a voltage and current gain, along with the resistance/capacitance oscillation circuit, we have the gain applied from the transistor. Depending on the individual transistor, gain will be multiplied by your values you came up with.
The resulting voltage stepup from the toroid will charge the cap to all but it's full rated voltage. I have tried 250 volt caps and only got half the spark.
Everything works well together it seems, so I left things as they were for years.. Feel free to experiment!

John

Thats not true Rob. http://www.computerhope.com/jargon/h/highll.htm

Rob,

You can't change your reply....

You know wat I gone write.....SH [:@]
Thats the problem to translate, sometimes you write thing wat are meaning just the other way wat we mean.
And I read to fast and don't think twice

i want to speak another language so when i make a mistake i can get away with it also haha..... classic



Charlie thanks.....what about those new chips ..... i forget the name but they are easy as to use and come with software to use

not picaxe ...... theres some guys on youtube showing you how easy there are to use and there are different models,

i just cant think what they are call right now

brett

I only get 2 years english on school in 1970, the rest I've learn myself from internet, tv and manuals.
Increase sounds for me in my language make it smaller, but you mean make it bigger.
And just wat I write, i'm to fast with reading an awnser it.......sometimes I dont think.

You mean basicstamp ?

im teasing you, and testing your English humor....

No not Basicstamp..... in the youtube videos they look cool

I don't have, I'm dyslexic

And the name will be.............chip(munk)

Brett,

Post a link to the video. The only ones I know of are Picaxe,BS2(basic stamp). Those chips use a interpreter the code in not really compiled.. They are ok for beginners ,but wont handle the timing critical stuff like we want.

Ok i found it .....

there are lots of different boards depends on how much you want to do etc



http://www.youtube.com/profile?user=...58/pMV2isNm8JU

brett