momox

help me please,i want to use the new cdi16f628 for four stroke engine.and when i try to use the map curve cdi16f628,cell is protected and need password to open.

Bigboat

Check your mail

Futterama

How do you find the correct timing for a specific RPM value?

My idea: Load the engine, let it spin a "heavy" wheel or something. Rev it up to e.g. 5000 RPM. Adjust the timing a bit so the engine will run faster = more power. Throttle back down to 5000 RPM and adjust the timing a bit again until you find the timing that gives most RPM with the lowest throttle. Do this for every 500 or 1000 RPM depending on the "timing resolution" you want. I don't know what the practical "timing resolution" would be, you tell me

Is my idea all wrong?

Bigboat

Faster is NOT more force, faster is only faster.
You have to slowdown the *heavywheel* with a brake.
A simple solution, take a wheel from a moped with brake, mount the wheel on the engine (with a cord), start the engine, hit the brake, and now you have the move the timing to see if you get more force.

donaldb

anybody please help me,i want to built this cdi but i cant find the hall effect on my city,can i built this cdi use the pickup coil for sensor input,and where i must change the softare for this modification.thanks

Bigboat

You can use any unipolair hallsensor you can find.

Futterama

How do I see if I get more force? Would the wheel not spin faster if the force is increased?

Bigboat

NOP, you can think about a petrol engine and en gasoline engine.
A gasoline engine have more power and a low rpm.
So faster is not more power, faster is only faster.

captinjohn

I always thought a petrol engine was the same as a gasoline. If different...how??? Capt,n

Bigboat

I don't know how you name *heavy* pertol for big (18 wheels) trucks and *light* petrol for cars.

Kymmy

In english Heavy petrol is Diesel and light petrol is petrol (though in the UK it comes in different grade based on OCTANE RATING..

Anyway enough of that... I've just joined..Currently getting together the parts for the CDI from various sources (mainly ebay and Maplins)... Will UV/etch the board later once I do a slight redesign (going to omit the programming/strobe section).

The CDI is going to fire a 28cc 2stroke weedwacker engine that's been lightened and modified for RC usage (probably going in a 1/4 scale model of a Luton Buzzard mainly as we live in Barton-Le-Clay where the Luton Buzzard and Minors were designed and first built)

I noticed that a few people were asking about pre-programmed PICs? If you;re in the UK I'm willing to program the standard mapping onto them but that does mean that you'll have to do a movable hall sensor to fine tune the BTDC angle..

Anyway lots of pictures to come in the future...

Kymmy

Kymmy

Rob's (BIGBOATS) CDI page has recently vanished from the web... As I'm half way through the project I don't suppose that this page will return?? If not does anyone have the following files on thier PC or know of a mirror site...

CONFIG FILE: testfunc_conf.zip
C-CODE: testfunc_C.zip
EXCELSHEET: 16F628curve.zip

ThanX Kymmy

Futterama

It works fine for me on this address:

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

Kymmy

LOL, typical isn't it...doesn't work for 3 days and then 10 minutes after I posted about it being down it pops back up

ThanX Futterama

Bigboat

At fridaynight one of our servers was burnout.
The biggest problem, the server was just making the backup.
It distroyed also the backup harddisk......**** happend.
We hope everything will be OK now (?)

Kymmy

Rob, nice to see your server back up

Kymmy

Finally found time to work out a board, wind a few coils and grab some components out of my scrap bins...

Got it all together and nope, not working, even the main 470n/400v cap wasn't charging...turns out I made a mistake when i drilled the holes for C7 and this shorted out my BD242, BT151 and TIL151... had replacements BD242 and BT151 but no TIL111 (got a couple of 4N25's coming tomorrow that should be OK.)

Anyway managed to do a few tests, PIC is pulsing OK in test mode (just the fried TIL111 isn't outputing the signal ), on the HT side if I short out the pins 4/5 of the til111 socket I'm getting a nice fat spark across a test plug.

Once I've replaced the opto-isolator I'll do a few runs in test mode, then get a hall sensor and magnet firing the coil... Once all that's OK I'll look at a cleaner board and putting the board and coils in a screened metal box (2x3x0.5 inches) with the output coil internal to the box

Kymmy

Futterama

Kymmy, let's see some good quality pictures of those coils and the test-board :-)

Bigboat

Hi all,

Agian offline, our ISP is broke and disconnect us from internet.
We hope within a few week back online and the server up and running.
At the moment we can only post by a webpage like Yahoo, but we can't receive mail.

Kymmy

[:@] Final coil is OK at slow pulses, but as soon as I put it on the fast test (I think my meter reads about 125hz so about 7k5rpm) it shorts out internally...

As it was my first ever attempt at winding such thin wire at such a high voltage does anyone have any pointers they can give me???

In the mean time at least the main board works so can now work out something a tiny bit smaller so it fits in the box with nough room for the HT in a shielded space at the end..

PilotTiger

My Feedback: (3)

Bigboat, I hope you're going to post the new url when you have one.

Yoram

Bigboat

The URL's will be the same.......if I'm back online.
My last provider can't given me the service I need, so they disconnect me.
Only this time they shutdown the complete line, dsl and internet.
To get a new dsl-line takes a littlebit longer as a telco/telco migration.
I hope within one or two week they repair the line.

lolo396

Hello,

I do my own CDI on the basis of your but with a ATmega8.
He works perfectly with the following coil :
27 turns for primary and 4500 turns 1/10 for secondary.
more than 5 hours with en OS FS120E

To protect the capacitor and the thyristor when the engine is stop, I add a zener diode (200V) between the exit of the rectifier and the ground.


I do a secondary coil for a twin-cylinder :
30 turns for primary and 6500 turns 1/10 for secondary.
I got only one spark (on each cylinder). The oscillator stop and the BD242 is hot.
I think but not sure that the thyristor stay on.
(the same CDI work with the over coil...)

have you an idea to resolve my problem ?

Thanks

Bigboat

The problem is the ocsilator, if you read back we have the same problem.
I don't know if the ocsilator runs to fast or stopped, it's hard to say wat happend.
A solution can be to creat the ocsilatorsignal into the pic.
In schematic we used the ocsilatorsignal is very durty and not reable.
You never know the exact signal the coil / transistor / r / c will make.
It works, but sometimes you can't get enough frequentie to load the C to max.
This means the max rpm is also low and a not a bride spark.

lolo396

I do a PWM 25 kHz to drive a TIP122 and the transformer and I get 200V on the capacitor.

The problem is the same, the Thyristor never shut down. I got only 1 spark. It is the reason why the oscillator stop.
To resolve this, I have to stop the PWM before the spark and run it again 1ms after the spark.
I've got more Volts with this system (130V at 7500 rpm)


Some changes :

PWM : 31 kHz
I use the analog comparator to fix capacitor voltage to 200 V.
I stop the PWM before the spark and run it again 0,5 µs after.

0.03 A when the engine is stop
0.23 A 7500 tr / min (90V)
0.50 A 18000 tr / min (I can't go faster with my test bench)

The transformer I use : primary 16 turns 0.5mm & secondary 150 turns 0.3mm with no air-gap
I've got 150V at 7500 tr/min with a small air-gap but it need 0.6A