Bigboat

[link=http://www.5bears.com/tim4.htm]TIM 4 schematic[/link]

Bigboat

The art to perfection

Use for the hs-bridge not normal diodes like 1N4xxx, but take Schottkydiodes - the 1N4xxx are to slow.
Lower the capacistor (and/or resistor) in the ocsillator to 3uF3 (and/or 390 Ohm) to load the inigtion capacistor faster, a higher (~20.000) rpm is now possible.
Use shielded wires for all external connections (hallsensor/power/bobine), high frequentie pulses disturb the CDI.
Make a metal shield to protect the timer/PIC for interferes pulses from the powerboard.
Lower the pull-up resistors to <4k7 Ohm to eliminate interferes from the outside, like the spark and lightcoil.
Mounth the PIC direct to the PCB and don't use a mounthingfeed, with vibrations the PIC will lose contact with the PCB.

Changes:
PickupLED moved from RB7 to RB4 and rewrite asm-file.
No leads for incircuitprogramming on the PCB, I use a 18 pins clamp to program the PIC.
You need pin 12, 13, 14, 5, 7 to program with [link=http://www.ubasics.com/adam/pic/icp84.html]this programmer[/link]
New PCB is ready to use a 4 MHz resonator or x-tal with capacitors.

On [link=http://www.modelbouw.gompy.net/cdi/cdi.htm]my site[/link] you can find a new PCB for incircuit programming.
Also new asm and hex-flies named Zenoah2a.asm and Zenoah2a.hex

lumpylumpy

Hi,does anyone know how to increase the power of the inverter?more turns in the secondary
=more tension,what about power?i am using an E core tranformer.And i whant to use a 1uF capacitor instead of the 0,47uF capacitor;then the max. freq. will be half right?what can i do to increase the freq. of the inverter?thank's!

c_moore

Hi LumpyLumpy,

I use a 1uf cap on my design and I use less windings on the secondary and get more voltage. I get around 400 volts.I do this by increasing the inverter freq. I can pm you or email you a schmatic.

Bigboat

Hi Charlie,

If you increas the inverterfrequentie, your max rpm will be less.
With the *normal* values, the max rpm is ~140 Hz (=60x140=8400rpm)
If you speedup the iverterfreq of the coil to ~180Hz, the max rpm will be 60x180= 10.800 rpm.
BUT......if you speedup the inverterferq of the coil, you get less current to load the capacitor for the spark.
Now you need more voltage to evaluate the current you lose.
I hope you understand wat I mean to explain.....In Dutch it's muts easyer to explain this ;o)

BTW(1), I get my mail to you back....5.1.0 - Unknown address
BTW(2), You can send me mail now, rr.com don't block the mail anymore.(I hope)

CU, Rob / gompy.net

c_moore

Hi Rob,

I don't understand why a higher Inverter freq. will lower the RPM.It seems that the HV Cap. will charged with a higher freq.Other factors must be involved.

Bigboat

Hi Charlie, you're right......in Dutch it's easyer to explain for me.....sorry for the mistake(s) I make.
I mixup *in* and *de*, *in*creas = speedup and *de*creas =slowdown....yes ?

If the freq is speedup the coilfreq, the capacitor have a better load.
If the freq is higher, the bridge can make a better/equal DC to load the capacitor.
But you need time to load the capacitor.
If the capacitor is to big, the capacitor will not load complete between two sparks.
Only a complete loaded capacitor is given a good spark.

Maybe I must go back to school to freshup my english [8D]

c_moore

Hi Rob,

Your English is Fine.I think you do Pretty Good.Maybe its me that needs to learn to speak Dutch? . I agree if the cap is too big then it will cause trouble.

jmj

Bigboat, you have done great work on the CDI. What is the current status of your work?
Have you actually run the CDI on a real engine, and if so - how did it do?
What about the curve - did you have to make it reversed?

I am sorry for not having contributed to the project lately - i got a bit tired of it and put it aside for a while.
I still have not run my Stihl 41cc, i have to make a mount for the carburettor, and for the pickup.
I will try to do some work on this in the next weeks.


Regards,
Jon-Magne

Bigboat

Hi Jon-Magne,

I don't have test the cdi on a real engine, but on a real enginetester.
The cdi works great.....if you reverse the timetable, like I did.
I have to speedup the freq of the coil, 140 Hz was to slow to run high rpm.(~140 Hz =60x140=8400rpm)
I dubble the freq so the engine can run now ~17,000 rpm........I like 20,000 rpm, need more to test.
BUT.....the coil/ocsillator will not work with this freq.
I'll try to replace the coil to a real transformer 2x 3Volt - 220 Volt with a flipflop.
Something like this but NOT with this the components !!

lumpylumpy

hi CharlieM,i would interesed in your schematic,have runed the inverter whit another cdi on suzuki 50cc scooter and runs fine,but the spark is not so big.....for me!With an 1uF capacitor on the cdi doesnt doo max. revs. only about 7000 rpm, and i need 12000rpm!some sugestions? I used the original inverter schematic with fast recovery diodes ,E-core transformer and only half wave rectified and i got out about 120 voltsfrom the inverter.

c_moore

HI Lumpylimpy,

You could try to lower the resister value at the RC(Resistor/Capacitor) circuit.

Bigboat

We gone do some calculation to understand the powerboard,

To get a big/strong spark, we need Joules.....a lott of Joules, mega Joules.
For a good spark and a high rpm we need about 90 mJ. (45 mJ for ~8000 rpm)
This Joules we get from the capacitor and the high voltage coil on the powerboard.
If we have 300 Volt from the coil and the capacitor is 1 uf, we have (0,5*C*(U*U)) = (0,5*1*(300*300)) = 45 mJ
With this calculation you can see we don't have enough Joules.
Wat can we do about this.....
Increas the capacitor, but you get a longer load time....not good !
Increas the voltage, easy to do......more windings.
If we have 600 Volt from the coil, we get (0,5*1*(600*600)) = 180 mJ, we need only 90 mJ !
Now we can decreas the capacitor to 0.5 mF, this will also decreas the laodtime from the capacitor to 1/2 of the normal loadtime.
If the laodtime from the capacitor will be shorter, the rpm will be increas.
We need also some current with this voltage.
A easy way to do this is to wind prim two windings (to gether) on the coil (2x 20 windings of 0.5mm).
The sec-winding must be increas to ~1200 of 0.1mm to get ~600 Volt.
BTW, don't forget to make the resistor of the ocsilator smaller ~1/2 of the normal value for a higher rpm.

Bigboat

Raedy for ROCK AND ROLL [8D]
On the first pic I have make a flywheel like a degreewheel.
On the second pic you can see, the pickup is movable to adjust the CDI on time.





Now we gone test the the CDI in realtime [>:]

c_moore

HI Rob,

Thats a good job you did. how did you transfer the degrees to the flywheel? Regards Charlie

captinjohn

Bigboat: The photo of the adjustable pick-up....is that the prop end of the crankshaft? Also is that a poulan engine? Thanks Capt,n P.S. Very nice work!!

Bigboat

Hi Charlie

I print the degreewheel on sheet and glue it to the flywheel.
[link=http://www.tavia.com/free_degree_wheel.html]Free degreewheel[/link]

Bigboat

It is not importante where the pickup is placed.
You only need to know the turning direction, left / right.
Place the pickup ~35 degrees befor Upper Death Point.
The engine is a Stihll (?) 43ccm.
I'll place some new pics with a better look to the pickup.

Terbough Bob

My Feedback: (10)

This is weird... I thought I was on RCU, but when I clicked on this thread, I found myself on the Megasquirt site. Can I perhaps inspire one of you to research the possibility of programmable fuel injection?

http://www.msefi.com

Bigboat

I have test today the CDI and find some problems.
Sometimes I missing a spark, sometimes a spark at the wrong time or to muts sparks at the same time.
It seems to me a EMC-problem in the pcb I use, the pic making (or not) his own sparks.
Also the energy for the capacitor is to small when the engine runs high rpm.
If I calculate the power I need (5 Watt), the capacitor must be ~4,7uF instead of 1uF.
Inside the cylinder the pressure is ~12bar on 4000 rpm, with this pressure there isn't a spark anymore.
Back to the drawingbord [&o]

c_moore

Hi Rob,

I have expirenced the same problems in the past and the way I solved it was to decrease the secondary windings and increase the primary windings and then speed up the oscilator.Also that is what led me touse the oscilator configuration I use. It works great up to about 20000 rpm. regards Charlie

Bigboat

Hi Charlie......wat oscilator config you mean....the schematic you send to me with the IC IR2153 ?
I make the same changes, change winds and oscilator frequenty, but still this problem.

c_moore

Hi Rob,

The Config. with the RC circuit having the resistor goto ground and the cap going to the positive rail,and then the feedback winding going between the resistor and the cap.I also Use a 100ohm resistor between the base of the transistor and the feedback winding as well.For some reason I got the best performance from that set up. I can try to Email you a copy of the schmatic I use if you want. Regards Charlie

TooLy

Question about magneto ignition,
I understand that there is a source coil and ignition coil with capacitor, what makes the capacitor to discharge ?

Thanks.

Bigboat

The thyristor makes a shortcircuit wih the ignitioncoil and will discharge the capacitor.