CDI ignition and MSnS

baldur · Post by **baldur** » Sat Apr 09, 2005 11:39 am

Yeah this system would ideally be optically isolated from the MS.

ami8break · Post by **ami8break** » Sat Apr 09, 2005 4:18 pm

Hello together,
thank you very much for your feedback and suggestions!

Hello Rick,
@Handmade Transformer:
Cap-dis-ignit.pdf argues why the voltage is regulated/limited to 300V (page 19 last and page 20 1st paragraph, 21 paragraph 'Applications'). For this setup (and for ion sesning!) I'd like to rise up to ~400V. I calculated to reach this with 13 primary turns and 477 (instead of 360) secondary turns. If this is too much I can replace only the 2 primary windings with 14 (372V) or 15 (347V) or 16 (325V) or or 17 (back to 306V) turns and your suggested 10 turns of the driver feedback winding.
When alternator rises up to 14.7V the secondary voltage raises up but less time to stress the capacitor (and other components)?

@Comercial Transformer:
I'll take a look. 5V for feedback would be easy to find at each worn out PC, but 6V...

@Twin CDI:
I made a draft (twin-sparkrite-01.gif) to fire 2 independend coils. I hope I did it right.

@BOM:
Diving into the circuit I found some missing (=???) specifications. Here is a BOM for a single CDI:
R1=47Ohm, 2W
C1=220uF, 16V
C2=47nF
R3=4.7kOhm
R4=10Ohm
D1=1N4002
D2=1N4002
TR1=2N3055 (power transsitor)
TR2=2N3055
RFC=???? Similar to L1=6.5xH=Neosid iron powdered core 17-732-22 (L1)?
W06=??? =4# 1N4936?
R5=470kOhm
R6=100Ohm
R7=68Ohm
R8=3.9kOhm
R9=100Ohm, 2W
R10=10Ohm
C3=1uF, 400V (better >470V?)
C4=15nF
C6=0.22uF, 50V
C7=220uF, 16V
C8=220uF, 16V
Th1=SCR MCR 1076
D3=1N4005
D4=1N4005
Transformer 10/13/13/477 turns
This is just a rough guide. When design is finished (transformer) then I'll ask for capacitor details...

@Trigger:
The Sparkrite circuit was designed for good old points. MSnS triggers like a Hall sensor - do you think there are any modifications required (for reliable triggering)?
I've no idea how to include the SC Hall trigger circuit into Sparkrite.

Hello Baldur,
@Multi Channel CDI:
I'm not convinced that the number of sparks are the same.
»In a wasted spark system the wasted spark (1st) *wastes* some enrgy befor the working spark (2nd) *needs* energy.
»In a dizzy setup there is (enough) time between sparks, but at my flat twin with "twin" MSnS both single coils fire at nearly the same time.

@PC power supply:
I'll try it, but I'm afraid that this is not so easy for me because there are a lot of components around. I hope to find the true pins with a DMM (3.3V, 5V, 12V)

aerowerks wrote:Proper decoupling capacitors and chokes on the inputs and power lines will be necessary to eliminate any feedback into MS'n'S

This sounds far out of my capabilities --> the handmade transformer seems easier to realize. Or is it necessary to protect MS too?
Maybe it would work if the BOSCH ignition module is switched in the line and the 'tachometer' pin signal to Sparkrite CDI (but I don't know if/which delay).

Hello Luke,
@noisey oscilating

slow_hemi6 wrote:it is very noisey oscilating nicely to give off rf

I'm sorry but what says "to give off rf"?
I read the Cap-dis-ignit.pdf aricle again and again. Aren't those Mosfet drivers the reason for 2 sparks at each ignition event? This might be useful for bad chamber conditions (wet, lean...) but ion sensing requires only one hot short spark per ignition event to begin early with ion current data collecting.
Or does the Sparkrite also firs twice (because of »two« power transitors 2N3055). If yes please can you tell me exactly where the interfaces between those circuits are?
Thanks
»Horst

baldur · Post by **baldur** » Sat Apr 09, 2005 4:47 pm

Oh well, I didn't take into account that we would be firing TWO coils at the exact same time, so granted we will be firing more sparks if we are doing coil on plug but still wasting sparks (I would prefer one spark output per coil and not firing coils in parallel).
Traditional wasted spark systems have two plugs wired in series with the coil, like you see on EDIS and other systems. This way the wasted spark takes very little energy (there's very low pressure in the cylinder receiving the wasted spark so it takes very little energy to ionize the spark plug there)

ami8break · Post by **ami8break** » Sat Apr 09, 2005 4:55 pm

Hello Baldur,
if ion sesnsing is running one day then the ECU knows when it can *save* the wasted spark. At least SAAB did this more than 10 years ago.

Otherwise wasted spark with double ended coils is not the worst way to spark because when the waste spark is fired (arc) the voltage rises with ~doubled speed before it fires too.
»Horst

_Adrian_ · Post by **_Adrian_** » Sat Apr 09, 2005 9:06 pm

Great Thread guys keep it up

slow_hemi6 · Post by **slow_hemi6** » Mon Apr 11, 2005 3:22 am

Hi Horst, what I meant was that with the switching speed of the 2n3055 transistors you will get Radio Frequency noise probably around about 2Khz, There seems to be some confusion about the 2 sections of the CDI.
The first section is always a power supply. In sparkrite the 2 transistors oscilate the primary of the transformer and this generates a high voltage in the secondary that is rectified to DC by the 4 diode bridge rectifier.
The second section is the switching section. This section switches the high voltage stored in the capacitor to discharge into the coil.
This is common to all CDI. The variation comes in the type and metheod of generating the high voltage DC and the metheod of switching.
The two fets in the switching section of the silicon chip design is indeed to provide multiple switching and therefore multiple sparks (one being + and the next being - and so on) This if you read the text can be disabled.
The sparkrite switching circuit only switches once.
The silicon chip circuit is hard to get past 300v as this is part of the voltage regulation part of the circuit made up of the 4 75v zenners. it could be posible to include 1 more zenner and wind the transformer to output 375 volts.
Anyway I will try to help this discussion out but I am probably not the best person on the forum to do so. FACT. I tend to work stuff through on the bench and eventually end up with what I want safe or not. I must say that the voltages we want to use here are potentialy lethal and if something were to go wrong and a bystander touched the car and was killed,or someone was fiddling at the bench and was thrown into cardiac fibrilation then who's going to get the finger pointed at them?
NOT ME so experiment all you want but I am not telling or advising anyone to do anything.
just reread this and I was a bit tired!

aerowerks · Post by **aerowerks** » Mon Apr 11, 2005 9:26 am

Exactly my view. If you feel uncomfortable dealing with these voltages, DON'T. Let other people figure it out and make it safe to use. That is why I haven't posted any of the schematics, I want to make sure that it is absolutely safe before I do.
I have found a simpler circuit that may work slightly better for multiple channels.

Rick

ami8break · Post by **ami8break** » Wed Apr 13, 2005 4:07 pm

Hello Luke and Rick,
I read the Cap-dis-ignit.pdf aricle carefully and know the problems of the 2kHz but I thought it is worth to test since the owner of the Sparkrite CDI haven't complained about it - but I don't know if he's listing car radio. ;)

Yes you're absolutely right there is confusion about the interfaced and compability of the sections.

But now I understand! - I remember this typical 4 diodes layout is used in AC-->DC adapters but I wondered only why all CDIs have this.

Thank you also for the HV lethal warning. I can't develop any circuit and even I can't understand some simple but tricky circuits so I'm more careful with voltage than well educated people.
I have thought earlier how to feed the coil with ~400V - maybe a fatter shielded wire is enough. My CDI will be in the depth of engine bay so no danger for nosy people.

I'm looking forward for any circuits in the future - and I promise to be careful!

»Horst

zsilinszkyz · Post by **zsilinszkyz** » Thu Apr 14, 2005 1:08 am

A good advice: keep one hand in your packets when poking inside the circuit, if you have to measure something while it's live. The safest would be to discharge the caps before doing anything.
You can also read some general safety guidelines here.

One question, what coils do you want to use with the CDI ignition? As far as I know, the CDI requires different coil than the conventional ignition.

Zoltan

ami8break · Post by **ami8break** » Thu Apr 14, 2005 2:48 am

Helle Zoltan,

The safest would be to discharge the caps before doing anything.

I thought to do this. My idea is to add a quality push button (at the CDI-box) after the 1uF 400V capacitor (primary coil side) which shorts to ground. Is thsi what you meant?

@coil + CDI:
I read too about "special" CDI coils (MSD Blaster2) but some/most(?) aftermarket CDIs (MSD-6A, Cap-dis-ignit-CDI.pdf, Sirius...) do not require a special coil. Maybe if it is a very high energy system there could be crossfire in/around a traditional coil.
Of course an OEM setup like SAAB optimized their coils for heir DI (but not for real long life as you said).
Any (also TCI) coil should work fine with a DIY-CDI.

Do you know why SAAB CDIs require spark plugs with ressitor? This seem more important for me.

Thank you for the Safety guidelines link.

»Horst

zsilinszkyz · Post by **zsilinszkyz** » Fri Apr 15, 2005 1:59 am

Horst,

Well, almost. Shorting the cap is not really a good idea (it will burn you switch, quality or not). I'd rather use a serial resistor (say 10k/5w if I calculate it well enough, but please check that it really discharges the cap good enough before relying on it!!!), it will limit the discharge current. You can also use a 12v relay, so that you cannot forget it.

Regarding the resistor plug, one reason can be the lowering of RF interference. I've also found this interesting description of how the resistance affects the spark. Basically, the resistance limits the current and makes the spark longer.

Zoltan

ami8break · Post by **ami8break** » Thu Apr 21, 2005 7:25 am

Hello Zoltan,
I like the relay (+resitance) idea when ignition is off! Thank you!

Also, thanks for this intersting link. Maybe it is better for CDIs to 'slow down' but get a 'smoother' spark which helps ion sensing.

Reading about resistance in spark plugs (and wires) I remember that my current single coil solution is dangerous:
http://www.msefi.com/viewtopic.php?t=7505

»Horst

dart73 · Post by **dart73** » Mon Apr 25, 2005 3:10 pm

Hi people... I started this topic but.. forgot about it... in fact was busy for a while....

My question... this circuit .pdf I´ve posted would work fine?? My idea was to change the Zeners for 125V units (I don´t know if there´s Zeners with this Voltage) and change the transformes turns to rise the output voltage to 500V as seen on the MSD boxes... also chage the capacitors to 500v and so on..

What do you think?? What should be the problem of using these voltage in the output?

aerowerks · Post by **aerowerks** » Mon Apr 25, 2005 8:39 pm

replacing the zeners with 125v setting is little strange, just put in more 75v ones to get the voltage you want, the trouble would be in the lower "multispark" section, everything would have to be redesigned with new parts to withstand the higher voltage,

Rick

dart73 · Post by **dart73** » Tue Apr 26, 2005 11:19 am

Horst,

here we go....

I´ve drawed it in Corel Draw... because I hadn´t another software here... so.. I´ve double checked here.. but I need you to check for errors... and I need to know if the resolution it´s good for printing... or I can send another file in higher resolution...

Fernando

* now I´ve put a .gif and a .bmp files.... choose your flavor...

dart73 · Post by **dart73** » Tue Apr 26, 2005 6:07 pm

Horst,

I´ll check the size of the print as I have some time... I think I can do these tomorrow,..

Cya

ami8break · Post by **ami8break** » Wed Apr 27, 2005 2:43 am

Hello Fernando,
thank you for doing a great job!

Originally I planed and would had been happy to find/get just a simple CDI, but with your layout it makes more sense to try the luxury DIY CDI.

»Horst

PS: If European MS guys are interested in such a PCB please check
http://www.msefi.com/viewtopic.php?t=8070 .

ami8break · Post by **ami8break** » Wed Apr 27, 2005 6:01 pm

dart73 wrote:My idea was to change the Zeners for 125V units (I don´t know if there´s Zeners with this Voltage) and change the transformes turns to rise the output voltage to 500V as seen on the MSD boxes... also chage the capacitors to 500v and so on..
What do you think?? What should be the problem of using these voltage in the output?

Hello Fernando,
today I reread some of my collected notes. At http://www.siliconchip.com.au/cms/A_30315/article.html a guy asked:
How to increase Multi-Spark voltage
I am interested in building the Multi-Spark CDI project from the September 1997 issue of SILICON CHIP. I was wondering about modifying it slightly. I'm wanting to increase the primary voltage from 300V to around 425V or so. Is this possible? The reason for this is to increase the output energy from 45mJ. Most commercial units put out 420V to 525V for the primary.

And SiliconChip replied:

The voltage can be increased by another 75V using an extra 75V zener in series with ZD1-ZD4. We do not recommend going above this voltage as the capacitor is not rated for more volts. You will need to add about 50 more turns on the secondary of T1 as well.

I guess this is what we want!

But now we have to look for a higher rated capacitor.

A little bug was reported at http://www.siliconchip.com.au/html/indexes/ne-97-98.htm :
Transistor Q1 in the impulse tachometer circuit on page 30 should be labelled a BC327 and not BC337 as shown.

»Horst

dart73 · Post by **dart73** » Wed Apr 27, 2005 6:34 pm

Hello Horst,

Sorry.. I couldn´t check the board draft today because I´d too much work.,... Will do it tomorrow...

Fernando

dart73 · Post by **dart73** » Thu Apr 28, 2005 4:49 pm

ami8break wrote: The voltage can be increased by another 75V using an extra 75V zener in series with ZD1-ZD4. We do not recommend going above this voltage as the capacitor is not rated for more volts. You will need to add about 50 more turns on the secondary of T1 as well.

I can modify the circuit and add 2 more Zeners.. then... the output voltage on the primary of the coil should go to 450V.. so.. I need to recalculate the number of turns in the transformer... and find a 500V capacitors... And who don´t want these changes... just jumper the additional Zeners place..... What do you think people!?!?!

Fernando