CDI ignition and MSnS

[ami8break]

Hello Fernando,
yeah - why not, each feature makes this CDI more flexible.

I haven't studied the circuit layout, but I'd like to switch easier between multi spark and 'dual' spark (SC pages 24, 25, 26). I thought to place some jumpers to do this without resoldering components.

For my purpose (ISP) I'd like to get only one spark. Is this (im)possible? I guess Q6 and Q7 would be the key...

Today I looked for a transformer core and found some cheap suitable types but I miss measurements --> I'll look harder.
In another shop I found some plug&play transformers. There pins are compatible with the CDI PCBs --> seem to be a standard. --> some dismanteling work required, also I don't know if this is possible without destroying the frame. I can't rember that I have dismantled a transformer yet.

Has anyone studied the BOM (SC page 25)?
The scanned text has some OCR errors. Can anyone of the EEs here check them? Thank you.
I miss also some details of various components. For example I don't know what are the specifications of L1? Ok, dimensions can be taken from Fig.7 (SC page 26) but what's about the windings, uHenry...?

»Horst

[ami8break]

Hello,
This kit would be available at http://www.dse.com.au/cgi-bin/dse.store ... View/K3307 .
I asked DSE for some details of the kit and got page 1-9 from their manual, you can download it here: http://megasquirt-de.serviceline.ch/suc ... age1-9.zip
Any idea to get he missing pages of the manual?
Luckily there is the BOM (page 7)!!

The article was also published in "Electronic Projects For Cars Vol2" (less than 18ASD including shipping), if anyone can find on the shelf, we miss the pages after the small headline "Construction". Some pictures are not in a very good quality so I'd ask for high resolution scans of figure 7(!), 8, 9, 10, 11, 12, 13, 14(!)
Thanks.
»Horst
My hungry mailbox: ami8ATgmx.net AT=@

[slow_hemi6]

As always Horst you seem to be a 1st class scrounger!
75dpi good enough?

[zsilinszkyz]

Regarding the cap discharge, I've found this page.

Zoltan

[ami8break]

Hello Zoltan,
thank you - a really helpful and intersting link. Now I'm afraid just to buy and touch any capacitor. ;)

I guess the only dangerous capacitors are the 1uF, 275V. It is a "LV" type which need 2 to 4kOhm for save discharge (refering to the website).

I read that the CDI should be turned on for some seconds before starting the engine to 'fill' the capacitors --> I'd suggest to discharge the capacitors only if the CDI box will be removed/opened.

What do you think about to place a hidden (temperature proof) 4pin switch at the side of the box. When the user wants to open the box he must short the circuit so that both capacitors can be discharged (1 circuit after the switch --> 2 pins connected to each capacitor and the others connetcted to share 1 circuit)?.

What's about the other capacitors? they're rated at lower voltages but the capacity is much higher: 2x 100uF and 2x 10uF

»Horst

[jsmcortina]

How about a microswitch that discharges the capacitors if the case is removed?

[ami8break]

Hi James,
you think about an anti-theft device on penalty of death? ;)
Or does "case" just includes the cover/lid on the top? A push button which shorts the circuit if the cover/lid is removed?
»Horst

[zsilinszkyz]

Horst,

Better safe than sorry, at least now you know what to look out for.
The 16V rated capacitors don't pose any threat if you accidentally touch them, but don't try to lick them.
Regarding the switch, the best would be something, that you cannot forget to use. As James has proposed, you can install a switch (e.g an SPDT microswitch) that is activated by the cover. If you remove the cover, the other circuit is activated, which you can use to discharge the cap.
Another question is, what happens if the cap is charged and you remove the coil? Will that wire be able shock you?

By the way, are you sure about the 1u/275V cap you mention? I thought you wanted 400V, for which this cap is insufficient.

Zoltan

[ami8break]

Hello Zoltan,
ha ha I *plan* not to lick my CDI even if I'm very excited!

@Discharge switch/circuit:
Today I dismantled my sinus 12VDC-->220VAC converter (because it switches off power at ~12V!) and saw the same capacitor which is in the CDI. "1u0 275V X2 MKP Philips 9850" is printed. I use "u" for Greek "my" here.
At the board there is a warning to "wait 3min!" an there is not discharging circuit included.
I'll put in a switch inside of the box.

@Removing the coil:
I understand CDI in that way that the enrgy is charged in the capacitor and the coil transforms it when the spark occurs. Traditional ignition charges energy in the coil.
But I'm not sure!

@1u/275V cap rating:
It was not my idea to increase the voltage just to add another diode:

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 works because the 300V ar not DC --> the average is below 275V. Are there any suitable higher rated capacitors available? My local dealer told me that they're not used today anymore --> difficult to find.

It's slightly off-topic but important for ion sensing project (ISP): How can I share this 300V for ion sensing if this a high frequent (20kHz) voltage? Would this influence the measuremnt? Ion current is about 10mA.

@layout news:
A well educated member of the German MS forum is willing to make a layout file and'll make some boards with his special milling machine.
He'll include some jumpers to make it easy to select between MultiSpark and DualSpark, also the board will support a cap discharge resistor.

@DualSpark:
Is it possible to fire only 1 time --> "SingleSpark"?
I'd like it for ion sensing! Has anyone of you an idea how to modify the board?

»Horst

[zsilinszkyz]

@Discharge switch/circuit:
It might be that there's a resistor in parallel with the main cap, that's why you have to wait for 3 mins.

@1u/275V cap rating:
I thought you wanted to build the circuit that is on the first page of this topic (with a 1u/400V cap). The other circuit has a 1u/275VAC cap (it's probably equivalent to a 400V DC, but I'm only guessing). I'd say you have to size voltage ratings for peaks, not averages (and put some margins as well), so if I were you I'd choose a 630V cap (especially if increasing the output voltage).

You should find another parts supplier, the shop I'm buying parts has loads of high voltage caps, e.g. "1uF 400V 9# FOL . 10% MKT * MKS4 (WIM) 26.5x21x11mm" for 0.5 EUR, "1uF 630V 11# FOL . 10% * MKP4 (WIM) 31.5x24x13mm" for 1 EUR and even "1uF 1000V 15# FOL . 10% MKP * MKP4 (WIM) 41.5x29x17mm" for ~2.5 EUR.

@Removing the coil:
I wanted to ask what if you remove the coil and the cap is still charged? Is it possible at all?

Zoltan

[dart73]

"1uF 400V 9# FOL . 10% MKT * MKS4 (WIM) 26.5x21x11mm"
Zoltan

What is this MKP and MKT ?? Is the shape (case) of the capacitor??

The original project was going to use 275V capacitors... because it should be regulated to 300V... and as we want more tension... we´re putting two to more 75V Zeners... increasing the number of turns in the transformer... and rising the voltage of the capacitor.... I think this 630V should be fine... or something above 450V...

Fernando

[ami8break]

Hello Fernando,
*proud* to tell you that MKP is an akronym for Polypropylene film and MKT is for Polyester film types - but don't ask me why.
»Horst

[dart73]

Hello Fernando,
*proud* to tell you
»Horst

Proud? Are you crazy??

But.. the working of the capacitor...

if we have the same voltage and capacitance in both... can we change a MKT for a MKP... are they interchangeable????


Fernando

[slow_hemi6]

1uf is 1uf, really should'nt matter with the times these will be holding charge. I sometimes use 22uf 630v capacitors in discharge lighting. They are about the size of a military canteen.
About adding the extra diode..... The winding of extra turns on the output will step up the output voltage. The extra diode causes the voltage regulation to cut in at 75v higher. There is not much point putting out extra voltage if the reg is limiting it to 300V.
Horst, the bridge rectifier makes that output DC. The smoothing capacitor( 1uf 275v after the bridge) would need to be rated for the higher voltage as well as the output capacitor.
The cars coil is just another step up transformer.Transformers only work with AC. It is the change of state that induces(magneticly)the voltage in the secondary. Standard ignition the change of state is 12v to 0v when the points open. CDI the change of state is 0 to 300 or more volts when the capacitor discharges through the primary.

[Marcus]

After a quick check in my electronics catalouge:
KT (M-metallic polyester) for filtering or decoupling application.
KP (M-metallic polypropylen) for pulse and audio applications.
KC (M-metallic polycarbonate) for oscillators.

[dart73]

Ok.. thanks Marcus

[slow_hemi6]

Fernando I seem to live by your signiture.
My MOPAR was rear ended and after taking all the good gear out of the shell I now have NO CAR
Lucky my wife has 2 cars and my work gives me 1.
MOPAR or SOMEBODY ELSES CAR!

[dart73]

I´ve started doing my CDi module... the only parts it´s missing it´s the transformator... and some semiconductors that I haven´t found in the local store.... I´ll try to find it in another store....

Anyone have any sugestion about a switch to discharger the capacitors.... these are 630V capacitors.. but I´ll limit it in the transformator.. and 6 75V Zeners....

Thanks,
Fernando

[olsonjus]

How hard would it be for me to make a 5 channel CDI from the above instructions? No one sells a 5 channel cdi so I'm kinda SOL unless I pony up for a 8 channel.

Regards,
Justin

[aerowerks]

Don't limit the transformer, it is better to have higher possible output voltage and limit it by the zeners, it will insure faster charging for the capacitor even under heavy load,
For the 5 channel CDI all you have to do is build five copies of the lower end of the circuit and control each firing SCR separately (not sure why since the MS'n'S-E cannot control more than four channels)