The timer board can draw power from the HV ignition board so no need for a separate battery.

The closest thing I did was dip the whole thing in polyurethane. Once dried it will keep the parts from vibrating loose.

Is there any way for you to make post more clear schematic?

http://www.electronics.gompy.net/cditci/

No problem, the timerboard don't use much current, it's the HV=powerboard wat cunsume.

Don't doit, epoxy will break the components away from the PCB.
Use silicon or other flexible kits.

Thoose pins are used for in circuit programming.
If you put the hole pcb into flexible kit, its impossible to reprogram the pic if you don't have this pins.

Ask why the 'A' why not 'B.<span class="short_text" id="result_box"><span title="A megold&aacute;s lehet ez ?" style="background-color: rgb(255, 255, 255);">"The solution" to this?</span></span><span id="result_box" class="short_text"><span style="background-color: rgb(255, 255, 255);" title="A megold&aacute;s ?"> </span></span> Thanks nyemi.

John, Charlie thanks for the tips, i did not try lowering C4 but i went up to 1uF not down as the spark wouldn't wont to be any less intense now,

Charlie yes i have circuit on my test bread board ......do you think what im thinking that the wires are to long etc......

i had alot more luck after my last post in isolating the SCR with more caps and another resister and achieved a quick test run around 20k rpm,



Quote By azalner 3. I haven't been able to figure out where pin 4, 12 and 13 go on the PIC. Can anyone help?

They are used for programing the pic (rob has answered sorry)




John does your circuit stop working at 10,000 rpm, does it start missing or lock the SCR around that RPM ???

i have use a 16F628A for a 16F627A circuit as was told they are the same, and it worked fine

sorry for video it was hard to hold the speed 400 motor as it had the magnet taped to the shaft and the vibration was huge

http://yfrog.us/1ndscn2484z

brett

the wires may offer a little resistance compared to pcb traces,but nothing to worry about. With my setup not sure what rpm,but around 12K I just loose spark. As mentioned going to a bigger cap for C4 it takes more time to charge it and unless you speed up the oscillator you will lose spark at high rpm. I would try a 400 volt cap and less then .47uf

nyemi i am sorry i dont understand fully but i think you are asking why there are two different circuits ???

there is a positive or negative pulse coming from each different circuit ......depending how you have set up your SCR

in your picture "A" is positive and "B" is negative pulse

hope that makes scents if that was your question

brett

With B the ground isn't zero ground but +0,6Volt.

Charlie i use .47 cap 630v.... i could put two .47 in series to give me 235nF......but cant remember iv you half the volts or double ?

brett

One thing i did notice is if you use a larger cap say 470uF 50 volts across the power supply it quietens down the coil heaps......, im using a LM350t Regulator so
may need more filtering than johns nicad battery pack

<span id="result_box" class="short_text"><span style="background-color: rgb(255, 255, 255);" title="&Eacute;n nem tudni j&oacute;l?">I do not know well?</span></span><span class="short_text" id="result_box"><span title="&Eacute;n nem l&aacute;tni J&oacute;l?" style="background-color: rgb(255, 255, 255);"> </span></span>Thanks nyemi.

Sam is that the 56us delay you where trying to reduce ???

rob why does SCR triger after the gap and not on the first pulse ?


brett

Were you able to open up the .pdf file? The schematic is much more legible. Please review to see if there were any errors before I start laying out the PCB.

One other question - what is the purpose of the LED "flashlight"? Is this just for testing? Do I need it if I use a scope?

All components on the HV side are rated 600 volts or better; 400 volt ratings are just on the ragged edge.

Any suggestions for the coil & plug cap? Does it need to be shielded? The OEM junk was shielded.

Thanks

Al

Brett.. my circuit will generate such a weak spark after 10,000 rpm that it seems to just quit, touch the spark gap if you don't believe me.. it'll still bite ya!
The cap recovery time is too slow after that speed.. Since I never intended to go beyond that range it never bothered me.. I used to run it on a tired old K&B .40 engine that ran up to 11,500 but the spark on a NGK-ME-8 gap of only .20 still let it fire...so it kept right on running. A larger gapped plug would have just quit. I then started running only weedeater motors on ignition and haven't had a problem with them at up to 8,500 rpms..
You could drop the .47 to about .33 and still get performance levels you need at higher rpms though. I have tested that value and it did work. Without anything but a crappy VOM here I trusted my eyes and ears for the spark. Everyone seems to have correct solutions though and I agree with them all..

John

The C into the fireline will be grounded and the puls will be much higher to fire the scr.
I don't tnink the scr fire after the gap......I don't see this on the scope.
I think you mean the scr fire the coil after 1 turn.....thats normal, the timer has to calculate the delay and that can't be done into the first turn.

The large cap you mentioned across the power supply lines would definitly help quiet things down.. it acts like a ripple filter keeping the power at the same level for the next firing of the plug..
If you scoped the + wire without the cap in place, you'd see an awful low voltage dip when it fires...due to the fact you are in effect stopping the R/C oscillation circuit with a dead short current draw. This is why some transistors run hot...excess current draw.
My boards now have only a 2.2uf cap to filter..it used to be 100uf at 16 volts.
I used to try for the highest and most powerful spark I could get, but have since learned that humongous RFI is the result, which killed our radio signals on our planes.. So I lowerd it to fit the needs and left it alone for the last 10 years..
Feel free to add a large value cap to the circuit for filtering in your application.

John

Hello Al,

No. I opened the attachment and it wasn't any better. 4oov should be ok. At 600 volts all sorts of weird stuff happens. So if you can wind a transformer and make it put out 400 volts then you will be ok. Is this going on a model airplane? if so then I think if you can shield the coil wire then you will be better off.

<span id="result_box" class="short_text"><span style="background-color: rgb(255, 255, 255);" title="Alkalmaz">Apply</span></span> Oshon pic simulator ide.Time<span class="short_text" id="result_box"><span title="algoritmus" style="background-color: rgb(255, 255, 255);"> algorithm</span></span>:testfunc4=100uS,old file=65uS(65uS~4xTMR2_16uS!!!). Link:http://www.oshonsoft.com/pic.html

The 56us delay is actually a lot longer the way I use it. A coil spark needs more time to burn the spark then a CDI (as far as I know), so I use values over 1ms in the off-delay. This should not affect the dealy in the timing calculation though.
Just to explain it briefly. The delay value there is to keep the output low for a specific time, to give the spark time to burn before the output is going high again.

The delay I'm worried about is the 'processing delay' due to the number of cycles the processor needs until if actuates the output. The way I test this is by setting all values in tspark to 0, and then measure the delay between input and output.
This delay will always be there even if tspark value is 0. So, even if the delay is set to 0 (full spark advance) the spark will be delayed.
The debugger also tells you the processing time of each step, but when I compared the theoretical value with the measured value, I found the measured value to be slightly higher (5-10us).

There are definitely more delays in the circuit than just the processor. The hall sensor gives a delay too, and that depends on what sensor you use. The sensor I'm using gives a typical delay of 0,2us and maximum of 2us according to the data sheet. Then there will also be some delay in the ignition circuit, if it's a CDI or a coil. I don't know what the delay for the CDI is, but for a coil it is at least 10us as far as I know.

To conclude this, the trigger needs to be set XX degrees in advance of the maximum ignition angle you want. The amont of 'pre-trigger angle' needed is based on the maximum rpm and the total delay in the system (trigger+control board+ignition system). This way the actual timing advance should be the same as your advance curve.

The way it has been, the ignition angle is progressively retarding with RPM even if you had is set to a constant angle.
This is not a code problem really, you just need to move the trigger, and make a compensation calculation for triggaernangle and delay in the excel sheet.
However, the code should be kept as efficient as possible to minimize the delay. If delay goes over 100us, the trigger needs to be set very far ahead fo handle high rpm!

Sam you have your work cut out for you.......hope you are young haha.....good on you

does any one know what would be a more robust SCR or can i use a IGBT driver.....the BT151 is easy to damage when you are experimenting.....and could the lockup
of the SCR be part of the way the BT151 works when a transistor or mosfet would be stronger


brett

Brett,

I think you can use a mosfet. choose a 400v or something higher.

Why a scr ?
When the C unload over the coil, the Voltage behave reverse - plus will be minus and minus will be plu.
The scr is shutdown if the Voltage behave reverse, a scr lookslike a diode - the Voltage can go from Anode to Katode.
Ofcause you can use a IGBT, but then you need a cicuit to shutdown the IBG and protect him agains the reverse Voltage.
Into a TCI it's no problem to use a IGBT.

<span class="short_text" id="result_box"><span title="Application note" style="background-color: rgb(255, 255, 255);">Help.( figure2.3.-figure4.5.!!) Application note: capacitive discharge ignition.</span></span>

Hi nyemi,

Yoour attachment did not come through. I don't see anything.

@Brett, into this schematic they use a IGBT.

Do you have the latest Adobe .pdf? I had no problem downloading.