photo sensor ignition

[Benta]

"it´s not that sensitive. casing is shielded. Osciloscope didn´t show any high voltage spikes or anything, signal is clean. Problem is that pull rate of hall senosor is too low(on scope 1.5kHz right now, but datasheet says it should be 12kHz)."

That's somewhat in contrast to this statement from you:

yes, it was originaly there, but i had problems with reading and converting it to digital. There was around 60V and also negative voltage. so my tranzistors were not happy even with 100k rezisotor. Bike I´m working on is jawa babetta 210 typ 50

So what's true?

[tomcer34]

It would help if we knew what engine this is going on, a moped or what and what the original ignition system was. No idea what OP is using for the magnet either. How about some pictures. Otherwise this guessing is just silly.
Simple ignition systems have irregular cam lobe and staggered pickup coils to achieve timing advance and rev limiting.

there is original diagram of it. It is simple tyristor ignion system. Mopped is Jawa 210. It´s two stroke 50cc engine that has been modify. I don´t need a rev limiter.
there is few phtotos and pictures. If u would need more, let me know

[tomcer34]

"it´s not that sensitive. casing is shielded. Osciloscope didn´t show any high voltage spikes or anything, signal is clean. Problem is that pull rate of hall senosor is too low(on scope 1.5kHz right now, but datasheet says it should be 12kHz)."

That's somewhat in contrast to this statement from you:

yes, it was originaly there, but i had problems with reading and converting it to digital. There was around 60V and also negative voltage. so my tranzistors were not happy even with 100k rezisotor. Bike I´m working on is jawa babetta 210 typ 50

So what's true?

that was for induction sensor. Signal is perfect, as i said, but pulling rate of hall effect sensor is low and i dont know why. By qoute " i had problems with reading and converting it to digital" i ment, when i was using induction type sensor, that was originaly there, i had problems with unpredictable voltage. right now it´s based on hall sensor. Sorry for confussion i made. My english is not the best 

[eugene]

Variable reluctance sensors require special signal conditioning. Typically, they look for a zero crossing.

Either Hall Effect or optical sensor should be fast enough. If there is a time delay that is constant under all conditions, then that can be compensated for in the microcontroller.

My guess is that the engine will not rev above 5k RPM because the spark timing is not advanced far enough, not because the crankshaft position sensor is too slow.

[langwadt]

Variable reluctance sensors require special signal conditioning. Typically, they look for a zero crossing.

I know I guy that has been building ECUs for probably 30 years, I think most of his designs use a resistor into a 74hc14 biased to VCC/2 with another resistor as signal conditioning and that works with pretty much any sensor VR or Hall

My guess is that the engine will not rev above 5k RPM because the spark timing is not advanced far enough, not because the crankshaft position sensor is too slow.

yeh, the original ignition looks mostly like capacitor discharge, so the advance is pretty much fixed at any RPM
with a sensor into a 555 for dwell time flyback, the ignition will be retarded with increasing RPM

[floobydust]

Small engines use the magnetic circuit to achieve timing advance in firing the SCR. There's likely more than one magnets in the flywheel as well. OP did not give info about whatever the Hall sensor is picking up.

Running an inductive sensor into a Schmitt trigger does not work well, especially with VR you get a phase shift with speed and need compensation which automotive VR sensors incorporate. It would be OK with a digital (Hall) sensor though.

pic from Silicon Chip Magazine

[langwadt]

Small engines use the magnetic circuit to achieve timing advance in firing the SCR. There's likely more than one magnets in the flywheel as well. OP did not give info about whatever the Hall sensor is picking up.

Running an inductive sensor into a Schmitt trigger does not work well, especially with VR you get a phase shift with speed and need compensation which automotive VR sensors incorporate. It would be OK with a digital (Hall) sensor though.

just just fine with VR crank and ABS sensor and hall cam sensors

[floobydust]

A VR position sensor and a speed sensor are different i.e. MAX9924 Variable-Reluctance Sensor Interface includes Adaptive Peak Threshold for the threshold shift. Without it you'll get a phase shift which is bad for timing, and not important for speed sensing like ABS.
It also depends on how many teeth you're dealing with.

[langwadt]

A VR position sensor and a speed sensor are different i.e. MAX9924 Variable-Reluctance Sensor Interface includes Adaptive Peak Threshold for the threshold shift. Without it you'll get a phase shift which is bad for timing, and not important for speed sensing like ABS.
It also depends on how many teeth you're dealing with.

except at starting the voltage is tens of volts, all you want is the zero crossing. And if there is any speed dependent shift it will be incorporated in you ignition map

[tomcer34]

Variable reluctance sensors require special signal conditioning. Typically, they look for a zero crossing.

Either Hall Effect or optical sensor should be fast enough. If there is a time delay that is constant under all conditions, then that can be compensated for in the microcontroller.

My guess is that the engine will not rev above 5k RPM because the spark timing is not advanced far enough, not because the crankshaft position sensor is too slow.

timing is on spec with original ignition. i tried a lot of possitions. Stock work the best. I even tried extreme of both timings. Ignition timming in high rpm will be done with another NE555 and digital potenciometer and arduino. That part of my project works well, only 6ns delay and in engine it doen´t mean any difference. But now it´s not part of schema/diagram, right now it´s not used, because I tried deleting any possible mistakes, but this was not one of them.

[tomcer34]

Variable reluctance sensors require special signal conditioning. Typically, they look for a zero crossing.

I know I guy that has been building ECUs for probably 30 years, I think most of his designs use a resistor into a 74hc14 biased to VCC/2 with another resistor as signal conditioning and that works with pretty much any sensor VR or Hall

My guess is that the engine will not rev above 5k RPM because the spark timing is not advanced far enough, not because the crankshaft position sensor is too slow.

yeh, the original ignition looks mostly like capacitor discharge, so the advance is pretty much fixed at any RPM
with a sensor into a 555 for dwell time flyback, the ignition will be retarded with increasing RPM

i didn´t notice any dwell time flyback. Any delay in circuit is around 6ns as far as i messured. Timing is on the spot (1.5mm before top to be exact). But hall sensor can react fast enought in changing magnetic fields. Also as u said, in original ignition advence of timing was fixed, also right now it´s fixed in all frequency i messured. Measuring was done with Hz generator to remove possible mistakes I coud make with hall sensor. Right now i need spark to fire when it´s need to be fired

[tomcer34]

Small engines use the magnetic circuit to achieve timing advance in firing the SCR. There's likely more than one magnets in the flywheel as well. OP did not give info about whatever the Hall sensor is picking up.

Running an inductive sensor into a Schmitt trigger does not work well, especially with VR you get a phase shift with speed and need compensation which automotive VR sensors incorporate. It would be OK with a digital (Hall) sensor though.

pic from Silicon Chip Magazine

hall sensor is picking up original magnet on flywheel, also hall sensor is in the same possiton as was original induction sensor used with tyristo igniton. Hall sensor that i´m using should be digital acording to datasheet. but there is a few version of it so i may be wrong, but also i used comparator to realy make it to digital signal

[tomcer34]

A VR position sensor and a speed sensor are different i.e. MAX9924 Variable-Reluctance Sensor Interface includes Adaptive Peak Threshold for the threshold shift. Without it you'll get a phase shift which is bad for timing, and not important for speed sensing like ABS.
It also depends on how many teeth you're dealing with.

except at starting the voltage is tens of volts, all you want is the zero crossing. And if there is any speed dependent shift it will be incorporated in you ignition map

so i have a wrong sensor for my project ?

[floobydust]

I don't think there's anything wrong with the Hall sensor and you can run the same sensor off some magnets on a hand drill or fan to prove it. The Hall sensor already has a comparator so the LM339 is not needed for it.
Or you have a noisy 5V causing trouble, or the other coils (CDI and lighting) and magnets are causing side-effects. The Hall sensor wants the magnet perpendicular to its face, not parallel to it so is it even oriented properly?

But maybe the circuit's approach is not going to work?
First, the 555 is a fixed pulse-width (dwell) time- which does not cover both low speeds and high speeds.
You need the coil energized, storing energy BEFORE the spark event. The CDI module does this by storing energy in a HV capacitor.
A good dwell time at low speeds means the 555 cannot re-trigger at high speeds, there is no time. So it will stay on and there is no spark. Is this what is actually going on?

This is a small 2-stroke engine, I would think it really needs timing advance. Here some 50cc are limited to 30MPH.

edit: the rotor seems to have 7 magnets- 6 are for lighting and CDI power, and one just for ignition timing.

[tomcer34]

I don't think there's anything wrong with the Hall sensor and you can run the same sensor off some magnets on a hand drill or fan to prove it. The Hall sensor already has a comparator so the LM339 is not needed for it.
Or you have a noisy 5V causing trouble, or the other coils (CDI and lighting) and magnets are causing side-effects. The Hall sensor wants the magnet perpendicular to its face, not parallel to it so is it even oriented properly?

But maybe the circuit's approach is not going to work?
First, the 555 is a fixed pulse-width (dwell) time- which does not cover both low speeds and high speeds.
You need the coil energized, storing energy BEFORE the spark event. The CDI module does this by storing energy in a HV capacitor.
A good dwell time at low speeds means the 555 cannot re-trigger at high speeds, there is no time. So it will stay on and there is no spark. Is this what is actually going on?

This is a small 2 stroke engine, I would think it really needs timing advance. Here some 50cc are limited to 30MPH.

edit: the rotor seems to have 7 magnets- 6 are for lighting and CDI power, and one just for ignition timing.

5V it´s checked and it´s clear with new caps. Hall sensor is oriented properly and picking only timing magnet.
i used 8600uF cap bank made from smaller caps, so there is energy before spark.
u may be right with ne555 re-triggering. When is NE555 oscilating at 10kHz circuit act diffrently, but there high Hz cant take my ignition coil. So there goes project. never mind. Is there way i could used this circuit, but insted of "turnig on and off" NE555, turnig off and on something different? for example tranzistor for ignition, but NE555 would be still oscilating, or adding one more tranzistor before existing one. i will put picute to see what i mean. i need to get this working and remaking this is not possible, because deadline in school is 11.2 XD

[langwadt]

I don't think there's anything wrong with the Hall sensor and you can run the same sensor off some magnets on a hand drill or fan to prove it. The Hall sensor already has a comparator so the LM339 is not needed for it.
Or you have a noisy 5V causing trouble, or the other coils (CDI and lighting) and magnets are causing side-effects. The Hall sensor wants the magnet perpendicular to its face, not parallel to it so is it even oriented properly?

But maybe the circuit's approach is not going to work?
First, the 555 is a fixed pulse-width (dwell) time- which does not cover both low speeds and high speeds.
You need the coil energized, storing energy BEFORE the spark event. The CDI module does this by storing energy in a HV capacitor.
A good dwell time at low speeds means the 555 cannot re-trigger at high speeds, there is no time. So it will stay on and there is no spark. Is this what is actually going on?

This is a small 2 stroke engine, I would think it really needs timing advance. Here some 50cc are limited to 30MPH.

edit: the rotor seems to have 7 magnets- 6 are for lighting and CDI power, and one just for ignition timing.

5V it´s checked and it´s clear with new caps. Hall sensor is oriented properly and picking only timing magnet.
i used 8600uF cap bank made from smaller caps, so there is energy before spark.

gotta show how you have it all connected, 8600uF makes no sense it's probably a few uF in the original thyrister ignition

[eugene]

If you are going to use an Arduino for timing, why not use it to generate the pulse dwell too?

555's seem great when there is no other way. But Arduino is an easier way.

[tomcer34]

If you are going to use an Arduino for timing, why not use it to generate the pulse dwell too?

555's seem great when there is no other way. But Arduino is an easier way.

i didnt want to risk damaging my arduino when i was strating this and after a while it was easier to let it sit there. But i will try it with arduino now.

[tomcer34]

I don't think there's anything wrong with the Hall sensor and you can run the same sensor off some magnets on a hand drill or fan to prove it. The Hall sensor already has a comparator so the LM339 is not needed for it.
Or you have a noisy 5V causing trouble, or the other coils (CDI and lighting) and magnets are causing side-effects. The Hall sensor wants the magnet perpendicular to its face, not parallel to it so is it even oriented properly?

But maybe the circuit's approach is not going to work?
First, the 555 is a fixed pulse-width (dwell) time- which does not cover both low speeds and high speeds.
You need the coil energized, storing energy BEFORE the spark event. The CDI module does this by storing energy in a HV capacitor.
A good dwell time at low speeds means the 555 cannot re-trigger at high speeds, there is no time. So it will stay on and there is no spark. Is this what is actually going on?

This is a small 2 stroke engine, I would think it really needs timing advance. Here some 50cc are limited to 30MPH.

edit: the rotor seems to have 7 magnets- 6 are for lighting and CDI power, and one just for ignition timing.

5V it´s checked and it´s clear with new caps. Hall sensor is oriented properly and picking only timing magnet.
i used 8600uF cap bank made from smaller caps, so there is energy before spark.

gotta show how you have it all connected, 8600uF makes no sense it's probably a few uF in the original thyrister ignition

origanly there was 4uF, but i made it to 8600uF because it was pulling too mutch current and it made my voltage regulation nightmare. But with this huge capacitance, is voltage regulation "perfect", no huge spikes or drops in voltage, 30mV at most. There is my PCP layout. Tranzistor and caps are on another board(handmade) so there would be less noise, to base of tranzistor is going shielded wire(from brokend osciloscope probe). And, is arduino fast enought for 12000RPM, time to react to hall sensor and send signal to the tranzistor?