VR from solid state lawn mower coil

[H2active]

I would like to run a MS2 - V3.0 board on a generator engine the coil is a solid state item controlled by a magnet (N and S poles next to each other) on a flywheel. Does anyone know what kind of signal is generated on the kill wire when it is open? Can this be used to drive the VR input to the MS2?

Thanks for replying if you know, I may have to dust off my old HP o scope to get the answer.

[old guy]

Don't do it. The kill wire on these ignitions have some pretty high voltage on them. It would probably fry your VR circuit.
Seeing as how you already have the magnets on the flywheel , I would use a hall effect sensor.

[H2active]

Thanks old guy you are probably right. I’m not to savey on hall effect switches is there a model that might work? I’ll do more searching on this. One other option is to use a magnetic reed switch and see if I only get one point break per rev and not 2 because of the 2 magnetic poles.

[old guy]

Don't use a reed switch, it will not be able to keep up with the speed of the engine. If you are not that electronics savvy , your best bet would be to purchase a hall sensor from someone like DIY AUTOTUNE. That way you will be sure that it is something that is compatible with your MS unit.
Just out of curiosity, why are you putting an MS on a generator and what kind of engine is it.
I work on a lot of this stuff and might be able to help you out.

[DonTZ125]

It sounds like this beast is an AC-CDI; the voltage from the charging coil is probably 250-300vac. You COULD try a limiting circuit of a 1k resistor leading to two 1N4007 diodes; this will allow you to use the VR circuit on the V3.0 board.

The diodes are wired tip-to-tail pointed in opposite directions; one end of the diode pair leads to one end of the charging coil through the resistor, while the other end of the diode pair is wired to the other pole of the charging coil. The VRin wire is connected to the same end of the diode pair as the resistor, while the other end of the diode pair is wired to the MS sensor ground. This will clip the maximum voltage to the Vf of the diodes (1.1v, IIRC), while also limiting the current through the wiring to .25-0.3 amps. This should give a true 'zero-crossing' signal between the peaks that the VR will read quite happily.

[old guy]

It sounds like this beast is an AC-CDI; the voltage from the charging coil is probably 250-300vac. You COULD try a limiting circuit of a 1k resistor leading to two 1N4007 diodes; this will allow you to use the VR circuit on the V3.0 board.

The diodes are wired tip-to-tail pointed in opposite directions; one end of the diode pair leads to one end of the charging coil through the resistor, while the other end of the diode pair is wired to the other pole of the charging coil. The VRin wire is connected to the same end of the diode pair as the resistor, while the other end of the diode pair is wired to the MS sensor ground. This will clip the maximum voltage to the Vf of the diodes (1.1v, IIRC), while also limiting the current through the wiring to .25-0.3 amps. This should give a true 'zero-crossing' signal between the peaks that the VR will read quite happily.

I would almost bet that this is an all in one ignition module as used on B&S and a lot of small industrial engines. This thing is more like an electronic magneto than an AC CDI.All that the kill lead does is ground the primary side of the ignition coil. There is no kind of VR signal on this wire. I don't see of any way you could use the standard ignition module to trigger a MS.
If he tells what kind off engine this is, we might be able to come up with a viable solution.

[DonTZ125]

The fact that you have a pulse at all from the coil suggests that it COULD be used; the question becomes 1) how to condition it so as not to fry the MS, and 2) how precise / repeatable is it.

[old guy]

The fact that you have a pulse at all from the coil suggests that it COULD be used; the question becomes 1) how to condition it so as not to fry the MS, and 2) how precise / repeatable is it.

Let me clear this up. If this is the type of module that he has there is only one electrical connection on this module and this is the kill button connection. There is no pulse on this wire. It just shorts the coil to kill the engine.As I said before this is not a cdi,it is a magneto that uses a solid state device instead of a set of point to trigger the circuit.
When it comes right down to it, this is kind of a wasted discussion because the OP has never responded to what type of unit this is, so we are really just guessing

[H2active]

Been out of pocket
This is a Briggs and scrap iron engine module. The wire is the kill wire, take it to ground and the engine dies.
On the reed switch front 60 hz required for 3600 RPM is no problem for a reed switch as most literature I find says 200 Hz is a good test frequency to determine point bouce time and this keeps things simple IF I dont get 2 pulses because of the 2 magnets. Current poll says it should act like one magnetic exposure.

Project
This is a test engine for direct (in the cylinder) injection hydrogen. I have built an injection port spark plug, got a clean air 300 psi gaseous injector with all the filters, regulators and such. I am now working on the control part. Thus the MS2 build and eventual installation.

I'm a mechanical guy that is trying to cross over to the dark side of electronics.
I built a kit car, ultralight airplane, dome house and many other weird stuff over the years, hydrogen is my current learning curve.

[old guy]

Does your application require you to control the ignition with the MS. If it doesn't I would just use the stock ignition module and either use a hall sensor on the flywheel or an inductive pickup off the plug wire to get your tach signal for MS.
I would still shy away from a reed switch because it is mechanical and therefore more prone to failure than a hall sensor which has no moving parts. Whichever you choose you are still going to have to fabricate some kind of adjustable bracket so you can set the timing.
Probably the best product for your application would be the Microsquirt. which is small and weather proof or the Microsquirt module if you are planning on embedding it in your product.

[H2active]

Does your application require you to control the ignition with the MS. If it doesn't I would just use the stock ignition module and either use a hall sensor on the flywheel or an inductive pickup off the plug wire to get your tach signal for MS.

Yes - H2 burns up to 10 times faster that gasoline. You pretty much have to play around TDC. The MS2 gives me that capability.

I would still shy away from a reed switch because it is mechanical and therefore more prone to failure than a hall sensor which has no moving parts. Whichever you choose you are still going to have to fabricate some kind of adjustable bracket so you can set the timing.

The literature I have from Digikey say the MTBF (mean time between failure) for reed switches approaches the life of hall effect solid state units. google hall effect vs. reed switches they have a comparision. As I understand it the MS2 has the capability to change the timing and also has a offset feature to compenstate for where ever you put the timing event. I "just" have to get the swich in the magnetic field and determine how many degrees from TDC it is and put that offset in. That why I got this unit instead of the miscro squirt.

Let the adventure continue.

[trakkies]

All I would add is I've never seen a reed switch used as a trigger on any electronic ignition system - even the earliest ones. When they actually operate is very hit or miss with field strength, compared to hall effect.

[H2active]

I'm sure there is a reason reed switches are not used, being stuborn to a fault is sometimes one of my features. I 'm looking for a hall effect switch for plan b, I'm wrong a lot but I learn alot.

See my post regarding injection determination questions on the Briggs 10hp -Hall Effect ignition trigger thread its old and I don't really expect a reply, but you got to try.
I guess my next task is to find, build a way to time the injection to the intake stroke instead of the a randon walk of either the intake or power stroke.

Thanks good posting here

[old guy]

Does your application require you to control the ignition with the MS. If it doesn't I would just use the stock ignition module and either use a hall sensor on the flywheel or an inductive pickup off the plug wire to get your tach signal for MS.

Yes - H2 burns up to 10 times faster that gasoline. You pretty much have to play around TDC. The MS2 gives me that capability.

I would still shy away from a reed switch because it is mechanical and therefore more prone to failure than a hall sensor which has no moving parts. Whichever you choose you are still going to have to fabricate some kind of adjustable bracket so you can set the timing.

The literature I have from Digikey say the MTBF (mean time between failure) for reed switches approaches the life of hall effect solid state units. google hall effect vs. reed switches they have a comparision. As I understand it the MS2 has the capability to change the timing and also has a offset feature to compenstate for where ever you put the timing event. I "just" have to get the swich in the magnetic field and determine how many degrees from TDC it is and put that offset in. That why I got this unit instead of the miscro squirt.

Let the adventure continue.

The Microsquirt is an MS2 in just a little different form factor.
As far as the reed switch, you can do what you choose, but I don't think you will be able to maintain any kind of steady timing.
Another thing to consider is that a B&S engine vibrates like a paint mixer. What do you think that is going to do to the reed switch?
As Trakkies said that is probably why you never see them used in an ignition system.

[trakkies]

I'm sure there is a reason reed switches are not used, being stuborn to a fault is sometimes one of my features. I 'm looking for a hall effect switch for plan b, I'm wrong a lot but I learn alot.

See my post regarding injection determination questions on the Briggs 10hp -Hall Effect ignition trigger thread its old and I don't really expect a reply, but you got to try.
I guess my next task is to find, build a way to time the injection to the intake stroke instead of the a randon walk of either the intake or power stroke.

Thanks good posting here

You obviously need a cam sensor if you want a pulse on the firing stoke. If this isn't accurate enough you could use it to mask the unwanted ones from a crank sensor.

[H2active]

Cam sensor would solve the problem. Now you can get one injection pulse every 720 degrees crank tied to the intake stroke. This is the same problem the guy had on this thread

3.5hp Briggs and Stratton

Mr old guy is there a conversion to tag on to the camshaft with a sensor of some kind of a one cylinder briggs and stratton or kohler engine?

I'll be OP for a while, sometimes making a living gets in the way living.
Thanks