ignition Kill for quickshift

[Guest]

Hello, I am working on a quickshift controller and am wondering which wire going to the coils I need to manipulate. Is it the 12v power wire that drives the coilthat needs to be interrupted to cause the coils not to fire? would this momentarily cut spark until 12v is applied again? also is there a delay while the magnetic field builds around the coil similar to a capacitor?

[posplayr]

Hello, I am working on a quickshift controller and am wondering which wire going to the coils I need to manipulate. Is it the 12v power wire that drives the coilthat needs to be interrupted to cause the coils not to fire? would this momentarily cut spark until 12v is applied again? also is there a delay while the magnetic field builds around the coil similar to a capacitor?

you could interrupt either. or you could interrupt the pickup as well.

Not sure what you plan on interrupting with or what but the coil negative gets some pretty big voltages on it.? The plus not so much. The pickup is pretty hefty as well.

[ashdricky]

you could interrupt either. or you could interrupt the pickup as well.

Not sure what you plan on interrupting with or what but the coil negative gets some pretty big voltages on it.? The plus not so much. The pickup is pretty hefty as well.

ok so the 12v + is at around what amps? I will likey be using an optoisolator for it's quick switching I need to be sure I wont melt the traces on the board

[posplayr]

ok so the 12v + is at around what amps? I will likey be using an optoisolator for it's quick switching I need to be sure I wont melt the traces on the board

The primary average current is about 3 amps with some AC and peaks to about 4 amps.

[ashdricky]

I was just checking out your solid state power box, very nice. would you recomend using an optoisolator to interrupt the ignition or is there a better device that you know of?

[posplayr]

I was just checking out your solid state power box, very nice. would you recomend using an optoisolator to interrupt the ignition or is there a better device that you know of?

A 12v nc relay on the ignitor ground would probably be safest. Not sure how fast you are trying to switch. Same thing would work on ignitor power.

[ashdricky]

the kill time is meant to be adjustable but could be as short as 20ms

[posplayr]

the kill time is meant to be adjustable but could be as short as 20ms

At 10K RPM 4Cyl wasted spark will fire a coil each 3 msec. I have not looked up specs, but mechanical is probably not going to be particularly reliable especially with bounce.

I'm not sure what ignition you are planning but most aftermarket have an immobilize, or alternatively they will probably stop firing if either +12V or ground is interrupted (neither of these should carry much current or have high voltage transients on them). Either of these electrical paths would be easier to open and close than anything else available external to the ignition.

I know you are still looking for me to confirm an opto isolator, but I have no idea what you would do with it or what circuit you would presumable switch with it or what specific part you think you would want to get. So sorry can't give a technical assessment on a "notion".

[ashdricky]

At 10K RPM 4Cyl wasted spark will fire a coil each 3 msec. I have not looked up specs, but mechanical is probably not going to be particularly reliable especially with bounce.

I'm not sure what ignition you are planning but most aftermarket have an immobilize, or alternatively they will probably stop firing if either +12V or ground is interrupted (neither of these should carry much current or have high voltage transients on them). Either of these electrical paths would be easier to open and close than anything else available external to the ignition.

I know you are still looking for me to confirm an opto isolator, but I have no idea what you would do with it or what circuit you would presumable switch with it or what specific part you think you would want to get. So sorry can't give a technical assessment on a "notion".

I am running a standard dyna 2000 from dynatek which dose have a side stand interrupt which can also act as an ignition retard input which is why I need to build a stand alone system so I could potentially activate the ignition retard when nitrous is used. I am designing the board for the quickshift governor myself and would like it to be standalone not needing to piggyback off of another controller. as far as the optoisolator goes I am thinking that I might be able to get one with a high switching speed from digikey or mouser

[ashdricky]

it looks like I may be able to find a Solid State relay, as I understand this is a more robust option than an optoisolator.

[posplayr]

it looks like I may be able to find a Solid State relay, as I understand this is a more robust option than an optoisolator.

The opto isolator isolates the drive circuitry from the load circuitry. That doesn't mean the Drive circuitry can handle the load. In fact many can not depending on what you are trying to do.

Yes a SS relay will typically handle much more current and voltage. but if you try to put one of them in series with the coil you will reduce the voltage to the coil, they are typically pretty high resistance.

Unless it is an Opt SS relay, you could still drive the SS relay with the op-to relay to get your isolation.

You need to know what you are trying to open/close, then find a part suited to the job. The device has to be sized to where you plan to put it.

[ashdricky]

The opto isolator isolates the drive circuitry from the load circuitry. That doesn't mean the Drive circuitry can handle the load. In fact many can not depending on what you are trying to do.

Yes a SS relay will typically handle much more current and voltage. but if you try to put one of them in series with the coil you will reduce the voltage to the coil, they are typically pretty high resistance.

Unless it is an Opt SS relay, you could still drive the SS relay with the op-to relay to get your isolation.

You need to know what you are trying to open/close, then find a part suited to the job. The device has to be sized to where you plan to put it.

I plan on controlling the +12v wire to the coils themselves and ideally I can find a component that can be soldered to the PC board. I am a bit confused by Opt SS relay vs op-to relay vs SS relay?

[ashdricky]

would something like this fit the bill?

http://www.digikey.com/Web%20Export/Supplier%20Content/Clare_212/PDF/Clare_SolidState.pdf?redirected=1

probably a foolish question but other than our stators all our electrics are DC correct?

[ashdricky]

when you mention relays having high resistance through the circuit we want to control what are we considering to be high resistance? This opto relay has 8 Milli ohms of resistance if I am reading the data sheet correctly. since this relay has a normally open circuit, I am thinking to make it turn on as soon as the key is turned and control that controlling circuit with a small high speed optoisolator

[posplayr]

when you mention relays having high resistance through the circuit we want to control what are we considering to be high resistance? This opto relay has 8 Milli ohms of resistance if I am reading the data sheet correctly. since this relay has a normally open circuit, I am thinking to make it turn on as soon as the key is turned and control that controlling circuit with a small high speed optoisolator

I believe my reference to "relatively high resistance" was in the context of a solid state relay. 8 milli Ohms seems very low and more like a mechanical relay.

I have recently looked at various FET,Solids State relays and Opto switches and don't remember anything with that low of resistance on the output side at least that and that would carny any significant current (5+ amps).

You can compare the resistance of various component yourself if you go to Digikey and do searches through the various component types.

A MOSFET is typically in the 0.1-0.15 ohm range and the comparable SSR's I was looking at were much higher. For what I was looking for and the price point I was trying to get they tended to be higher. Looking again there is quite a range depending upon the various options there are to choose from, so you could be able to find something with that low of resistance if the other parameters suit your needs.




SS relay is higher than that.