Med/High Speed Switching

Discussion in 'Embedded Systems and Microcontrollers' started by Rickg5106, Nov 18, 2010.

  1. Rickg5106

    Thread Starter New Member

    Mar 1, 2010
    A thread was started in the Projects section of this site but this is a better spot for it.

    As a disclaimer/excuse, I am a mechanical guy and I want to do everything that way. I understand there are more cooler :cool: ways to do it, my thought default is mechanical.

    Another is I hate just buying stuff. I don't learn anything and I didn't increase my skill set by just throwing cash at something.

    Soooooooo Here is what I want to do and lets see what I can come up with.

    I have a motorcycle motor that has 2 hall effect switches that fire the cylinders in a round about way. It's an I4 and cylinders 1&3 and 2&4 are ganged so each fires twice per cycle and the gangs are 180 out of phase with each other.

    I want to be able to take the coil impulse and switch it to ground to shut the coil off as part as a RPM limit circuit but I want to be able to switch between the gangs so as not to load up one set of cylinders.

    This will happen as part of a Launch sequence so the motor will be up against this for 2 or 3 seconds at least and could be operating at up to 9000 motor rpm but I doubt it. So at that speed this would be switching a 18,000 cycles per minute,(Is that 300 Hz?).

    Can you give me a hint about what kind of Micro proccessor I should be looking at? I used to know basic and have a couple of reference books on the shelf. Looks like it's time to blow the dust off them.

    General consensus says the load from the coils @13 vdc is 4.6 amps.

    I think this will be controlled by an RPM switch, or write it into the code, watch the output from one of the Hall effect switches and use that signal to toggle a couple of MOSFET's in a pattern of On, Off, On, Off, Off. then loop back. The other coil will be phased 180 out or so.
    The reason for the double Off is I want the RPM limit to be a command as opposed to a suggestion.

    Any ideas?
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    It might be easier to try breaking or switching the Hall effect trigger, so the coil has no high power spark to get rid of.
  3. Rickg5106

    Thread Starter New Member

    Mar 1, 2010
    But I need to tap it AFTER I use it for the RPM switch and the tach otherwise everything dies. I can use it for signal, (reference), I think, but I don't think I can get away from switching the coil feeds.