yeah, i used weatherpak connectors on several circuits under the hood including the injectors and ignition to make sure i didn't have moisture or corrosion related electrical issues. on the previous wiring iteration running batch fire injection, i used the 3 position weatherpak connectors looking ahead towards the sequential wiring to make the change over easier.
as to the hall effect sensors for the new design, i spec'd a 13/16th" barrel type that's compatible with any ferrous metal toothed wheel. it doesn't have to see a magnet per se, it can discriminate the presence of a ferrous metal tooth if it's moving and change it's electrical state going high to low - high in a gap, low on a tooth. the same barrel type hall effect sensor also changes state when it detects the south pole of a magnet. the magnetic trigger doesn't require as small of an air gap. when it's triggered by a ferrous metal tooth, the air gap is more critical.
in part, that's why i moved the trigger wheel to the rear side of the accessory pulley, to improve run out on the teeth as they spin. the id of the trigger wheel has been machined to a very tight concentric fit to the od of the pulley's hub which maintains concentricity on the trigger wheel. there's only a couple thousandths run out at the od of the teeth - well within the .010" permissable wobble.
the new hall effect sensors aren't as cheap (by a factor of more than 10) as the flat pack type i used on the first rendition but they're going to be much easier to use than the variable reluctance sensor from an electrical/ electronic standpoint. i spent more time trying to dial in the v/r signal on the first version than i thought i should have. i farted around with polarity, sensitivity, and hysteresis trying to get a suitable trigger signal, and i don't like engineering that is that finicky.
another gripe i have with the v/r sensor is that the faster the crank spins, the larger the signal amplitude gets. the signal is in the mud at idle, at a half volt, and around 70 volts at 7000 rpm. the signal response from the hall effect device is constant at 12 volts up to 19,500 rpm from it's output lead. then the 12 volts is used to fire an led in an optoisloator package which in turn switches on a phototransistor with it's biasing set to fire a 5 volt trigger signal suitable for the megasquirt's microprocessor. the processor always sees a solid 5 volt trigger no matter what the rotational speed is and all of the signal conditioning is taken care of automatically between the hall effect device and the optoisolator. no fiddledy farting around trying to dial it in.
my next megasquirt build is going to be streamlined, modular, and slick. now that i have a handle on what the control and wiring set should be, it'll be much neater. i'll build the fet coil ignitors into the ms case along with the fet injector drivers, pare down the number of separate gauges by integrating oil pressure and temperature into the megasquirt, and using the megasquirt's pid boost controller. i will also start out building the megasquirt with a better handle on which components i can delete from the board during assembly.
there's a heck of a learning curve but the megasquirt is a true hobbyist's delight. it is so feature rich that you need to have a game plan together before you ever heat up a soldering iron. i have a way better handle on what i need from the ms now (and what i don't need.)
Login
Register
Gallery
FAQ
Search
how did you find my turbo3 project on the internet?
version 1.0 seems to work okay but the new design will allow for adjusting the air gap between the magnet and the pickup. it will be more industrial looking with not so much effort to keep things small.