Hi Joe,
I'm a bit far away to help but I recommend you go look at the siliconchip website

Silicon Chip Electronics Magazine for Hobby Electronics, Computing, Kits and Projects.

Then go look for some of their vehicle projects, you will be able to view snippets of the articles and find which one would suit you and more than likely you can buy a kit and put it together yourself.

Go have a look and if you have any more question just sing out I'd be glad to assist.

Regards Bryan

i want $5000 for my idea!!! jk, butt it sounds like what you need is PWM controller (maybe, i'll probably get corrected on that)

i got your point, you need to alarm when df/dt is above a limit, for what you need alarm? for +ve or -ve gradiant?
you have to have a frequency to voltage convertor, trhen pass it through a capacitor and have to use one/ two comparators(slope detector) . for +ve rate of change and -ve rate of change. then combine both to get final alarm

told you i'd be corrected

The hardware is easy enough.
WHy give up on the code you have been writing in Yanka ?
Post the flow chart and tell us what you can not do with it etc.

I live in the Oklahoma panhandle.

What application do you need such a function for?
I am fairly familiar with the GM HEI systems but I cant come up with a logical reason to need to know how fast an engine changes speed?
Over rev protection is logical and commonly used but I have not seen a need for rate of change protection or indication?

There are frequency to voltage converter IC's like the LM2907 that can put out a simple voltage reference in relation to the input frequency and with some basic comparators an simple circuits an all analog device can be fashioned that would give a output for an excessive increase or decrease of RPM's.

In case an output shaft broke wouldn't the engine over rev so fast it would blow before the rpm limit kicked in? Being able to measure the rise in RPM would all you to stop the engine before it even reached it's high RPM limit if the RPM rise was too fast, kind of like short circuit protection on power supplies which measure dI/dT

In case an output shaft broke wouldn't the engine over rev so fast it would blow before the rpm limit kicked in? Being able to measure the rise in RPM would all you to stop the engine before it even reached it's high RPM limit if the RPM rise was too fast, kind of like short circuit protection on power supplies which measure dI/dT

In every application I have ever seen the over rev function is what keeps things from flying apart. You dont set the rev limit above the engines designed maximum RPM.

I have a MSD ignition system on my old Ford 460 engine that has a built in rev limiter I have set at 5000 RPM although the engine itself is capable of holding together to well over 5500.

When you kill the ignition that generally tends to stop all RPM increases instantly anyway.

tcmtech something bothers me about that, if the rotor shaft is accelerating fast enough inertia should keep it going up briefly you can't instantly stop acceleration instantly there has to be some kind of overshoot possibility.

Ahh, tcm, it suddenly dawned on me cause I'm slow to remember these things sometimes.
It's called inertial moment, it's how flywheels allow a buffering of energy. Ever seen what happens when a heavy fly wheel is stopped instantly? Generally things tend to explode =) Granted you obviously haven't had problems with it and it may not even be applicible to the original poster, depends entirly on the mass and how fast things are spinning to see if it'd be a problem. But if the load to a motor is suddenly cut and the engine starts accelerating even once the energy supply to that engine is cut it will still have inertial mass that will keep it accelerating. Engine compression will slow it down and it really depends on how fast the engine is accelerating when it his the RPM cutoff as to what'll happen.

It's kind of like what happens when there's enough joule energy in the wire when a breaker trips, the device will fry anyways.