Need Help!- Proximity switch and frequency

[woffler]

I am trying to use a NPN proximity switch 3 wire ,Dc volts ,10 to 24 volts ,NO closed to sense speed .However i have it working and it works fine at lower speeds and i use the Mach 3 spindle calibration tool , a scope tool the problem is at the lower end the two signals track fine as the speed increases, until mid range and then they start getting further apart instead of closer. I guess the question is this ! is this the result of the frequency of the proximity switch falling off ie ; being out of it's range , i have know info as to frequency of the existing switch i am wondering if a higher frequency switch could solve my problem. Any reply's would be greatly appreciated.

[Al_The_Man]

Many proximity's are limited in their frequency range, there is one that is made for this application, Honeywell Gear-Tooth sensor, 1GT101DC, it is used in automobiles for timing off the Camshaft or crankshaft. Used to be around $30.
If you have a auto wrecker near you, they can be salvaged quite cheaply.
What are the TWO signals you mention?
Al.

[brucemazor]

It kind of sounds to me your real issue might be in the prox's switching speed capabilities. If you are running at a high speed the switch might not be droppjng out by the time your pickup makes again. so it would be switching rate or frequency.

But then I could be wrong!!! have agood day