Software Dyno...

[Dave Zug]

> From:          "Rich Vandervoort" <richvandervoort at hotmail.com>

> Here's how we used to get wheels speeds from competitors ABS systems.  Tap 
> into the wheel speed signal at the ABS controller.  Note use twisted pair 
> wiring with a grounded shield, do not route near spark plug wires or similar 
> noise sources.  The consequence of noise on wheel speeds can be no brakes. 

UUH...OK that cans that idea for me. in fact heres an official "don't 
try this at home" stamp.  THUMP ;-) 
 
> Just use an off the shelf F to V converter (frequency to voltage) and feed 
> the resulting analog signal into something that can use to record the signal 
> versus time.  Calibrate a voltage to speed conversion using steady speed and 
> some reliable speed measurement device(speedo?).  Note use an undriven wheel 
> and the signal will be extremely accurate as there are usually something 
> like 50 teeth on a speed ring.  Note your wheel speed tap may put noise on 
> the speed signal if you do not match the polarity of the F to V and the ABS 
> controller.  Also the newer ABS systems have quite sophisticated wheel speed 
> diagnostic circuits and may disable ABS once the F to V is hooked up.  We 
> used to buffer the signal, but I am unsure of the circuitry.
> 
> 
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~~~
Dave Z. www.delanet.com/~tgp