Speed input maximum frequency

dstevens
Posts: 11
Joined: Wed Jul 18, 2007 9:03 pm

Speed input maximum frequency

Postby dstevens » Wed Sep 17, 2008 3:56 pm

Is there any way around the 2kHz maximum speed input frequency?

Using the ABS sensors we are currently exceeding this frequency. The ABS has 50 teeth, so provides 50 pulses per wheel revolution, so the datalogging limit is 40 revs/sec. The tire dynamic circumference is just over 2 metres, so this gives 80 m/s or 179 mph. For most cars this would not be a problem, but the top speed we've seen so far out of this car is just over 105 m/s (234 mph / 378 kph).

Otherwise I'm going to have to make a pulse divider for the wheel signals.

faraday
Posts: 267
Joined: Sun Feb 25, 2007 1:18 am

Postby faraday » Wed Sep 17, 2008 5:56 pm

:shock: What is this beast and where do you run it :?:

dstevens
Posts: 11
Joined: Wed Jul 18, 2007 9:03 pm

Postby dstevens » Thu Sep 18, 2008 5:00 am


Support

Postby Support » Fri Sep 19, 2008 5:32 pm

We have got some boards coming in which are programmable dividers, to give you a divide ratio of up to 256 from the input to output, that should be fast enough even if you make it to 10k rpm!!
Email me mhill at race-technology.com for more info.

Regards,
Martin

Turby
Posts: 296
Joined: Thu Nov 17, 2005 2:28 pm

Postby Turby » Mon Sep 22, 2008 1:09 pm

If you want a simple fixed divide by 2 (or 4) then have a look at

http://www.elecfree.com/electronic/circ ... vide-by-2/

and

http://komponenten.es.aau.dk/fileadmin/ ... 13.pdf.pdf

A bit of vero or matrix board and a chip, maybe come connectors and a few minutes soldering should have you sorted in no time.

HTH

dstevens
Posts: 11
Joined: Wed Jul 18, 2007 9:03 pm

Postby dstevens » Wed Sep 24, 2008 3:13 am

Thanks. I've already incorporated a division circuit into the output of the ABS interface circuit I use.


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