Subject:
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Re: 3-wire converter for homebrew sensors
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 26 Mar 1999 03:00:13 GMT
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Original-From:
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Pete Sevcik <sevcik@^ihatespam^flash.net>
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Viewed:
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1166 times
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Dennis,
Thanks for your encouragement.
The angle sensor connected straight to the RCX is non-linear because it is in
series with another resistor located inside the RCX.
During a sense operation, the RCX drives the sensor input from a 10K resistor to +5
volts. Call this resistor R1. The Sensor is a resistor between the input and
ground. (Call it R2). By Ohms law, the voltage across R2 is 5(R2)/(R1+R2). R1 is
a constant, and the voltage aproaches 5 as R2 becomes very large compared to R1.
I wonder if a log tapered pot (audio taper) would correct this problem ?
- pete.
Dennis Clark wrote:
>
> though. Pete, cool idea! However, why would your angle sensor be non-
> linear if connected directly to the RCX? It need not go through any diode
> path at all as its a direct connection. Just wondering.
>
> DLC
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
--
Pete Sevcik sevcik@flash.net
Techno-stuff Robotics
http://www.flash.net/~sevcik/
Robotics for FUN !
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message is in Reply To:
 | | Re: 3-wire converter for homebrew sensors
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| (...) [snip] (...) Ahh, but the stipulated purpose for Pete's sensor brick is that it gives a _linear_ response that isn't corrupted by the non-linear diode drop caused by currents that are often less than 2ma and perhaps not past the "knee" region (...) (25 years ago, 25-Mar-99, to lugnet.robotics)
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