Subject:
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Re: Chaining multiple RCX's output to input
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 27 Oct 1999 19:41:18 GMT
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Original-From:
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Stephen Unwin <stephen@elmsfarm.(nomorespam)demon.co.uk>
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Viewed:
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638 times
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On Wed 27 Oct, Michael Gasperi wrote:
>
> Eric Brok <brok@fcjsvc.hvu.nl> wrote in message
> news:FK9Lxs.49z@lugnet.com...
>
> > Another variety is using a motor as a sensor(!). It only takes a small
> > manual turn of a new Technic motor to make the RCX or Scout respond, for
> > example by driving another motor. Observaton: the sensing motor is much • more
> > sensitive in one direction than in the other.
>
> > Does anybody think doing this like this may harm the harware in the longer
> > run?
>
> Using a motor as a tachometer has come up before and I used to be worried
> about this causing damage. I have it from the LEGO engineers I met at
> mindfest that you can not hurt the RCX by hooking a motor to the input and
> spinning it at any kind of normal speed. There clearly is a limit to the
> voltage protection, but they wouldn't say what it was. The reason it
> appears to only work in one direction is the inputs only work with the
> voltage in one polarity. When you spin the motor in one direction it
> generates a positive voltage and negative when you spin it backwards. The
> RCX can't measure negative voltage.
>
>
Pop a 10K ohm resistor in series with the motor.
On my quick test with a variable resistor I got a value of 513 with the
resistor at 9.7k. With a 10k resistor, the RCX raw value is now
flickering between 510 and 511.
P.S. same with the older style motor
/////
< .. >
>
- stephen@elmsfarm.demon.co.uk
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Message has 1 Reply:
 | | Re: Chaining multiple RCX's output to input
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| Stephen Unwin <lego-robotics@crynwr.com> wrote in message news:Marcel-1.53-102...n.co.uk... (...) That makes sense cause the RCX has a 10K pulling the input up to 5V. The 10K you put in series with the motor will put the voltage at half way (2.5V) (...) (25 years ago, 27-Oct-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: Chaining multiple RCX's output to input
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| Eric Brok <brok@fcjsvc.hvu.nl> wrote in message news:FK9Lxs.49z@lugnet.com... (...) more (...) Using a motor as a tachometer has come up before and I used to be worried about this causing damage. I have it from the LEGO engineers I met at mindfest (...) (25 years ago, 27-Oct-99, to lugnet.robotics)
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