Subject:
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Re: A neat idea for touch sensors
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 5 Oct 2000 11:53:20 GMT
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Viewed:
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477 times
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Hi Rob,
"Rob Stehlik" <Robbby31@hotmail.com> writes:
>
> > It seems that you are using two lamps where one should suffice,
> > with another short cable to make the proper connection.
>
> I realize that I am using two lights where I only need one.
> Its just simplest to connect both lights to one sensor. I think
> I came up with a scheme to use only one light, but the wiring
> was somewhat convaluted. (You want the light to be connected in
> series with the wire, not in parallel, otherwise it will try
> and light up from the small power supplied by the RCX to the
> sensor) The way lego has made their electrical connectors makes
> it difficult to connect things in series.
Yes. But by looking carefully at the connectors it's not too hard
to figure out how to do it.
> I guess this is on purpose, so kids don't stick a bunch of
> battery packs together to get a high voltage.
I think it is just that in most cases parallel connections are
needed, and you got to decide between the two possibilities
if you want to make things as easy as they are.
And there are older kids who do the high voltage thing anyway
(sorry, can't find the article now).
> > Also, if you multiplex this sensor with an ordinary one, you
> > won't be able to distinguish whether only the ordinary or both
> > sensors have been pressed, I suppose. Can you try that?
>
> Actually, in my setup, you can distinguish between the two sensors
> individually, and when both are pressed. When the (normal) sensor is pressed,
> I get a raw value of about 40. When the sensor with the resisitor is pressed,
> I get a value of about 50. When both are pressed, I get a value of about 20.
It seems that the resistance of the light is quite low,
about half the resistance of the sensors themselves.
This is because the switches in the touch sensors are not made from metal
but conductive rubber, which has a noticeable resistance.
I'll try something like that myself on the weekend.
BTW, the trick with the light sensor won't work with the
Cybermaster sensors, as their resistance is much higher
and you get raw values in the 500-800 range from them.
Jürgen
--
Jürgen Stuber <stuber@loria.fr>
http://www.loria.fr/~stuber/
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Message is in Reply To:
 | | Re: A neat idea for touch sensors
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| Hi Juergen, (...) I realize that I am using two lights where I only need one. Its just simplest to connect both lights to one sensor. I think I came up with a scheme to use only one light, but the wiring was somewhat convaluted. (You want the light (...) (24 years ago, 4-Oct-00, to lugnet.robotics)
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