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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Wed, 4 Oct 2000 13:09:29 GMT
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Viewed:
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629 times
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Hi Juergen,
> 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. I guess this is on purpose, so kids don't stick a bunch of battery
packs together to get a high voltage.
> 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.
So it should be no problem to tell them apart. But, it gets even better! I
connected a light sensor to the same port (which really just measures
resistance). The light sensor will read a dark value of about 400, and a light
value of about 800. This is using a thrd light actually used as a light
pointed directly at the light sensor to give more consistent readings. Also,
on a side note, I put a 1 by 2 beam with a hole in it directly in front of the
light sensor. This is similar to blinders on a horse. The sensor sees only
what is directly infront of it, and is much less succeptible to misreadings
caused by shadows and lighting in the room. I am really quite happy with the
setup.
> Your idea is both simple and great and I just wonder why
> nobody thought of it before. So how to get more lights?
> I just have one from the Ultimate Accessory Set.
You could order the lights from Lego Dacta, like I did (Actually I ordered
them from Spectrum, which is the Canadian version, and just down the road from
my house :) ) But the educational version of Lego is usually way over priced.
I think a better route would be to order the lights from Lego Shop at home. I
think they have the exact same type of lights as accessories for the trains.
They are much cheaper than from Dacta. Anyway, keep on building,
Rob
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Message has 1 Reply:
 | | Re: A neat idea for touch sensors
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| Hi Rob, (...) Yes. But by looking carefully at the connectors it's not too hard to figure out how to do it. (...) 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 (...) (24 years ago, 5-Oct-00, to lugnet.robotics)
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Message is in Reply To:
| | Re: A neat idea for touch sensors
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| (...) There are the Cybermaster touch sensors with resistors, but that's a rather expensive solution. (...) Your idea is both simple and great and I just wonder why nobody thought of it before. So how to get more lights? I just have one from the (...) (24 years ago, 4-Oct-00, to lugnet.robotics)
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