Subject:
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Re: is it possible to use a polarity switch with a RCX input?
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Newsgroups:
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lugnet.robotics, lugnet.robotics.rcx
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Date:
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Tue, 26 Mar 2002 13:16:11 GMT
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Viewed:
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1178 times
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"Jerry Kalpin" <jdkalpin@sympatico.ca> writes:
> In lugnet.robotics, Steven Nickle writes:
> > In lugnet.robotics, Jonathan Wilson writes:
> > > Basicly, what I want is a button, switch or whatever on my model that
> > > when moved one way causes one input to be sent to the RCX but when moved
> > > differently it causes a different input to be sent to the RCX. Should
> > > also have a 3rd "off" state.
> > > I am going to use it on my RCX controlled tank. RCX will use 2 touch
> > > sensors plus 1 motor to drive treads forward or back, touch sensors will
> > > trigger if it bumps into something.
> > > The "switch" I need will controll second motor attached to a large
> > > turntable to rotate turret.
> >
> > Use a resistor to make one of the states of the switch read less than a • full
> > short. Setup as a light sensor. 0 means off 50~ means one state and • 100
> > means another.
> >
> > This is the basis for alot of the touch sensor multipliers. I am sure if
> > you dig around you can find the right values. I don't have any my books • handy.
>
> But... be aware that the 'polarity switch' has only two connectors (for • two
> sets of wires). It's not a '3-way' where you can try to select one of two
> inputs by moving the lever. The action is forward-off-reverse with one
> power source connected to one motor.
I'm not very familiar with electronics, but I am wondering whether the
combination of two diodes with a resistor could solve the problem. I mean
this: when current flows in a certain direction, it crosses a diode,
resulting in a very low resistence. When the polarity is reversed, current
passes through the other diode (wired with opposed polarity), which is in
series with a resistor. If this works, the polarity switch can be used as a
three states input device for the RCX, which would be a nice application.
Talking about polarity switches, which IMO are very useful devices, I know
that they are unavailable at S@H if the destination is in the US, but I want
to point out that they are available for all the European countries. If you
need some of them, find a friend from UK or Germany willing to order and
re-ship them in the US.
I would offer to do that myself, but Italy's not yet been included in the
list of countries served by Lego Direct :-(
Ciao
Mario
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