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Tom Covo wrote in message ...
> Hi all,
>
> I would just like to pose a new idea. Current light bricks have lights, and
> different caps to provide different colors. What I am experimenting with • now
> is the use of Light Emmiting Diodes(LEDs).
> LEDs will only light up if the current is travelling in the right
> direction (polarity). So what I did was connect two LEDs, one green and one
> red, in different directions. What happens is this:
> The green LED lights up if one button is pressed, and the red one • lights
> up if the other one is pressed.
> But be careful if you are using the 9-volt power pack. you must use a
> resistor if you don't want to blow your LEDs. If you are using mindstorms,
> you could probably just lower the power level for that output.
The way the RCX controls power level, you would still need a resistor since
it is pulse width controlled, not voltage controlled.
This reminds me of the time in college we had to design our own project and
build it. I built a programable IC tester. Someone else was building
something with IR LEDs and sensors. When he tried his first pair he got no
response. I looked at his circuit and asked if he had a series resistor. He
said: "No." I told him to throw out the LED he was using and add a series
resistor to his circuit.
The neat thing was all the people connecting up ICs wrong provided some nice
bad ICs for my tester. Every once in a while you would hear a "POW!" from
one of the other benches.
Frank
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Message is in Reply To:
 | | Home-made Light Bricks
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| Hi all, I would just like to pose a new idea. Current light bricks have lights, and different caps to provide different colors. What I am experimenting with now is the use of Light Emmiting Diodes(LEDs). LEDs will only light up if the current is (...) (24 years ago, 26-Jan-00, to lugnet.dear-lego, lugnet.robotics)
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