Subject:
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Re: IR sensors
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 4 Aug 1999 00:12:21 GMT
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Original-From:
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Hidekazu Oki <hoki@princeton+AntiSpam+.edu>
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Viewed:
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2299 times
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To blink LEDs at 40khz, you could try using the 555 timer. Radio Shack
carries the 555 timer chip, a little booklet explaining how to
use it, and any external components you need.
In addition to the 555 chip, you'll just need three resistors and a
capacitor to drive that LED. (You will probably not need
an external transistor, the 555 chip can output 200mA or up to 600mA,
depending on whether or not it is a lower power version or not.)
One warning: You can operate the 555 chip at a variety of voltages, but
you should make sure not to exceed the recommended voltage and current
limit for the LED.
If V_in is the voltage you use to operate the 555 chip, you should wire
a resistor with resistance R_series in series with the LED before
connecting to the output of the 555 timer chip, given the LED's rated
voltage is V_led and rated current, I_LED:
R_series * I_LED + V_led = V_in
Solving for R_series:
R_series = (V_in - V_led ) / I_LED
If you'd like more detailed plans, I could scribble something up, but the
booklet is worth getting anyway, since you'll need to get the 555 chip and
a few components anyway.
I hope this is helpful..
-Hide
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Message is in Reply To:
 | | IR sensors
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| I have both a miniboard and a Handy board. I have recently purchased some Sharp 40mhz IR detectors to use with these boards. I have very little knowledge of electronics and don't know how to flash the IR LED at a rate that the detectors will need. (...) (26 years ago, 3-Aug-99, to lugnet.robotics.handyboard)
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