Subject:
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Re: IR Transmit ?!? HELP
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 22 Apr 1998 04:28:00 GMT
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Original-From:
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Fred G. Martin <fredm@media.mit.edu*antispam*>
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Viewed:
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780 times
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> I recently assembled a Handy Board, everything is perfect except for the
> IR Transmitter. The IR Tx LED does not light. It is not the LED itself
> because I replaced it. I can't seem to figre out what's wrong. Please
> help.
Did you follow the instructions in the HB Assembly debug? at
http://el.www.media.mit.edu/projects/handy-board/hbassem/hbassem5.html
it says:
Output Stage
If LED9R fails to light after the poke command is issued, trace the
following progression of signals. Please refer to the infrared output
schematic:
* 6811 Timer Output 2. This is the signal from the 6811 that enables
the IR transmission circuit. Check pin 28 of the 6811; it should be
high. The signal is wired to pin 2 of U7; it also should be high.
* Oscillator Output. Look at the signal on pin 3U7; when the 6811
timer output 2 is high, it should be a 40 kHz square wave. If not,
check for proper installation of U7, R4, and C6.
* Inverter. The 40 kHz square wave should go to pin 1 of U9, where it
is inverted and output on pin 2 of the same chip.
* Transistor Drive. The 40 kHz signal then passes through R3, where it
is delivered to the base of Q1. Check for the signal's presence at
these points.
* Transistor and LED Wiring. Check that the emitter lead of the
transistor is properly grounded, and that LED9R and R5 have good
solder joints.
let us know the results.
fred
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Message is in Reply To:
 | | IR Transmit ?!? HELP
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| I recently assembled a Handy Board, everything is perfect except for the IR Transmitter. The IR Tx LED does not light. It is not the LED itself because I replaced it. I can't seem to figre out what's wrong. Please help. Thank You Peter Eacmen (27 years ago, 22-Apr-98, to lugnet.robotics.handyboard)
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