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DPRG: IR Sensor Workshop Revision
Subject: DPRG: IR Sensor Workshop Revision
From: Robert L. Jordan
rljordan at airmail.net
Date: Sun Feb 6 10:02:49 CST 2000
IR friends,
The circuit I shared with you for the IR Sensor Workshop,
Feb 5, has a flaw. This schematic to make an IR circuit to
run 38Khz IR and detect it can be found--
at http://www.stampsinclass.com/
goto download
pick 1.1 MB (71 pages)
Here is a revision to the final schematic in the Robotics!
book that will
make it work right. Also, there are some notes.
If you have already built the breadboard layout as shown
on the parts placement diagram (Fig. 4.3) and can't get
proper
operation, be aware there is a wiring error in that
diagrams.
The schematic (Fig. 4.4) is correct.
In the parts placement diagram, remove
the jumper from P4 to line 6 of the board, and its extension
>from line 6 to line 12. The little rascal runs very nicely
with
its IR "eyes" and even better with the subsumption program
now offered in the free downloads at parallaxinc.com under
the stamps in class, downloads section.
The Parallax Robotics! text shows two schematics,
one using a 0.1 and one using a 0.01 cap.
Craig and Ed Koffman recommended the use of a 0.1
capacitor and the 1 K pot to get the 38000 - 38 Khz
IR frequency needed.
Notes:
1. This circuit could easily be used stand alone for IR
detection. You will want access to an oscope
or to a Basic Stamp 2 to set the frequency of the
555 for the 38Khz frequency. Once done, the
circuit works nicely for IR reflection.
2. You can run several IREDS (IR LEDS) off of
the 555 output and have one detector for each.
That way you could detect in 2 or 3
direcitons at once.
3. Cover the IR LEDs with heat shrink to keep
the IR "light" out of the sensors. You only want
the IR energy coming out of the end of the IR
and heatshrink.
4. IR LED.
Any 920 nm IRED (IR LED)
Some are brighter than others.
6. IR 38Khz detector
Panasoninc 4602 from Digikey is good
Regards
Robert L. Jordan
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