Subject:
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RE: Help with connecting pyroelectric sensor
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 7 Sep 1999 17:57:35 GMT
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Original-From:
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Tripp,Edwin <TRIPP@nomorespamOCLC.ORG>
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Viewed:
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445 times
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Gentlemen
The spec sheet for the part indicates that the 2.5 volt
reference is an *output* for reference purposes only.
The maximum load is 20 microamps. In other words, that
pin should only be tied to a high impedance input on a
voltage comparator or op amp used to detect the state
of the main output on pin 2. Also, the allowed load
on the output can be no lower than 125 Kohm. In other
words, an op amp is a necessity for MindStorms use.
Edwin Tripp
tripp@oclc.org
-----Original Message-----
From: Michael Gasperi [mailto:gasperi@alynk.com]
Sent: Tuesday, September 07, 1999 9:42 AM
To: lego-robotics@crynwr.com
Subject: Re: Help with connecting pyroelectric sensor
<lego-robotics@crynwr.com> wrote in message
news:84e2ed7a.25059866@aol.com...
> Which interface should I use, the one with, or without the op amp? How do • I
> connect the reference voltage to the interface?
>
> When looking at the interface with the op amp, I am assuming that I can
> attach two voltage regulators to the +7V lead--one at +5V for V+, and one • at
> +2.5V for the reference. However, the output from the sensor would be a • max
> of 5V, and I don't know how to find the proper value of R1 to show the
> correct sensor range from 0 to 5 volts.
You need at least part of the circuit with the opamp. All the diodes, C1
and R1. I doubt you need a +5v regulator for the supply, but you need a
2.5v reference. Maybe you can just use a resistor divider for that. I
can't tell how much ouput the thing makes, so you may need the opamp.
Normally R1 is a 1K. BTW the block diagram for the part shows the reference
and output reversed.
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | Re: Help with connecting pyroelectric sensor
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| Tripp,Edwin <lego-robotics@crynwr.com> wrote in message news:72B89459DD2BD21...clc.org... (...) Looks like it pays to read the instructions and not just look at the pictures. My guess is that the output sits at about 2.5v and moves up and down with (...) (25 years ago, 8-Sep-99, to lugnet.robotics)
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