<div dir="ltr">If you decide to use 38kHz carrier, you will either use a lot of energy or limit your distance.<div>Here's my suggestion:</div><div>1. set IR LED's current to 100mA or higher (up to 1A,)</div><div>2. send 1us-5us pulses, 10 to 50 per second,</div><div>3. use pin interrupt and timer to detect and count missing pulses</div><div>4. use lens (LED) and IR filter (detector)</div><div><br></div><div>Alternatively, you could use short bursts of 38kHz carrier (also at higher current, but probably not as high as above.) This way, you could use one of Vishay's detectors, which usually come with IR filters.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Aug 23, 2016 at 1:23 PM, Chip McClelland via TriEmbed <span dir="ltr"><<a href="mailto:triembed@triembed.org" target="_blank">triembed@triembed.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Alex, yes, bought and tested that one. But humans are not reflective sir only about 12'. Cars to 30' easy so will eventually use it to replace the pneumatic tubes across the road. <div><br></div><div>Bought a matched pair of IR emitter and phototransistor yesterday. Will see if I can build my own circuit as this seems to be a new and novel application (!?). </div><div><br></div><div>Thanks, chip<span></span><br><br>On Tuesday, August 23, 2016, <<a href="mailto:triembed-request@triembed.org" target="_blank">triembed-request@triembed.org</a><wbr>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Send TriEmbed mailing list submissions to<br>
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1. Re: TriEmbed Digest, Vol 39, Issue 15 (Alex Davis)<br>
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Message: 1<br>
Date: Mon, 22 Aug 2016 13:28:21 -0400<br>
From: Alex Davis <<a>alexd@matrixwide.com</a>><br>
To: <a>triembed@triembed.org</a><br>
Subject: Re: [TriEmbed] TriEmbed Digest, Vol 39, Issue 15<br>
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> All, any ideas on a low power (5mA and 3.3-5V) IR beam sensor<br>
> (transmitter<br>
> and reflector) I could use in an outdoor setting? Need to count<br>
> pedestrians walking on a gravel road and the width - 30' - is too great<br>
> for<br>
> ultrasonic. Ideally, could buy the sensor components directly and<br>
> integrate<br>
> them with my data logger board.<br>
<br>
Chip,<br>
<br>
looks like this one (<a href="https://www.sparkfun.com/products/11724" target="_blank">https://www.sparkfun.com/prod<wbr>ucts/11724</a>) can be had<br>
in a 10-meter version, and uses 2.9 mA average, so maybe ultrasonic<br>
would work.<br>
<br>
I think decent-range beam-break is going to take some decent current.<br>
<br>
Alex<br>
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--<br>
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