[TriEmbed] TriEmbed Digest, Vol 39, Issue 18
Chip McClelland
chip at mcclellands.org
Wed Aug 24 20:32:37 CDT 2016
Robert and all,
So, here is what I am thinking, please let me know if there is a better way.
1) Transmitter - use a LMC555 timer to deliver 10 , 1uSec pulses a second in Astable mode. The data sheet <http://www.ti.com/lit/ds/symlink/lmc555.pdf> for the LMC555 timer says it can handle . This circuit will be turned on and off by the Arduino but that is all no PWM or triggering required. It will drive a 100mA 850nm emitter <http://www.marktechopto.com/pdf/products/datasheet/MTPS8085P_2015-05-07.pdf> with a very focused beam.
2) Receiver - I will use a matched 850nm phototransistor <http://www.vishay.com/docs/81527/bpw77n.pdf> wired as a common emitter amplifier. That way, the received pulse will cause the interrupt pin to go LOW and wake the Arduino.
3) Software, I will create a simple interrupt service routine that will register a pulse and determine how many if any pulses have been missed. I can use a running average smoothing function to get rid of noise so I don’t count a falling leaf.
I hope I am not missing something. Is there a better way to do this? Will I run into issues with changing ambient light or rain / snow causing problems? Will see but any heads up are appreciated.
Thanks,
Chip
> On Aug 24, 2016, at 10:00 AM, triembed-request at triembed.org wrote:
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> 1. Re: TriEmbed Digest, Vol 39, Issue 16 (Robert Gasiorowski)
>
>
> ----------------------------------------------------------------------
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> Message: 1
> Date: Tue, 23 Aug 2016 16:16:57 -0400
> From: Robert Gasiorowski <rgresume at gmail.com>
> To: Chip McClelland <chip at mcclellands.org>
> Cc: "triembed at triembed.org" <triembed at triembed.org>
> Subject: Re: [TriEmbed] TriEmbed Digest, Vol 39, Issue 16
> Message-ID:
> <CAEU50hUQ+S3f4_KTHTAXRCEmMx_tGiuGeb1k61Wq1atiCf12dw at mail.gmail.com>
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>
> If you decide to use 38kHz carrier, you will either use a lot of energy or
> limit your distance.
> Here's my suggestion:
> 1. set IR LED's current to 100mA or higher (up to 1A,)
> 2. send 1us-5us pulses, 10 to 50 per second,
> 3. use pin interrupt and timer to detect and count missing pulses
> 4. use lens (LED) and IR filter (detector)
>
> 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.
>
> On Tue, Aug 23, 2016 at 1:23 PM, Chip McClelland via TriEmbed <
> triembed at triembed.org> wrote:
>
>> 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.
>>
>> 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 (!?).
>>
>> Thanks, chip
>>
>> On Tuesday, August 23, 2016, <triembed-request at triembed.org> wrote:
>>
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>>> 1. Re: TriEmbed Digest, Vol 39, Issue 15 (Alex Davis)
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>>> ----------------------------------------------------------------------
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>>> Message: 1
>>> Date: Mon, 22 Aug 2016 13:28:21 -0400
>>> From: Alex Davis <alexd at matrixwide.com>
>>> To: triembed at triembed.org
>>> Subject: Re: [TriEmbed] TriEmbed Digest, Vol 39, Issue 15
>>> Message-ID:
>>> <1471886901.1337427.702662641.4268E605 at webmail.
>>> messagingengine.com>
>>> Content-Type: text/plain; charset="ISO-8859-1"
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>>>
>>>> All, any ideas on a low power (5mA and 3.3-5V) IR beam sensor
>>>> (transmitter
>>>> and reflector) I could use in an outdoor setting? Need to count
>>>> pedestrians walking on a gravel road and the width - 30' - is too great
>>>> for
>>>> ultrasonic. Ideally, could buy the sensor components directly and
>>>> integrate
>>>> them with my data logger board.
>>>
>>> Chip,
>>>
>>> looks like this one (https://www.sparkfun.com/products/11724) can be had
>>> in a 10-meter version, and uses 2.9 mA average, so maybe ultrasonic
>>> would work.
>>>
>>> I think decent-range beam-break is going to take some decent current.
>>>
>>> Alex
>>>
>>> --
>>> "The theater of noise is proof of our potential."
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>>
>>
>> --
>> Sent from my iPhone - please excuse the typos
>>
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