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WhiteWizzard
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Joined: 05/04/2013
Location: United Kingdom
Posts: 2794

Posted: 02:56pm 10 Feb 2015

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The board is just a suggestion for the chip part (if you're ok at SMD soldering then this could be small.

Also, you only need one to detect the 'colour' it can see, with data read being classified into red or green led (and it can adjust for daylight too to eliminate false detection).

It is rather code intensive, but is a neat solution. Alternative is a couple of LDRs on top of the two LEDs but they may give false reads at times.

If I think of anything else I will give a shout . . .

For everything Micromite visit micromite.org

Direct Email: whitewizzard@micromite.o

bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2870

Posted: 07:20pm 10 Feb 2015

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Bob,

A couple of these Photodiodes should do the trick

RS components want you to order in lots of 5 but they ship for free.. I believe that the diode will conduct when lit so glue them over the LEDs.

I would put a 4k7 ohm in series with the Anode and connect the other end of the resistor to 3v3 with the Cathode to GND. sense the junction with an IO pin.. If high LED is off if LOW LED is ON.

Of course you probably need to have a good read of the specs first, I have no actual experience with them myself..

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

BobD

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Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 08:43pm 10 Feb 2015

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Mick,
they look good except for two things. They aren't in stock. I haven't looked into that yet. The real question is red sensitivity. The data sheet specifies a range of 430 nm to 610 nm. I want it to detect red and green. According to what I read, 610 nm is at the orange end of the red range which is 610 to 760. If I knew the range of the emitter led I may be OK but I doubt that I can find that out.

RS don't seem to have any other suitable devices. I had a quick look at Element 14 but their terms and conditions seem draconian. Even if a problem is their fault it is your problem. I'm not sure I want to deal with them.

Phil
I'll now look at your suggestion in detail. I put it off in preference to a local solution.

Bob

bigmik

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Posted: 08:47pm 10 Feb 2015

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Hi Bob,

I only glanced at the data on that page but they quoted infra-red, ultra violet AND visible light range so I assumed they would be suitable for the entire visible light range.. as Infrared and UV are at opposite ends of the visible range.

They state stock will be in 3-March.. Not too bad seeing how long this thread has been going anyway is it? besides they should be available elsewhere..

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

bigmik

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Location: Australia
Posts: 2870

Posted: 08:52pm 10 Feb 2015

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Bob,

I did a bit of Dr Googling research and it seems that humans can only see in the range 390-70nm range and the spec of this transistor is 350-1100 so you should easilly be able to detect the red/green leds that are in your controller.

That only leaves the delay before shipping issue. (About 3 weeks)

Regards,

Mick

EDIT ***

Bob,

Here is a short list of alternatives that RS list of visible light photo-transistors.

List

Mick
Edited by bigmik 2015-02-12

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

BobD

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Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 09:06am 11 Feb 2015

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Thanks for the info Mick. I'm too busy to evaluate it right now but I'll get back.

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 5921

Posted: 11:48am 11 Feb 2015

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Do you want to take in to account a power failure?

If the power goes off will you be able to determine what state the door is in?

Around here the power goes of often so it's something I have to allow for.
My door controller is similar to yours (but B&D) and it has an annoying intermittent fault which also causes conditions the same as AC power failure.

I would stick to a couple of reed switches to indicate open and closed rather than take the info off the controller.

Jim

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bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2870

Posted: 12:16pm 11 Feb 2015

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bigmik said humans can only see in the range 390-70nm range

Oops!!! That should have been 390-700nm range Sorry about my FFS (Fat finger syndrome)

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

BobD

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Posts: 935

Posted: 12:19pm 11 Feb 2015

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If the power fails then the green (OPEN) light flashes very fast. Two quick presses of the operate button will then normalise the indications. I also intend to have a switch mounted on the concrete floor to indicate closed. The door controller gives such useful indications that I would like to use them.

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