Author Topic: Searching for photo transistor with optic fiber receptor  (Read 678 times)

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Offline TrickyNekroTopic starter

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Searching for photo transistor with optic fiber receptor
« on: June 16, 2012, 01:37:00 AM »
Hello guys!


Itīs really been a long time since I wrote in this forum last time, but I came to a point that I need your help.
I have been working on a university project that requires me to read an analog sensor and sent the data over
the can bus. Fortunately that part is over by now and I need to focus on building a PCB that actually has a small part of
the sensor.

The sensor consists of a foamy pad and two optic fibers, one for sending light to the sensor and the other for
receiving the portion of the light reflected inside the sensor. The amount of the light received back depends on the
pressure on the sensor but thatīs not important right now.

What I am asking for is an analog photo transistor that comes with a casing where I hook up the optic fiber.
The thing I really really need is a casing that comes or can accept a phototransistor.
Of course, I need also a casing that can accept a led or comes with a led for the other end/optic fiber.

I am not sure about the light absorption properties of this foamy material, but right now we are using wave lengths
in the red spectrum (from a led).
Thatīs why I would prefer a casing that doesnīt come with an embedded transistor. But anything is welcomed.

I also havenīt measured yet the diameter of the fiber but it should be less than 1mm, perhaps half or 3/4mm...
But thatīs not important right now, what is important though is to find a manufacturer that produces such casings.
Important note, due to the nature of the sensor, the optic fibers can not be changed.

Also for the first time, I really donīt care about the money... University pays, but we need something that we can find.
Farnell preferably, Mouser or Digikey available...

Thank you for your time!
Best Regards,

Lefteris, Greece (now in Germany... ;D )
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline Soeren

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Re: Searching for photo transistor with optic fiber receptor
« Reply #1 on: June 23, 2012, 03:10:42 PM »
Hi,

Thatīs why I would prefer a casing that doesnīt come with an embedded transistor. But anything is welcomed.
Your best bet is probably to make the housings yourself, that way you can tailor them to fiber as well as LED/phototransistor.
A 3D printer would make it extremely easy, but something like the smallest LEGO bricks would be another possibility.
Line the material with eg. tin foil if needed.


Also for the first time, I really donīt care about the money... University pays, [...]
Must be the German uni?  :P ;D
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline TrickyNekroTopic starter

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Re: Searching for photo transistor with optic fiber receptor
« Reply #2 on: June 25, 2012, 09:31:44 AM »
Hallo! Wie gehtīs? Itīs been some time since I last wrote here ;-)

Thatīs why I would prefer a casing that doesnīt come with an embedded transistor. But anything is welcomed.
Your best bet is probably to make the housings yourself, that way you can tailor them to fiber as well as LED/phototransistor.
A 3D printer would make it extremely easy, but something like the smallest LEGO bricks would be another possibility.
Line the material with eg. tin foil if needed.

Thatīs pretty much what the other guy did. He just used hot silicon glue to do the fiber LED binding but I tend not to
like it very much.
The output swing of one sensor is from 0.3V to 1.4V or something close and for the other pad,
the output swing is from 0.8V to 2.1V and thatīs not good.
Of course I can do software compensation but Iīm losing one the ADC resolution. And the whole thing
is based on an industrial application, so I need to find a sturdy viable, easy to use solution. But even if it
was for me, I would get it this way no matter what. Itīs optics, some degrees error can ruin your day, and
I really donīt want this on the final result.

I am thinking of using something like these, havenīt found the right one just yet but I think Iīm on the right track:
Hell it doesnīt allow me to post the Farnell link, I donīt know why...
But anyhow I was searching at the Fiber Optics category of Farnell, they have many things there that
may suit my needs.  8)

Also for the first time, I really donīt care about the money... University pays, [...]
Must be the German uni?  :P ;D

Cut poor Greece some slack  :P Itīs not that bad after all, but still yes, Iīm here in Germany,
actually in Bremen doing my Diplomarbeit at the Uni. And believe me itīs one of the best
choices I ever made. The only thing that really bothers me is the weather. Apart from that,
everythingīs more than fine! The bad thing is that Iīm here as an Erasmus student and that
means only one semester. But Iīll try to come back for master and perhaps PhD, I donīt
know yet. It depends on many factors. But yes, apart from having a large budget here, they
also know very well what risk capital is, and I really made some use of it already! :P
« Last Edit: June 25, 2012, 09:38:43 AM by TrickyNekro »
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

 


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