rajbuddy007
Posts: 53
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I want to detect a flash of small pcb chip

Tue May 14, 2019 2:09 pm

Hello,
I want to detect a flash of small pcb chip for that i want to use photodiode with rapsberry pi. Please suggest me what to do.


Here's the diode i am using

https://www.digikey.de/product-detail/d ... R5EALw_wcB

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omegaman477
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Re: I want to detect a flash of small pcb chip

Tue May 14, 2019 6:03 pm

rajbuddy007 wrote:
Tue May 14, 2019 2:09 pm
Hello,
I want to detect a flash of small pcb chip for that i want to use photodiode with rapsberry pi. Please suggest me what to do.


Here's the diode i am using

https://www.digikey.de/product-detail/d ... R5EALw_wcB
Can you explain 'flash of small pcb chip' Do you mean a flash of light from a LED chip on a pcb? Or do you mean a spark from a failing IC?

That photodiode would be fine, but its sensitive to the yellow/green spectrum around 565nm. You need to ensure the photodiode is sensitive to the colour of the
flash'
..the only thing worse than a stupid question is a question not asked.

rajbuddy007
Posts: 53
Joined: Fri Apr 05, 2019 3:03 pm

Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 7:34 am

yes i meant the flash of red light from pcb. Just tell me how to make a circuit which is readable with gpio pins

Brandon92
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Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 7:53 am

rajbuddy007 wrote:
Wed May 15, 2019 7:34 am
Just tell me how to make a circuit which is readable with gpio pins
Are you paying us for the advice we give you?
Anyway, connect that photodiode to a opamp (to convert current of the photodiode into voltage). And the output of the opamp to a comparator to make it digital for the Rpi.

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mahjongg
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Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 9:30 am


LTolledo
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Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 10:10 am

Brandon92 wrote:
Wed May 15, 2019 7:53 am
rajbuddy007 wrote:
Wed May 15, 2019 7:34 am
Just tell me how to make a circuit which is readable with gpio pins
Are you paying us for the advice we give you?
You noticed that too?
Lately there's some kind of influx of these types of rash " new members" that seem to just demand we give solutions(s) for their RPI problems. :x
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

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Burngate
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Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 10:43 am

Or maybe they're just not very good at writing English, or expressing their wishes coherently and politely.

I can read "Just tell me how to ..." as an abrupt demand, or as a plea for simplicity - many of us here are very good at waffling, but less good at the clear guidance required. Me included, which is why I wouldn't make a decent teacher.

Brandon92
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Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 10:44 am

LTolledo wrote:
Wed May 15, 2019 10:10 am
You noticed that too?
Lately there's some kind of influx of these types of rash " new members" that seem to just demand we give solutions(s) for their RPI problems. :x
Indeed. But they don't realize that the response from the other members will not be "that" detailed at all (like I did) or they even don't replay to it at all.

edit:
Burngate wrote:
Wed May 15, 2019 10:43 am
Or maybe they're just not very good at writing English, or expressing their wishes coherently and politely.

I can read "Just tell me how to ..." as an abrupt demand, or as a plea for simplicity - many of us here are very good at waffling, but less good at the clear guidance required. Me included, which is why I wouldn't make a decent teacher.
You have also a good statement as well. So maybe is indeed a good idea to take those answers with a grain of salt.

rajbuddy007
Posts: 53
Joined: Fri Apr 05, 2019 3:03 pm

Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 12:16 pm

I am sorry I should have been more polite. I was in my deadline so trying to wrap up everything as fast as I could. Thanks for the responses so far and I would be grateful if you people guide me in solving my problems. All the members here, who found that statement inappropriate kindly accept my apology.

Brandon92
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Location: Netherlands

Re: I want to detect a flash of small pcb chip

Wed May 15, 2019 12:58 pm

What is by the way the duration of that small flash. If it is to "small" you could extend it with a (7)555 timer IC.

Are you looking for a finished product are can you use a breadboard with some chips on it.

rajbuddy007
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Re: I want to detect a flash of small pcb chip

Thu May 16, 2019 8:37 am

No It is like i am testing on a finished product so basically it has a small status led (very small red led) which blinks in an interval of time. So i want something which can detect that status light of that product and can be readable by PI. What will you suggest? A photodiode would be better or should i go for an LDR? I hope you got an idea.

Brandon92
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Location: Netherlands

Re: I want to detect a flash of small pcb chip

Thu May 16, 2019 9:56 am

I assume you have the pcb in a test fixture (see the pictures here) or something like this. In that case you would have 4 options I would think:
  • You can use the photodiode, but this require "more" hardware and possible a little bit of fine tuning.
  • You could use a LDR. Then you only need a comparator and some resistors (a opamp would also work).
  • If you have some test points, you could measure the voltage across the led during the test. If the led is good, the forwards voltage is according to the datasheet and if not the supply voltage is pressend.
  • A other option would be this. Someone is already testing the pcb. And that person could check if that led is blinking.
I hope this will give you some information.

rajbuddy007
Posts: 53
Joined: Fri Apr 05, 2019 3:03 pm

Re: I want to detect a flash of small pcb chip

Thu May 16, 2019 12:31 pm

Brandon92 wrote:
Thu May 16, 2019 9:56 am
I assume you have the pcb in a test fixture (see the pictures here) or something like this. In that case you would have 4 options I would think:
  • You can use the photodiode, but this require "more" hardware and possible a little bit of fine tuning.
  • You could use a LDR. Then you only need a comparator and some resistors (a opamp would also work).
  • If you have some test points, you could measure the voltage across the led during the test. If the led is good, the forwards voltage is according to the datasheet and if not the supply voltage is pressend.
  • A other option would be this. Someone is already testing the pcb. And that person could check if that led is blinking.
I hope this will give you some information.

Thanks for the reply. Its a SMD Chip LED smaller than a raspberry pi power led. Check out the link. Basically I have got the task to detect the LED blink. The LED blinks in variations (from 1 time to 4 times). So my task is whenever the led blinks the sensor should reflect it in python. Its like a automation test setup.

I am thinking to use LDR as its more convenient. The setup will be placed in a dark box and when the led blinks he ldr should sense and check how many times it blinked.

https://www.mouser.de/ProductDetail/Bro ... eViNSNPQ==

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