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by rajbuddy007
Wed Jun 12, 2019 11:17 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

Thanks for all the help. I checked my photo-transistor response to that SMD led and based on that i changed the sleep time of the code and final its detecting. Thanks for all the help people. Much appreciated ;) ;)
by rajbuddy007
Tue Jun 11, 2019 1:01 pm
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

Sorry for all the misunderstanding. My colleague has interchanged the transistor. Moreover, I just connected the circuit as shown and is working fine for the flash of my phone (giving desired 3.3V) but when i tested it with the subject (SMD LED) its not responding. What should be my next step?? SMD ...
by rajbuddy007
Tue Jun 11, 2019 10:15 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

Please see the image. I dont know why i am not getting enough voltage. If i am exposing it to very bright phone led flashlight then only it is giving max 800mV. I built the circuit which was given above, Not able to find out where am i going wrong

https://imgur.com/a/JcznGAo
by rajbuddy007
Thu Jun 06, 2019 2:30 pm
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

PiGraham wrote:
Thu Jun 06, 2019 1:33 pm
rajbuddy007 wrote:
Thu Jun 06, 2019 12:43 pm

I have tried the cicrcuit with 100K resistor and exposing it to the camera flashlight but it is giving max 400mV.
So it is definitely responding to light level then?
Yes it is responding to light level but not to that smd led from the chip.
by rajbuddy007
Thu Jun 06, 2019 12:43 pm
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

The spec says Collector light current 200uA at 5V and 200lx illuminance, 70uA at 20 lx so you could expect 200uA in a bright daylit room, maybe <=100uA in the dark room in your photo. https://en.wikipedia.org/wiki/Illuminance#Common_illuminance_levels So connected as pcmanbob's circuit with a 10k p...
by rajbuddy007
Thu Jun 06, 2019 12:14 pm
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

Data for the LED shows luminous intensity of 110mcd This calculator shows an illuminance of 27500lx at 2mm using 0.110 candela and 0.002m and 1100lx at 10mm if we just assume an isotropic radiation pattern. So you should have planty of light from the LED to operate the sensor if you aim them right ...
by rajbuddy007
Thu Jun 06, 2019 11:46 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

The spec says Collector light current 200uA at 5V and 200lx illuminance, 70uA at 20 lx so you could expect 200uA in a bright daylit room, maybe <=100uA in the dark room in your photo. https://en.wikipedia.org/wiki/Illuminance#Common_illuminance_levels So connected as pcmanbob's circuit with a 10k p...
by rajbuddy007
Thu Jun 06, 2019 11:42 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

pcmanbob wrote:
Thu Jun 06, 2019 10:04 am
Are you just trying to use the LED to turn the transistor on ?

if so read the data sheet about sensitivity area on page 4

https://www.mouser.co.uk/datasheet/2/42 ... 244748.pdf
No i placesd just to see how it is reacting to it.
by rajbuddy007
Thu Jun 06, 2019 9:55 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

pcmanbob wrote:
Thu Jun 06, 2019 9:45 am
If you illuminate it enough it should give you 3.3v on the emitter.

are you sure you have the circuit connected correctly ?

may be post some pictures so we can see how its connected.

just upload them to imgur.com and post links her.

Please check the url https://imgur.com/a/0VZiSEK
by rajbuddy007
Thu Jun 06, 2019 9:47 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

If you illuminate it enough it should give you 3.3v on the emitter. are you sure you have the circuit connected correctly ? may be post some pictures so we can see how its connected. just upload them to imgur.com and post links her. No its not giving infact i have placed a red led very close to it....
by rajbuddy007
Thu Jun 06, 2019 9:26 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

Have you got the transistor connected the right way round ? The shorter leg is the collector ( C ) The transistor is listed as an ambient light sensor so it will be triggered by the day light, what happens if you cover the transistor to prevent any light reaching it ? My bad i interchanged the circ...
by rajbuddy007
Thu Jun 06, 2019 8:55 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

The connection of an npn photo transistor to the gpio is the same as a normal npn transistor, you just don't have to worry about the base leg. you would connect it to the gpio like this https://i.imgur.com/hdomVrD.jpg and you could see if its detecting anything with a very simple program like this ...
by rajbuddy007
Thu Jun 06, 2019 7:30 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

Thanks a lot for the help guys. Much appreciated.
by rajbuddy007
Wed Jun 05, 2019 7:47 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

A digital light detector would save you a lot of work. For example, https://www.adafruit.com/product/4162 https://cdn-learn.adafruit.com/assets/assets/000/073/757/small240/adafruit_products_VEML7700TopHeader.jpg On the other hand if you want to learn about phototransistors, here are a couple of use...
by rajbuddy007
Tue Jun 04, 2019 9:49 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

Re: light detector with photo transistor

Thank for the reply.
I want to detect a light from this LED. Please do check and tell me what should be the best practice for it?

https://www.mouser.de/datasheet/2/216/A ... 102303.pdf
by rajbuddy007
Tue Jun 04, 2019 7:31 am
Forum: General discussion
Topic: light detector with photo transistor
Replies: 33
Views: 1033

light detector with photo transistor

Hello, I want to detect a red light from SMD Red LED with the help of photo transistor. I know the fact that in order to make it readable by Rpi i have to connect it to comparator. It would be nice if anybody help me with making a circuit with it. Phototransistor: https://www.mouser.de/ProductDetail...
by rajbuddy007
Fri May 24, 2019 2:09 pm
Forum: General discussion
Topic: Coding mechanical button presser - how to fix my code?
Replies: 5
Views: 215

Re: regarding code

I do have the code but i dont know how to modify it as per my requirements. In that code it is pressing the button simultaneously as per the code writte. I want my code to be user input. For ex If i run the code it should ask which function you have to run and if i put 1 press) then the code should ...
by rajbuddy007
Fri May 24, 2019 1:26 pm
Forum: General discussion
Topic: Coding mechanical button presser - how to fix my code?
Replies: 5
Views: 215

Re: regarding code

Thanks for the reply but I already have my code. I just need to call various function by just manually giving the user input and then it calls that particular function. Could you help me with that?
by rajbuddy007
Fri May 24, 2019 12:55 pm
Forum: General discussion
Topic: Coding mechanical button presser - how to fix my code?
Replies: 5
Views: 215

Coding mechanical button presser - how to fix my code?

Hello Guys, I have made a mechanical button presser circuit with stepper motor. I am so beginner in programming. My task is to press the button in different interval of time. So i need to write a code in which if we run it will ask the predefined function (ex Long press, 8 sec press, 2 sec press). H...
by rajbuddy007
Thu May 16, 2019 12:31 pm
Forum: Automation, sensing and robotics
Topic: I want to detect a flash of small pcb chip
Replies: 12
Views: 633

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

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 compara...
by rajbuddy007
Thu May 16, 2019 8:40 am
Forum: General discussion
Topic: RPi for button presser
Replies: 19
Views: 606

Re: RPi for button presser

hello guys,

New update in this. O have changed my mosfet with logic level mosfet. The circuit got worked. But the solenoid heated up so badly. What should i do to my circuit if want to give 12V external supply?
by rajbuddy007
Thu May 16, 2019 8:37 am
Forum: Automation, sensing and robotics
Topic: I want to detect a flash of small pcb chip
Replies: 12
Views: 633

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

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 s...
by rajbuddy007
Wed May 15, 2019 12:16 pm
Forum: Automation, sensing and robotics
Topic: I want to detect a flash of small pcb chip
Replies: 12
Views: 633

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

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 apo...
by rajbuddy007
Wed May 15, 2019 7:34 am
Forum: Automation, sensing and robotics
Topic: I want to detect a flash of small pcb chip
Replies: 12
Views: 633

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

yes i meant the flash of red light from pcb. Just tell me how to make a circuit which is readable with gpio pins
by rajbuddy007
Tue May 14, 2019 2:09 pm
Forum: Automation, sensing and robotics
Topic: I want to detect a flash of small pcb chip
Replies: 12
Views: 633

I want to detect a flash of small pcb chip

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/de/vishay-semiconductor-opto-division/BPW21R/751-1013-ND/1681147?utm_adgroup=Optical+Sensors&mkwid=sq...

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