Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Need help : sunlight detector and flash detector circuits

Status
Not open for further replies.

yaya_sensei

Newbie level 2
Joined
Jul 5, 2007
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,295
sunlight detector

Hi,
Im a final year degree student in electrical and electronics. Im doing a project that has to do with detection of sunlight illumination and flash. Can you recommend sunlight detector and flash detector circuits that can easily be integrated with PIC16F877A?

Thank you
 

GrandAlf

Advanced Member level 2
Joined
Mar 9, 2002
Messages
520
Helped
47
Reputation
92
Reaction score
6
Trophy points
1,298
Location
UK
Activity points
4,730
sunlight detector

You would need photodiode for flash rather than photocell as it is much faster responding. Flash durations may be too short for any meaningful processing, you may need some sort of sample and hold circuit. Sunlight should not be a problem at all.
 

yaya_sensei

Newbie level 2
Joined
Jul 5, 2007
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,295
photodiode flash sensing diode

I did buy a PIN photodiode but I could not get the output. Probably the circuit Im using is not suitable for photodiode. Can you recommend any circuits that are using photodiode which can really produce outputs? I would really appreciate if you can give me schematics of the circuits.
 

artem

Advanced Member level 4
Joined
May 22, 2003
Messages
1,350
Helped
126
Reputation
252
Reaction score
32
Trophy points
1,328
Location
Turkey
Activity points
13,450
detector flashcan

The current of back biased diode depends on light energy coming to its sensing side. Also diode dark current will depend on temperature and varies a lot .
Trying to use same sensor for flash and sun illumination detection means at some extend the amplifier should support wide input current range from diode and be not excited at same time.

The flash can be detected by differentiating the photodiode amplifier output (simple rc circuit).
I would go with transimpedance amplifier (that depends on your strict requirements which you dont know yet) with low gain first and then additional amplifier for sun illumination level detection. Differentiate the output from first amplifier and detect it with threshold tune comparator.

Low gain transimpedance is needed to prevent amplifier from excitation when diode is maximum radiated under the sun , dark current (when exposed to highest possible temperature) is maximum and there will still be room for flash detection.

Pay attention to opamp offset vs temperature and photodiode current vs temperature .

What is the pin diode id you own? BPW34 is nice one for such things.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top