Post by thread:[EE]: Photo Diode question

I need a larger detector area than a single photodiode. Is there any reason I shouldn't daisy-chain them together in series? Jay -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Jay Hanson wrote... >I need a larger detector area than a single photodiode. Is there any reason >I shouldn't daisy-chain them together in series? Put them in parallel, not series. Photodiodes deliver current proportional to the incident radiation; to get the effect of a larger area, the individual diodes would need to be in parallel so the currents add. DD -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> I need a larger detector area than a single photodiode. Is there any reason > I shouldn't daisy-chain them together in series? If any diode is dark, then it will block current in the whole chain. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, spam_OUTolinTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

You can also either use a lens to focus your light or get a bigger photodiode. At 03:20 PM 3/3/02 -0500, you wrote: > > I need a larger detector area than a single photodiode. Is there any >reason > > I shouldn't daisy-chain them together in series? > >If any diode is dark, then it will block current in the whole chain. > > >******************************************************************** >Olin Lathrop, embedded systems consultant in Littleton Massachusetts >(978) 742-9014, .....olinKILLspam@spam@embedinc.com, http://www.embedinc.com > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Tnx for the help guys. Jay -----Original Message----- From: pic microcontroller discussion list [PICLISTKILLspamMITVMA.MIT.EDU]On Behalf Of Mark Perri Sent: Sunday, March 03, 2002 2:30 PM To: .....PICLISTKILLspam.....MITVMA.MIT.EDU Subject: Re: [EE]: Photo Diode question You can also either use a lens to focus your light or get a bigger photodiode. At 03:20 PM 3/3/02 -0500, you wrote: {Quote hidden}> > I need a larger detector area than a single photodiode. Is there any >reason > > I shouldn't daisy-chain them together in series? > >If any diode is dark, then it will block current in the whole chain. > > >******************************************************************** >Olin Lathrop, embedded systems consultant in Littleton Massachusetts >(978) 742-9014, EraseMEolinspam_OUTTakeThisOuTembedinc.com, http://www.embedinc.com > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

EG&G makes (made?) a series of 4 quadrant photo diodes used for position detection. They have a large (2cm square) surface area. We have then in a system that images IR-LEDs for 3-D position sensing. There are a PITA to use because any spurious reflections in the work space result in a postition shift, so it is VERY clear that these devices are summing all input over the entire area. Mark Perri wrote: > > You can also either use a lens to focus your light or get a bigger photodiode. > > At 03:20 PM 3/3/02 -0500, you wrote: > > > I need a larger detector area than a single photodiode. Is there any > >reason > > > I shouldn't daisy-chain them together in series? > > > >If any diode is dark, then it will block current in the whole chain. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

>EG&G makes (made?) a series of 4 quadrant photo diodes used for position >detection. >They have a large (2cm square) surface area. We have then in a system that >images IR-LEDs for 3-D position sensing. There are a PITA to use because any >spurious reflections in the work space result in a postition shift, >so it is VERY clear that these devices are summing all input over the >entire area. I know what you mean. I am using them like PV cells (for voltage, not current). If I hook eight in series, I get over 3v under fluorescent lights. I believe most people use them differently. Jay -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads