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   sci.electronics.basics      Elementary questions about electronics      72,318 messages   

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   Message 71,139 of 72,318   
   Look165 to All   
   Re: Resistance Light and Dark Values   
   15 May 19 20:23:37   
   
   From: look165@numericable.fr   
      
   A bad friend which act only in one way !   
      
   Phil Hobbs a écrit le 15/05/2019 à 20:05 :   
   > On 5/15/19 1:26 PM, Look165 wrote:   
   >> For an alarm, do you care to 10ms for instance ?   
   >>   
   >> Phil Hobbs a écrit le 15/05/2019 à 19:20 :   
   >>> On 5/15/19 1:14 PM, Look165 wrote:   
   >>>> Yes, it can.   
   >>>> A photodiode takes time to turn on or off, about the same a LDR takes.   
   >>>> LDR are reversible, standard photodiodes are only one way.   
   >>>>   
   >>>> Cursitor Doom a écrit le 15/05/2019 à 16:30 :   
   >>>>> On Wed, 15 May 2019 11:15:18 +0200, Look165 wrote:   
   >>>>>   
   >>>>>> A LDR reacts in some ms when the light's  wavelength is in the   
   >>>>>> operating   
   >>>>>> range.   
   >>>>> You really can't beat a photodiode, though.   
   >>>>>   
   >>>>>   
   >>>>>   
   >>>>>   
   >>>>>   
   >>> A fast photodiode will respond in picoseconds.  Even slow ones are in   
   >>> the tens-of-nanosecond range if used with the right transimpedance amp.   
   >>>   
   >>> They're also highly linear and stable, neither of which is true of CdS   
   >>> cells.   
   >>>   
   >>> Cheers   
   >>>   
   >>> Phil Hobbs   
   >>>   
   > Of course not, but you gave Bad Info about photodiodes, who are sort of   
   > friends of mine. ;)   
   >   
   > Cheers   
   >   
   > Phil Hobbs   
   >   
      
   --- SoupGate-Win32 v1.05   
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