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Sandip Basu
02/22/10 05:38
Modified:
  02/22/10 05:59
Read: 833 times
Kolkata (calcutta)
India


 		 #173409 - Zero crossing detector - technique adoption
So many articles are written on this topic, - new techniques are developing to detect the zero crossing as early as it occours.
As in PIC 12C508 and in AVR182 the high voltage live line can be connected through some megaohm resistor directly to the port pin of the micro. Some clamping diodes are there in-built. In AT89C51 or C52 there is no such clamping diode. Can I use such diodes externally if I want to connect high voltage live line through some megaohm resistor directly to the port pin and detect zero-crossing in the firmware. If it is possible then what type of diode should I use and what should be the maximum rating of the diode.

List of 25 messages in thread
TopicAuthorDate
Zero crossing detector - technique adoption      Sandip Basu      02/22/10 05:38      
   Sounds like a bad idea to me!      Andy Neil      02/22/10 06:06      
      relying on parasitic diodes      Erik Malund      02/22/10 07:49      
         Confusing      Sandip Basu      02/22/10 07:58      
            I mean      Erik Malund      02/22/10 08:03      
            Designing to typical values      Andy Neil      02/22/10 08:52      
               what blather      Erik Malund      02/22/10 09:07      
      " IDEA ? " - RIDICULOUS      Sandip Basu      02/22/10 07:54      
         at least for this one      Erik Malund      02/22/10 08:07      
         Oh dear:      Christoph Franck      02/22/10 08:13      
            tough, but true      Andy Neil      02/22/10 08:30      
            just caught this one      Erik Malund      02/22/10 08:35      
         Idiom      Andy Neil      02/22/10 08:25      
            It really is a *very* bad idea!      Andy Neil      02/22/10 08:46      
         Don't blindly follow app note      Oliver Sedlacek      02/22/10 08:39      
            It's not so much the parasitic diodes...      Andy Neil      02/22/10 08:49      
               two reasons      Erik Malund      02/22/10 08:51      
                  What should I do ...      Sandip Basu      02/22/10 11:32      
                     That won't help at all!      Andy Neil      02/22/10 11:40      
                     two wrongs      Erik Malund      02/22/10 12:23      
            Most app-notes don't work ... because they're wrong!      Richard Erlacher      02/22/10 17:29      
         This is typical ...      Richard Erlacher      02/22/10 17:26      
            I hate to tell this,...      Kai Klaas      02/22/10 19:32      
               App engineers not always the sharpest tools in the shed      Per Westermark      03/12/10 07:23      
   Unbelievable!!        Kai Klaas      02/22/10 17:12      

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