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Suresh R
07/18/06 22:55
Read: 1577 times
Chennai
India


 
#120541 - Choosing Bleeder resistor values
Responding to: Erik Malund's previous message
Erik Malund said:

1) 10K between B-E of BC556.
2) 1K2 between B-E of BC337.


If you do not include these 2, the circuit MAY work (I would not omit them). However, there often (especially at higher temps) is a little, tiny, minuscule current flowing even when everything is 'off'. These resistors avoid this mini-current creating 'accidents'


Ok. Thanks Erik. I would like to know how to choose those resistor(bleeder) values.


Suresh.



List of 49 messages in thread
TopicAuthorDate
Driving 12 Volts relay by 5 Volts microcontroller      Asok Sankar Rudra      07/17/06 18:04      
   12v relay      D.c. Van Warendorp      07/17/06 19:59      
      This will not work properly!      Kai Klaas      07/18/06 09:41      
         well, it might      Erik Malund      07/18/06 09:56      
         pullup?      Jan Waclawek      07/18/06 13:00      
            Doable, but disadvantagous      Kai Klaas      07/19/06 08:51      
               language and a comment      Erik Malund      07/19/06 08:58      
                  Makes only 3 drivers per port      Kai Klaas      07/19/06 09:44      
      12v relay      D.c. Van Warendorp      07/20/06 11:36      
   12V relay driver for 80C52        Kai Klaas      07/17/06 20:57      
      12V relay driver for 80C52      Asok Sankar Rudra      07/17/06 22:01      
      Analysis      Suresh R      07/18/06 12:34      
         sure.but why? this is \"grab bag values\"      Erik Malund      07/18/06 12:49      
            Re: Analysis      Suresh R      07/18/06 14:31      
               basically they are 'bleeders'      Erik Malund      07/18/06 14:35      
                  Choosing Bleeder resistor values      Suresh R      07/18/06 22:55      
                     Values Are design Specific      Abhishek Singh      07/19/06 00:45      
                        how to calculate?      Suresh R      07/19/06 02:37      
                           what you are missing is that a transistor junction      Erik Malund      07/19/06 06:50      
                           Two ways of calculation...        Kai Klaas      07/19/06 10:27      
                              Thank you very much!      Suresh R      07/19/06 12:41      
                                 Nearly....      Kai Klaas      07/19/06 12:51      
                                    BC556 base current direction...      Suresh R      07/19/06 14:39      
                                       Three currents arround the base...      Kai Klaas      07/19/06 22:24      
                                          Yes. Its clear for me now.      Suresh R      07/20/06 07:08      
                                             Was a pleasure...      Kai Klaas      07/20/06 10:27      
                                                So Nice of You. Thanks again!      Suresh R      07/20/06 11:29      
   Didn't search first      Andy Neil      07/17/06 23:27      
      Everything is already here. That is not the point!      Kai Klaas      07/18/06 08:17      
         Maybe it IS the point      Richard Erlacher      07/18/06 08:43      
            Please read again his post      Kai Klaas      07/18/06 09:09      
               He'd have seen other alternatives      Richard Erlacher      07/18/06 10:59      
                  I give up...      Kai Klaas      07/18/06 11:28      
                     don't      Erik Malund      07/18/06 11:48      
         faq      Jan Waclawek      07/18/06 13:14      
            Beat me to it      Jon Ledbetter      07/18/06 13:18      
            freewheling      Per Guldmann      07/18/06 14:09      
               1n4148      Jan Waclawek      07/18/06 16:23      
               Heaven, no!      Kai Klaas      07/19/06 08:17      
                  as usual, the global became specific      Erik Malund      07/19/06 08:36      
                     That's why I...      Kai Klaas      07/19/06 09:06      
                  FAQ update      Jan Waclawek      07/20/06 15:16      
                     Comment      Jon Ledbetter      07/20/06 15:32      
                        It's fixed now. Thanks.      Jan Waclawek      07/20/06 15:45      
   Alternatives      Sasha Jevtic      07/18/06 08:49      
   yet another way      Oleg Sergeev      07/19/06 00:24      
      Trouble making      Kai Klaas      07/19/06 09:09      
   the case of fault      Oleg Sergeev      07/19/06 05:31      
      Some thoughts      Kai Klaas      07/19/06 08:40      

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