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07/21/04 16:47
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 		 #74624 - Relay interface problem
I have read

http://www.8052.com/forum/read.phtml?id=64374

I am having problems with relay.
When I switch on the circuit OR reset the micro the relay switches ON and since I write 00H to that port after bootup the relay turns off.

I am using 6V cube type relay , with a free heeling diode .

I have pulled up P3.0 with 1K resistor
Base of the 547 is connected to P3.0 through 22K resistor
One end of relay coil to 5V
Collector toother leg of relay coil
Emitter to GND

Sorry I am not good at electronics, I would like to know how to decide the resistor values, for proper biasing ..& also how to solve this problem and it's cause.

Also since I would like to to operate 6 relays in future should I use ULN2003

Thank you
Deepak


List of 50 messages in thread
TopicAuthorDate
Relay interface problem            01/01/70 00:00      
   RE: Relay interface problem            01/01/70 00:00      
   RE: Relay interface problem            01/01/70 00:00      
      RE: Relay interface problem - Mikkel            01/01/70 00:00      
   RE: Relay interface problem            01/01/70 00:00      
      RE: Relay interface problem            01/01/70 00:00      
      Relay interface problem -looking at it            01/01/70 00:00      
      Ic / Ib = 10...20            01/01/70 00:00      
         RE: Ic / Ib = 10...20 - Kai            01/01/70 00:00      
      RE: Small Addition to the above post            01/01/70 00:00      
   RE: Relay interface problem            01/01/70 00:00      
   RE: Relay interface problem            01/01/70 00:00      
   Negative Logic...            01/01/70 00:00      
      RE: Negative Logic...            01/01/70 00:00      
         What I am doing            01/01/70 00:00      
            RE: What I am doing            01/01/70 00:00      
            RE: What I am doing            01/01/70 00:00      
               RE: What I am doing            01/01/70 00:00      
      will my 89c51 reset ?            01/01/70 00:00      
         RE: will my 89c51 reset ?            01/01/70 00:00      
         RE: will my 89c51 reset ?            01/01/70 00:00      
            RE: will my 89c51 reset ?            01/01/70 00:00      
               RE: will my 89c51 reset ?            01/01/70 00:00      
                  RE: will my 89c51 reset ?            01/01/70 00:00      
                     What's wrong NOW            01/01/70 00:00      
                        RE: What's wrong NOW            01/01/70 00:00      
                        RE: What\\\'s wrong NOW            01/01/70 00:00      
                           RE: Corrected Top Link            01/01/70 00:00      
                           What's wrong 2            01/01/70 00:00      
                              RE: What's wrong 2            01/01/70 00:00      
                                 RE: What's wrong 2            01/01/70 00:00      
                        RE: What's wrong NOW            01/01/70 00:00      
                           RE: What's wrong NOW            01/01/70 00:00      
            RE: will my 89c51 reset ?            01/01/70 00:00      
               RE: will my 89c51 reset ?            01/01/70 00:00      
                  Forget reset 1st connect relay            01/01/70 00:00      
                  RE: will my 89c51 reset ?            01/01/70 00:00      
   Interface works Now            01/01/70 00:00      
      RE: Interface works Now            01/01/70 00:00      
         RE: Interface works Now            01/01/70 00:00      
            RE: Interface works Now            01/01/70 00:00      
               RE: Interface works Now            01/01/70 00:00      
               RE: Interface works Now            01/01/70 00:00      
                  RE: Interface works Now            01/01/70 00:00      
   Problem 2            01/01/70 00:00      
   RE: Relay interface problem            01/01/70 00:00      
      RE: Relay interface problem            01/01/70 00:00      
         RE: Relay interface problem            01/01/70 00:00      
   RE: Relay interface problem            01/01/70 00:00      
      interface problem2 solved            01/01/70 00:00      

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