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Andy Neil
12/16/05 09:40
Read: 667 times
Basingstoke
Uk


 
#105395 - basic Ohm's law
Responding to: Suresh R's previous message
Suresh R said:
Iam confused in selecting the rating of these components.can any one suggest me the required rating that must be used for these components to give a 15 V i/p to 7805..

It's basic Ohm's law: V=IR

You know the voltage you need to drop; you know the current (thought you didn't state it in your post) - hence you can get the required resistance.

The required power rating of the resistor is P=IV.

You need to think about how you will dissipate all that power without overheating the resistor or any other parts of your system...!

Although it's all possible, that doesn't necessary make it a good idea...

List of 33 messages in thread
TopicAuthorDate
Add on card programming      Suresh R      12/07/05 03:11      
   please clarify      Jan Waclawek      12/07/05 03:35      
      RE: please clarify      Suresh R      12/07/05 04:35      
         (E)ISA addressing      Jan Waclawek      12/07/05 04:48      
            IOW and IOR      Suresh R      12/08/05 04:52      
               not explicitly      Jan Waclawek      12/08/05 06:02      
                  IRQ in EISA slot      Suresh R      12/09/05 01:05      
                     interrupt      Jan Waclawek      12/09/05 02:21      
                        QBASIC programming      Valentin Angelovski      12/09/05 04:53      
                           reply      Suresh R      12/10/05 04:10      
                              DIP Switch Address Setting in EISA card      Suresh R      12/12/05 03:10      
                                 DIP switches...      Valentin Angelovski      12/12/05 03:55      
                                    card design enclosed      Suresh R      12/13/05 02:10      
                                       comparator      Jan Waclawek      12/13/05 02:30      
                           QBASIC live and well.      Charles Bannister      12/12/05 11:12      
                              NT - not quite      Andy Neil      12/12/05 16:16      
                                 timing in Win?      Jan Waclawek      12/12/05 16:21      
                              QBasic Lives!!!      Valentin Angelovski      12/12/05 17:24      
   refer to 'Barry B Brey'      Abhishek Singh      12/07/05 07:39      
   EISA Bus interfacing      Valentin Angelovski      12/08/05 15:54      
      beware if (E)ISA bus books      Erik Malund      12/09/05 08:11      
   Try this?      Andy Neil      12/14/05 15:16      
      Power resistor selection      Suresh R      12/16/05 04:52      
         dont do it      Erik Malund      12/16/05 06:39      
            LM317 is an option      Abhishek Singh      12/16/05 07:46      
               Wasteful!      Andy Neil      12/16/05 09:34      
                  if op can...........      Abhishek Singh      12/17/05 07:16      
                     Power!      Andy Neil      12/17/05 08:27      
         basic Ohm's law      Andy Neil      12/16/05 09:40      
            Trouble shoot      Suresh R      12/19/05 05:13      
               heating      Terry Lingle      12/19/05 07:08      
                  Reply : Heating      Suresh R      12/20/05 04:29      
                     if you refer to D4 then      Erik Malund      12/20/05 06:12      

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