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???
02/08/08 08:38
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 		 #150458 - First things first - Begin at the beginning
Responding to: ???'s previous message
Shakir F.m said:
When i check the supply voltage on the oscilloscope (across vcc and ground) there is a lot of noise.

What, exactly, do you mean by, "a lot"?

shouldn't it be a straight 5V DC

yes, it should - and if it isn't, you have a fundamental problem!

There is no point in going any further with test programs or anything else until you have a good, clean, stable power supply!

i wrote a simple program to test the board...

Pointless!
There is no point in writing any software before the basic hardware (including the power supply) is working correctly!


the output is quite noisy..its not a clean square wave.

Is that suprising, given a noisy power supply?!


List of 58 messages in thread
TopicAuthorDate
problems with edge triggering and noise            01/01/70 00:00      
   5v regulator,capacitors - elko and creamic            01/01/70 00:00      
      not likely            01/01/70 00:00      
         not true!            01/01/70 00:00      
   How much noise?            01/01/70 00:00      
      using a 78L05 voltage regulator IC with 220 uF cap            01/01/70 00:00      
         be conservative ... for now ...            01/01/70 00:00      
   First things first - Begin at the beginning            01/01/70 00:00      
      yes i agree..            01/01/70 00:00      
         photo            01/01/70 00:00      
            Well done            01/01/70 00:00      
               the "backside" :)            01/01/70 00:00      
                  Use Solder Wick as Braid            01/01/70 00:00      
                     is this ok?            01/01/70 00:00      
                        i found this strange looking woven wire?            01/01/70 00:00      
                  Perf Board Types            01/01/70 00:00      
                  Pad-Per-Hole PTH            01/01/70 00:00      
                     How much ?            01/01/70 00:00      
                        This Much            01/01/70 00:00      
                           other boards            01/01/70 00:00      
                     Here\'s what I prefer.            01/01/70 00:00      
            it looks quite acceptable, with caveats ...            01/01/70 00:00      
      How much noise!            01/01/70 00:00      
   Regulator problems..            01/01/70 00:00      
      sorry wrong measurements            01/01/70 00:00      
         Actuall, you were right, in part ...            01/01/70 00:00      
            Different caps..            01/01/70 00:00      
      one more issue            01/01/70 00:00      
         7805            01/01/70 00:00      
            Swop the pins around !!            01/01/70 00:00      
            agreed            01/01/70 00:00      
               what about switching noise and ripple?            01/01/70 00:00      
                  to RE            01/01/70 00:00      
                     This is a real disappointment            01/01/70 00:00      
                        numbers            01/01/70 00:00      
                           that's not what was asked ...            01/01/70 00:00      
                              yes and no            01/01/70 00:00      
                                 I've got lots of those ...            01/01/70 00:00      
                                    not mostly - only and who cares            01/01/70 00:00      
                                       It's what's before the filter that matters!            01/01/70 00:00      
                                          enough            01/01/70 00:00      
                                             not exactly ...            01/01/70 00:00      
                                                as stated before            01/01/70 00:00      
                                                   Nonsense!            01/01/70 00:00      
                                                      you can't stop, can you            01/01/70 00:00      
                                                         I love to see Erik backpedal            01/01/70 00:00      
                                                            Better start giving a hoot            01/01/70 00:00      
                                                               as stated so often, I DO give a hoot ...            01/01/70 00:00      
                                                                  as stated so often, I DO give a hoot ...            01/01/70 00:00      
                                                                     I think you are right            01/01/70 00:00      
                                                                        I too favour looking inside black boxes            01/01/70 00:00      
                                                                           blindly?            01/01/70 00:00      
                                                                              Erik ... you\'re headed for a disappointment            01/01/70 00:00      
                                                                                 If you accept datasheet blindly I cant help            01/01/70 00:00      
                                                                                    you do not get the point, do you?            01/01/70 00:00      
                                                                     not exactly            01/01/70 00:00      
                                                                        I never made any such claim            01/01/70 00:00      
         gee ... that's a negative regulator ...            01/01/70 00:00      

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