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???
02/26/09 07:09
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Msg Score: -1
 -1 Answer is Wrong		 #162866 - As Aamir Javaid said about input to 8051.
Responding to: ???'s previous message
Aamir Javaid said:
This is another project other then that LED Display.
I want to give a sinusoidal input to 8051 but 8051 can only take input in square waveform (0-level & 1-level).for that purpose i was thinking of using a comparator. i have "lm339". can anyone help me with the circuit to attach it with 8051.range of input voltages is from 2-7Volts and reference voltage will be 4 or 5 volts.


Is the pin of MCU received >~5.5V-+7V????

Suggest to added two diodes like added picture from Kai.
For protection use.

www.shareapic.com/public/view/33741


Thank's
Jeckson Ben





List of 27 messages in thread
TopicAuthorDate
comparator with 8051            01/01/70 00:00      
   What have you tried?            01/01/70 00:00      
      description of project            01/01/70 00:00      
         Look at photo transistor            01/01/70 00:00      
            further description            01/01/70 00:00      
               But why 7V ?            01/01/70 00:00      
   Another project?!            01/01/70 00:00      
      this is another project            01/01/70 00:00      
   Not a sinusoidal waveform!            01/01/70 00:00      
      Well, it can look like a sine...            01/01/70 00:00      
         still problem with comparator            01/01/70 00:00      
            Circuit missing            01/01/70 00:00      
            sorry the circuit is here            01/01/70 00:00      
               the circuit            01/01/70 00:00      
                  Why bandages, and why 9V VCC?            01/01/70 00:00      
                  VREF is wrong!            01/01/70 00:00      
               How is Vref 4V ?            01/01/70 00:00      
            used two diodes at input to MCU            01/01/70 00:00      
               Doesn't solve the Vref problem!            01/01/70 00:00      
   kai, help me with comparator            01/01/70 00:00      
      Give this a try...            01/01/70 00:00      
         thanks            01/01/70 00:00      
         thanks, the circuit worked            01/01/70 00:00      
   LM339 is an open collector            01/01/70 00:00      
   As Aamir Javaid said about input to 8051.            01/01/70 00:00      
      Not for an open-collector output!            01/01/70 00:00      
         Is that tied to +5VDC            01/01/70 00:00      

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