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???
03/07/11 15:14
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 		 #181477 - Yes, mentioned but maybe missed
Responding to: ???'s previous message
Aubrey Kagan said:
I appear to be joining this conversation a little late, but it appears that no one has mentioned the following level shifting technique for AC signals. Feed the AC signal to a large (low impedance at the desired frequency) capacitor and then connect the other side of the capacitor to the centre of a resistor divider (say 47K/47K) connected between Vcc and gnd. The signal will oscillate around Vcc/2.

See my post from 2011-03-06 19:09.

List of 28 messages in thread
TopicAuthorDate
Adding a DC biac to a bipolar signal?            01/01/70 00:00      
   summing            01/01/70 00:00      
      Resitor bias            01/01/70 00:00      
         Yes, mentioned but maybe missed            01/01/70 00:00      
   What about the character of the signal?            01/01/70 00:00      
      Information content..            01/01/70 00:00      
         Hardly....            01/01/70 00:00      
            So the only option would be software RMS?            01/01/70 00:00      
               100Hz or 100 beats per minute?            01/01/70 00:00      
                  100Hz.            01/01/70 00:00      
                     50-150Hz is in the range of AD637!            01/01/70 00:00      
                        That's great! (but some other concerns...)            01/01/70 00:00      
                           Can you show us a typical signal?            01/01/70 00:00      
                              A Typical EMG Signal            01/01/70 00:00      
                                 Probably tough for rms chi            01/01/70 00:00      
                                    I'm working with a dsPIC            01/01/70 00:00      
                                       Shouldn't be too expensive            01/01/70 00:00      
                                 Give the AD637 a try...            01/01/70 00:00      
                                    Look at LTC1966            01/01/70 00:00      
                                       Interesting...            01/01/70 00:00      
                                          Just received a fresh new batch of AD637s            01/01/70 00:00      
               Negative supply voltage available?            01/01/70 00:00      
   Does your system have a driven electrode?            01/01/70 00:00      
   better be careful            01/01/70 00:00      
      Regrowth            01/01/70 00:00      
         are you suggesting that humans are expendable?            01/01/70 00:00      
            All precautions taken.            01/01/70 00:00      
            Obviously            01/01/70 00:00      

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