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Problem with Phase sensitive detector example

Discussion in 'General Electronics Discussion' started by leeb_965, Feb 8, 2012.

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  1. leeb_965

    leeb_965

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    Feb 5, 2012
    Hello, I have been trying to make a PSD circuit using the attached. Can someone explain what the SYNC part of the circuit is? I have a strain gauge bridge circuit voltage which has been amplified by a 3-Op-Amp Instrumentation amplifier and this amplified voltage is the input to the PSD and someone says that the AC excitation supply should be used as the reference.

    Im not sure what this means. I tried using a CMOS 4053 as the switch and I flicked between the input voltage and the reference coming from the supply using a square wave generator but didnt get a rectified output.

    Can anyone offer any advice?

    Sorry forgot to upload the pic. Here it is.
     

    Attached Files:

    Last edited: Feb 8, 2012
  2. duke37

    duke37

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    Jan 9, 2011
    The problem seems to be that you have a one sided power supply so the voltages can never go negative. The switch must have its signal between the power rails.
     
  3. leeb_965

    leeb_965

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    Feb 5, 2012
    This was taken from a book I found. Can you suggest an alternative?
     
  4. duke37

    duke37

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    Jan 9, 2011
    You could use a power supply with a positive line and a negative line as in conventional op-amp supplies. The average input voltage is also critical and should be cetred around the new 0V line. The circuit as shown does not specify the input volts.

    I have had another look, there is no information on power supplies.
    Give us a complete diagram.
     
    Last edited: Feb 9, 2012
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