Can someone please explain this circuit?


Closed Thread
Results 1 to 6 of 6
  1. #1

    Default Can someone please explain this circuit?

    Can someone please explain the attached circuit, Can output of this circuit be fed to the PIC?
    It is of a microwave motion sensor and I found this circuit on the internet, I have ordered this sensor module and would like to get some groundwork done in understanding the working of this circuit.

    My understanding is that this circuit amplifies the output from the sensor which is in few microvolts, but I would like to know what excatly does CW operation means, does it mean High/Low kind of output. Like High output when presence is there and Low when no movement is detected ?
    Attached Images Attached Images  
    ___________________
    WHY things get boring when they work just fine?

  2. #2
    Join Date
    Feb 2006
    Location
    Gilroy, CA
    Posts
    1,530


    Did you find this post helpful? Yes | No

    Default

    I can't, but the application/data sheet might help someone else. CW is continuous wave, versus pulsing the unit on and off to get the readings:
    Attached Images Attached Images
    Last edited by ScaleRobotics; - 21st July 2010 at 00:23.

  3. #3
    Join Date
    Aug 2006
    Location
    Look, behind you.
    Posts
    2,818


    Did you find this post helpful? Yes | No

    Default

    CW is as scalerobotics correctly stated Continious Wave. That's just a fancy way of saying an UnModulated signal, or just a carrier. Ham Radio uses this to send Morse Code, it is simply an interrupted carrier. The schematic shows a pulse train going into the circuit, this is a power saving technique which your PIC can provide. What to DO with the signal at the pre amp terminals. . . I have no clue.
    If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
    .
    Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
    .
    There simply is no "Happy Spam" If you do it you will disappear from this forum.

  4. #4
    Join Date
    Sep 2005
    Location
    Campbell, CA
    Posts
    1,107


    Did you find this post helpful? Yes | No

    Default

    The circuit amplifies the signal coming from the sensor by about 127,000 times. The high-frequency cutoff is around 500Hz.
    Charles Linquist

  5. #5


    Did you find this post helpful? Yes | No

    Default

    Quote Originally Posted by Charles Linquis View Post
    The circuit amplifies the signal coming from the sensor by about 127,000 times. The high-frequency cutoff is around 500Hz.
    So is it possible to count the pulses at the outpt using PIC then and take a decision based on that (i.e. the frequency)?
    ___________________
    WHY things get boring when they work just fine?

  6. #6
    Join Date
    Nov 2003
    Location
    Greece
    Posts
    4,116


    Did you find this post helpful? Yes | No

    Default

    Since the 2nd opamp is functioning as an integrator, no pulses are output.

    It is a filtered pure analog signal. So you need to acquire it by the A/D module of your controller.

    What you are going to do next is a matter of programming.

    You may have to look for rapid changes of the signal.

    An Osciloscope would help here alot.

    Ioannis

Members who have read this thread : 0

You do not have permission to view the list of names.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts