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  1. Path: sparky!uunet!olivea!decwrl!csus.edu!netcom.com!netcom!mjohnson
  2. From: mjohnson@netcom.Netcom.COM (Mark Johnson)
  3. Newsgroups: sci.electronics
  4. Subject: Re: CMOS Oscillator
  5. Message-ID: <MJOHNSON.92Aug18140900@netcom.Netcom.COM>
  6. Date: 18 Aug 92 22:09:00 GMT
  7. References: <1992Aug18.140051.10073@donau.et.tudelft.nl>
  8. Organization: Netcom Online Communications Service
  9. Lines: 44
  10. In-Reply-To: elmar@dutentb.et.tudelft.nl's message of 18 Aug 92 14:00:51 GMT
  11.  
  12. In article <1992Aug18.140051.10073@donau.et.tudelft.nl> elmar@dutentb.et.tudelft.nl (Elmar van Ginneken) writes:
  13.    > What I am looking for is a low power oscillator (<.5 mA @ 5V) running
  14.    > at a frequency of roughly 1 MHz.
  15.    > However, the frequency-determining component should be an inductor with
  16.    > a value of approx. 75 uH. (YES, I'm trying to measure inductance-change..)
  17.  
  18. The circuit below uses a single CMOS lowspeed 74C14 inverting Schmitt
  19. trigger chip, your 75uH inductor, and two 10K resistors.  It draws
  20. about 400uA and oscillates at about 4MHz.
  21.  
  22. The oscillator period will be approximately linearly related to the
  23. inductor value,   Period  ~=~  K1  +  ( K2 * L )   .   Note also that
  24. K1 will not be zero.
  25.  
  26.  
  27.                                                          ------------> Output
  28.                                                          |
  29.                                                          |
  30.          |\                |\                |\          |     |\
  31.          |  \              |  \              |  \        |     |  \
  32.          |    \            |    \            |    \      |     |    \
  33.   |------|     >O----------|     >O----------|     >O----+-----|     >O-----|
  34.   |      |    /            |    /            |    /            |    /       |
  35.   |      |  /              |  /              |  /              |  /         |
  36.   |      |/                |/                |/                |/           |
  37.   |                                                                         |
  38.   |                                          +5.0V                          |
  39.   |                                            |                            |
  40.   |                                            \                            |
  41.   |                                            /  R1                        |
  42.   |                              /|            \ 10K                        |
  43.   |                            /  |            /                 L1         |
  44.   |                          /    |            |                75 uH       |
  45.   |------------------------O<     |------------+---+----------)()()()(-------
  46.                              \    |                |
  47.                                \  |                /
  48.                                  \|                \  R2
  49.                                                    / 10K
  50.                                                    \
  51.                                                    |
  52.                                                   GND
  53.  
  54.  
  55. --MJ
  56.