Shop OBEX P1 Docs P2 Docs Learn Events
crystal oscillator tunner question — Parallax Forums

crystal oscillator tunner question

stbrnrdstbrnrd Posts: 35
edited 2005-08-13 21:52 in BASIC Stamp
Hello smarter people...
is there such a thing as a crystal oscillator tunner?
what kind of crystal oscillator could i use to generate 1200 BAUD (besides the 4.4336 mhz crystal)
is it possible to make the bsx2 simulate a 4.4336mhz signal? the crystal oscillator needed is a bit difficult to obtain.
it would be greatly appreciated smile.gif

Comments

  • dandreaedandreae Posts: 1,375
    edited 2005-08-12 23:46
    What is it that you actually trying do?



    Dave

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Dave Andreae

    Tech Support
    dandreae@parallax.com
    Http://www.parallax.com

    ·
  • stbrnrdstbrnrd Posts: 35
    edited 2005-08-13 01:03
    trying to incorporate the bsx2 with a tcm3105 for an fsk project
    trying to tie the freqout feature of the bsx2 to run the timing (oscillator) for the fsk chip

    if you have a way...i could sure use the guidance
    thanks in advanced
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-08-13 03:06
    Hello,

    ·· That's not going to work.· If the chip requires a crystal or resonator, you will need it.· The BASIC Stamp will not replace/substitute a precision clock source.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • stbrnrdstbrnrd Posts: 35
    edited 2005-08-13 03:25
    thanks!!... i just thought that it was possible :-(
    but i least i know now.
    so there are no "tunable" oscillators?? they are just made to a certain freq??
  • ForrestForrest Posts: 1,341
    edited 2005-08-13 05:50
    www.digikey.com sells Cardinal Components programmable oscillators for about $8. That price includes the programming for your desired frequency at Digikey.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2005-08-13 05:57
    What you are looking for is a programmable PLL (phase locked loop)
    ...or a programmable frequency synthesizer might work for you.

    http://www.uoguelph.ca/~antoon/gadgets/pll/pll.html

    http://members.tripod.com/~Malzev/comp/mb1505.htm
    http://www.cbsite.nl/modif/onderdelen/mc145106.htm

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-08-13 20:49
    Beau's idea will be the best course for you to handle.· Not many people cutting/tunig crystals these days in the hobby world.· Although in lower frequency systems they do make adjustable caps which can be used in oscillator circuits to tune the exact frequency.· Again, this is for lower frequencies.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • SPENCESPENCE Posts: 204
    edited 2005-08-13 21:52
    IF YOUR CRYSTAL IS BELOW ABOUT 12 MHZ RANGE AND IF IT IS IN A HOLDER THAT CAN EASILY BE DISASSEMBLED AND IF IT IS NOT A PLATED TYPE YOU CAN LOAD THE CRYSTAL FROM ZERO TO MAYBE 4 KHZ DOWNWARD. YOU USE PENCIL GRAPHITE LEAD OR SOLDER. BEND SOLDER INTO A TIGHT U . BE CAREFULL NOT TO GET ROSEN OF ACID ON THE CRYSTAL. DRAW A CIRCLE IN THE AREA 1/2 TO FULL CIRCLE OF THE SQUARE CRYSTAL. FT-243 HOLDERS ARE THE MOST COMMON USED BUT FT-241 AND DC-11 CAN ALSO BE MOVED DOWN. USUALLY ABOUT 6 TO 10 CIRCLES IS THE MAX BEFORE THE CRYSTAL QUITS OSCILLATING.. DRAW THE CIRCLES VERY LIGHTLY. REASSEMBLE AND TEST FREQUENCY AFTER EACH ADDITIONAL CIRCLE. IF YOU FILL IN THE CENTER BE VERY VERY LIGHT. THE SOLDER OR LEAD DEPOSIT SLOWS THE OSCILLATION THERFORE LOWERING THE FREQUENCY.

    TO MOVE A CRYSTAL UP YOU HAVE TO LAP GRIND THEM. TOOTHPOWER OR FINE CLEANSER POWERER IS WHAT I HAVE USED. BE READY WITH A GOOD SUPPLY OF CRYSTALS AND HOURS OF PRACTICE TO BE SUCCESSFULL. WASH CAREFULLY AFTER GRINDING BEFORE REASSEMBLING. PUT A SMALL PILE OF CLEANSER ON A PLATE OF WINDOW GLOAS ABOUT 6" SQUARE. WET NOT DAMPEN SO IT IS LIKE WATERY MUD. PUT CRYTALL IN THE MIDDLE OF THE MESS. PUT YOU INDEX FINGER CENTERED ON THE CRYSTAL AND MOVE IN FIGURE EIGHT PATTERN. DO THIS LIGHTLY ON BOTH SIDES. CLEAN REASSEMBLE AND TEST OFTEN. TO CHECK FOR ACTIVITY AND ACCURACY.

    WHEN REASSEMBLING, BE SURE THE METAL PLATES HOLDING THE CRYSTAL HAVE THE CORNERS BENT TOWARD THE CRYSTAL, NOT AWAY. THE CRYSTAL OCILLATES WHILE BEING SUPPORTED ON THE VERY CORNERS. IF YOU BREAK A CORNER OFF. DISCARD AND START OVER. IF WILL NO LONGER BE USEABLE. IF IT DOES OCILLATE IF MAY HAVE SPURIOUS FREQUENCIES WHICH ARE WAY OF FROM WHAT YOU WANT.

    KEY WORDS SLOWLY. CAREFULLY. VERY FRAGILE. GOOD LUCK COMES WITH MUCH PRACTICE.

    73
    SPENCE
    K4KEP

    PS. FORGOT TO MENTION. IF YOU HAVE A SUPPLY OF PICO FARAD 1-30 SAY. CAPACITORS YOU CAN PAD THE CAPACITOR LOWER ONLY IN PARALLEL. TRY PARALLELING SEVERAL IN PARALLEL WITH CRYSTAL.

    IF YOU ADD CAPACITORS IN SERIES IT SHOULD RAISE FREWENCY SLIGHTLY.

    S

    Post Edited (SPENCE) : 8/13/2005 9:56:41 PM GMT
Sign In or Register to comment.