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12kHz oscillator cct anybody?

Discussion in 'Electronic Basics' started by Martin Peters, May 12, 2005.

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  1. Hello,

    Any helpful soul out there able to point me to a schematic for a transistor
    (or 1 chip) cct that'll deliver a fixed 12kHz output?

    Thanks - Martin
     
  2. What waveform? How fixed?
     
  3. Chris

    Chris Guest

    Take a look at the LM555.

    http://www.uoguelph.ca/~antoon/gadgets/555/555.html

    One 8-pin IC (commonly available for less than a buck), along with one
    cap and two resistors. You can replace one of the resistors with a
    resistor and a pot to tweak it in to value.

    If this doesn't do the trick, possibly you might want to provide more
    information:

    For example: Sine, square, triangle, sawtooth? Logic level? How about
    duty cycle? Does it have to be 50% duty cycle, or is that important?
    Amplitude (voltage level)? How precisely do you have to hold the
    frequency? What's the load (what are you connecting to this)?

    Good luck
    Chris
     
  4. Sorry - sine wave, and stable enough so that when it's mixed (with SA602)
    with another signal which is then tuned with a radio in sideband mode, it
    won't require retuning after warm-up. This more improtant than actual
    accuracy of the 12kHz. 100Hz here or there not important.

    Thanks - Martin
     
  5. Brian Howie

    Brian Howie Guest

    --
    --
    Brian Howie
    SELEX Sensors and Airborne Systems Ltd
    Sensor Systems Division
    Crewe Toll Phase II, 1st Floor,
    Edinburgh EH5 2XS
    Phone +44 (0)131 343 8769
    FAX +44 (0)131 343 8941
    Email

    I read the thread.

    Use a Phase shift oscillator. DONT USE A 555.

    http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/oscphas.html

    Brian
     
  6. colin

    colin Guest

    in that case you probably need a crystal for stability, dividing it down to
    12khz, the most comon nearest is 32khz but this doesnt divied into 12 very
    well, you can get 'programable crystal oscilators', wich have internal
    divide by n counters. you can use a filter to clean the squarewave into a
    sinewave.

    or maybe you have another crystal oscilator somewhere in your circuit you
    can divide down ?

    Colin =^.^=
     
  7. John Fields

    John Fields Guest


    ---

    HC4066 +5
    +----------------------+ |
    +--|MR | [100R]
    | | | |
    GND | RS RTC Q8 | +--[3.6nF]--[50mH]-->>--+
    +-+------------+---+---+ | |
    | | | C [100R]
    +----[1M]----+ +--[1000R]---B 2N4401 |
    | | E +--->>--+
    | [500R] | |
    | | GND GND
    +---[XTAL]---+
    | |
    [10pF] [10pF]
    | |
    +------------+
    |
    GND

    The 4066 is being used as an oscillator and a divider, with the
    crystal frequency at 6.144 MHz. After being divided by 512, it exits
    the counter as a 12kHz square wave and is then sent through a bandpass
    filter to make the AC sine wave you need from it. I simulated it with
    LTC's SWCADII, and the netlist follows.

    The crystal is an Epson CA-301 6.1440M-C and the component values
    arount it are from a design guide they have at:

    http://www.eea.epson.com/go/Prod_Ad...rystals/go/Resources/TECHNOTES/OSCDESIGNGUIDE

    No guarantees, but it's a starting point!


    Here's the netlist:

    Version 4
    SHEET 1 880 680
    WIRE -224 432 -224 176
    WIRE -224 560 -224 512
    WIRE -224 592 -224 560
    WIRE -80 432 -80 384
    WIRE -80 560 -224 560
    WIRE -80 560 -80 512
    WIRE -64 176 -224 176
    WIRE -32 384 -80 384
    WIRE 80 384 48 384
    WIRE 144 176 16 176
    WIRE 144 336 144 176
    WIRE 144 560 -80 560
    WIRE 144 560 144 432
    WIRE 208 176 144 176
    WIRE 352 176 272 176
    WIRE 352 240 352 176
    WIRE 352 416 352 320
    WIRE 352 560 144 560
    WIRE 352 560 352 496
    FLAG -224 592 0
    SYMBOL voltage -224 416 R0
    WINDOW 123 0 0 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR InstName V1
    SYMATTR Value 5
    SYMBOL npn 80 336 R0
    SYMATTR InstName Q1
    SYMATTR Value 2N4401
    SYMBOL voltage -80 416 R0
    WINDOW 3 -30 212 Left 0
    WINDOW 123 -30 240 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR InstName V2
    SYMATTR Value PULSE(0 5 0 0 0 4.167E-5 8.33E-5)
    SYMBOL res 64 368 R90
    WINDOW 0 -37 56 VBottom 0
    WINDOW 3 -35 56 VTop 0
    SYMATTR InstName R1
    SYMATTR Value 1000
    SYMBOL res 32 160 R90
    SYMATTR InstName R2
    SYMATTR Value 100
    SYMBOL cap 272 160 R90
    WINDOW 0 -18 -15 VBottom 0
    WINDOW 3 -18 -20 VTop 0
    SYMATTR InstName C1
    SYMATTR Value 3.6E-9
    SYMBOL ind 336 224 R0
    WINDOW 0 -47 45 Left 0
    WINDOW 3 -66 80 Left 0
    SYMATTR InstName L1
    SYMATTR Value 50E-3
    SYMBOL res 336 400 R0
    SYMATTR InstName R3
    SYMATTR Value 100
    TEXT -258 648 Left 0 !.tran 0 .005 .004 uic
     
  8. Try a Wien-bridge oscillator build around an OpAmp, for 12 kHz even the
    venerable 741 should work. Any book on basic OpAmp circuits should cover
    this.
     
  9. Rich Grise

    Rich Grise Guest

    Nah. If you're going to be screwing with tuned circuits anyway, then
    use a crystal and divider chain, and a low-pass filter at its output.
    You can use your opamps for the low-pass filter. :)

    And where would you get a light bulb to use to stabilize a Wein bridge
    at opamp power levels anyway?

    Thanks,
    Rich
     
  10. David Eather

    David Eather Guest

    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA1

    You use a J-Fet biased by the output(I skipped a few details) not a
    light bulb for low power levels. It works beautifully ultra low
    distortion and if you want low frequencies below 1 Hz.

    -----BEGIN PGP SIGNATURE-----
    Version: PGP 8.1

    iQA/AwUBQr0+HJS9Fk5okqe7EQJ4xgCg5Zd49B45oWOy78Sy2KbxGfcvrAkAnigq
    RINAMc9iQQzuHpToA6WwyICg
    =8sZK
    -----END PGP SIGNATURE-----
     
  11. IIRC, the opamp datasheet from more than one mfgr has a Wien Bridge Osc
    in the apps section, and they usually use a 327 or other 28V .04A mini
    or submini lamp. Sometimes I see a 1869 bayonet base used. I think a
    possibly better one is the 12v .025A grain of rice lamps that Rat Snack
    sells (or used to sell). In any case, if you search for a WBO, you'll
    run across a number of them that use a lamp to stabilize the opamp.

    This one uses diodes so it tends to add distortion.
    http://www.ecircuitcenter.com/Circuits/opwien/opwien.htm

    If you want very low distortion, use a lamp. Here's more info on all
    types.
    http://sound.westhost.com/project22.htm

    And more info.
    http://users.telenet.be/educypedia/electronics/analogosciltypes.htm
     
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