XR2206 function generator

Discussion in 'The Projects Forum' started by onlyvinod56, Feb 17, 2009.

  1. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    Hi every one,
    Iam designing an AC to AC converter.
    as a part of this, ihave two options for for designing of pwm pulses firing circuit.
    1. XR 2206
    2. HEF 4752.
    I need to control the frequency of the inverter with a voltage.

    From this forum i came to know that XR2206 is used to produce a sample sinusoidal signal whose frequency can be varied with the voltage at pin1.

    anyways, in the datasheet i observed "frequency shift keying (FSK)".
    What is FSK?

    Is it really possible to control the frequency with an external voltage?

    thank you
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Take a look at page 5 of the PDF. You will observe that a selection between either of two discrete frequencies can be done. The selection is the keying, and going between the two frequencies is the frequency shift.

    Page 8 shows the arrangement to use a voltage to control frequency, page 11 describes the process.
     
  3. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    Thanks for your fast reponce.
     
  4. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    Hi,
    i didnt understand what is FSK. I have seen about FSK over the net. BUt i didnt understand its purpose here in this IC.

    Why a digital signal is modulated with respect to sinusoidal?

    anyways, i need to control the frequency over 0 ~ 200 Hz.

    which circuit i have to use from the pdf?

    see the attachment. can i use that test circuit? If so, what should be the FSK?
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    Ignore the FSK aspect. That is only significant in data signaling. You just want to be able to use an external voltage to slew the frequency. I do not know how closely you can approach 0 Hz.
     
  6. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
  7. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    That HEF4756 is an obsolete IC. If you have one, be careful - it will be hard to replace. The data sheet is only partial, so full information is not there.

    The "switch on delay" must be a power on delay to insure inputs are stable before firing up the inverter. Pin 24 - ?

    The example is for an LM556, so I would want to stay with that IC. Recall that the driver IC is no longer available as an off-the-shelf item.
     
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