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Re: [Electronics_101] Re: 2mHz to 6mHz signal generator

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  • Howard Hansen
    At one time the favorite function generator IC was the MAX038. It generated frequencies up to 20 megahertz. However,it is no longer available. About the
    Message 1 of 33 , Oct 5, 2011
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      At one time the favorite function generator IC was the MAX038. It
      generated frequencies up to 20 megahertz. However,it is no longer
      available. About the only function generator IC still available is the
      XR2206. But it only generates frequency up to 1 megahertz.

      Doing a search on Ebay using the phrase "DDS signal generator" turns up
      quite a few signal generators that cover the frequency range from 1
      hertz to 5 megahertz with sine wave, square wave and triangle outputs.
      However, some of the lowest cost items have the highest highest shipping
      charges. For example one unit had a buy it now price of $17.49 plus
      $63.00 shipping.

      With the limited time I spent checking prices the lowest total cost I
      found was $44.50, $10.00 + 34.50 shipping. See
      <http://www.ebay.com/itm/NEW-SG1005-Signal-Generator-Source-Module-DDS-Function-LCD160-Display-5V-/250904858739?pt=LH_DefaultDomain_0&hash=item3a6b185073>

      It looks like if you need to get up and running quickly your best bet is
      either use a 555 or buy a DDS signal generator on Ebay.

      Howard




      On 10/5/2011 8:12 AM, orvillefpike wrote:
      >
      > The AD9835 doesn't seem to generate square wave but the AD9837 and the
      > AD9833 seem to.
      > I agree with you, it seems like a great device.
      > Is there a device that will generate a signal from 2MHz to 6MHz that
      > is set up like a bit like a 555?
      > I should use that first because it would take me too much time setting
      > up a AD9835. I would use an AD9835 later once I learn how to use it.
      >
      > Thanks
      >
      > --- In Electronics_101@yahoogroups.com
      > <mailto:Electronics_101%40yahoogroups.com>, "Michael" <mmk_tsm@...> wrote:
      > >
      > > The AD9835 looks like a fantastic device. Can you generate square
      > waves with it?
      > > Mike.
      > >
      > >
      > >
      > >
      > > --- In Electronics_101@yahoogroups.com
      > <mailto:Electronics_101%40yahoogroups.com>, Howard Hansen <hrhan@> wrote:
      > > >
      > > > On 10/4/2011 10:16 AM, orvillefpike wrote:
      > > > >
      > > > > Is there an IC that could generate a signal from 2mHz to 6mHz?
      > > > > Ideally this IC could be controlled by a microcontroller, but
      > this is
      > > > > not a must.
      > > > >
      > > > > Thanks
      > > > >
      > > > > __._
      > > > Sparkfun sells a breakout board with an AD9835 signal generator
      > mounted
      > > > on the board for $35.00 that can do much more than you specified
      > above.
      > > > See:
      > > > <http://www.sparkfun.com/products/9169>
      > > >
      > > > It can be controlled by a micro controller. Check out the ":App note"
      > > > and the comments on the Sparkfun web page. One of the comments
      > provides
      > > > code for controlling the AD9835 with an Arduino Uno.
      > > >
      > > > Howard
      > > >
      > > >
      > > >
      > > > [Non-text portions of this message have been removed]
      > > >
      > >
      >
      >



      [Non-text portions of this message have been removed]
    • orvillefpike
      The PWM from a uC wouldn t work because, as stated, the frequencies selection is too coarse. A uC controlled oscillator, like a AD9833, could work though. I
      Message 33 of 33 , Oct 16, 2011
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        The PWM from a uC wouldn't work because, as stated, the frequencies selection is too coarse. A uC controlled oscillator, like a AD9833, could work though.
        I think I solved the oscillator problem, for now, by using a 74HC4046. Now my problem is, I want to drive the two legs of a center tap transformer and feeding each leg alternatively with a positive pulse and I also need a dead time so the two transistor don't conduct at the same time.
        A SG3525 would do if it went hihg enough in frequency.

        --- In Electronics_101@yahoogroups.com, "rtstofer" <rstofer@...> wrote:
        >
        > This might be possible with one of the DSS capable microcontrollers like the Analog Devices Blackfin but I don't think it is possible with just an Arduino.
        >
        > The Arduino runs at 16 MHz (Blackfin at 500 MHz) and if we wanted only 8 steps in a synthesized sine wave of 6 MHz we would need to set the analog output at a 48 MHz rate. And that's just 4 steps on the positive side and 4 steps on the negative side of the sine wave. Or, 2 steps on the rising slope and 2 steps on the negative slope of each half.
        >
        > Creating an arbitrary frequency (like 5.379 MHz) is very difficult with binary division of a clock. There is no direct way to divide by anything other than whole numbers so the very first bit divides the clock in half. What is needed is a phase locked loop (PLL) which can generate somewhat arbitrary frequencies by first multiplying the incoming clock up to, say, 600 MHz and then dividing. The limiting factor is how fast the voltage controlled oscillator (VCO) can run.
        >
        > And I think that is what the signal generator chips are all about.
        >
        > Richard
        >
        >
        > --- In Electronics_101@yahoogroups.com, Gavin Dingley <gavin.dingley@> wrote:
        > >
        > > Well, you could use a
        > > microcontroller in the first place; with such a low frequency you can
        > > use pulse width modulation, with a pulse frequency of ten times the
        > > highest frequency of interest. As a first cut you could use a Aduino,
        > > which has analogue ouputs that are pwm. Write a program that generates
        > > the sine wave values and send them to one of the analogue pins, then a
        > > low pass filter is used that has a cut-off at the pwm frequency, which
        > > should give use the desired waveform.
        > >
        > > Gavin
        > >
        > >
        > > ________________________________
        > > From: orvillefpike <orvillefpike@>
        > > To: Electronics_101@yahoogroups.com
        > > Sent: Tuesday, 4 October 2011, 16:16
        > > Subject: [Electronics_101] 2mHz to 6mHz signal generator
        > >
        > >
        > >  
        > > Is there an IC that could generate a signal from 2mHz to 6mHz?
        > > Ideally this IC could be controlled by a microcontroller, but this is not a must.
        > >
        > > Thanks
        > >
        > >
        > >
        > >
        > > [Non-text portions of this message have been removed]
        > >
        >
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