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Looking for a DDS module 10kHz-1MHz, 2Vrms sine into 50ohms

Discussion in 'Electronic Design' started by Joerg, Feb 3, 2013.

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  1. Joerg

    Joerg Guest

    For a tester project I need a DDS source, should be a module but with
    some decent output power and if possible a display. SPI or RS232 style
    control would be nice. So far I only found this kind:

    http://www.amazon.com/SG1005-Signal...TF8&qid=1359855256&sr=8-1&keywords=SG1005+DDS

    Some comments are not so enthusing though:
    http://www.elecfreaks.com/279.html

    Can't find a manual for it or any decent info. Does anyone know where,
    or has a suggestion for a better module? Need 10kHz to 1MHz (higher
    would be nice) range, 2Vrms or so sine wave into a 50ohms load. Price is
    not so important, can be $100/module.

    Hacking is no problem, for example to get around a RS232/USB chip
    because I can't really use USB. Sine wave quality doesn't have to be
    super stellar, slight distortion would be ok. But I can't use a big boxy
    function generator since it has to be integrated in the tester.
     
  2. Guest

    https://www.sparkfun.com/products/9169 ?

    you'd need a buffer but you said you didn't mind a bit of hacking


    -Lasse
     
  3. Jon Kirwan

    Jon Kirwan Guest

    http://www.ebay.com/itm/DDS-LCD1602..._Measurement_Equipment_ET&hash=item43b0446aa6

    Several kinds of outputs, 50 ohm, ttl, etc. Even has a knob
    and comes with power, too. But since it is Hong Kong, I'd
    write and make sure they know it's going to 60Hz, 110VAC so
    they provide the RIGHT part with it.

    Jon
     
  4. Jon Kirwan

    Jon Kirwan Guest

  5. Joerg

    Joerg Guest

  6. Joerg

    Joerg Guest

    That seems to be the very same module as in my link. It comes under all
    sorts of part numbers and names.

    What I (so far) have not found is any useful documentation about these
    boards.
     
  7. Joerg

    Joerg Guest


    Yes, those can be bought everywhere. But no LCD, no output buffer amp,
    bare bones. Those are almost like buying the bare chip. I am looking for
    something I can screw into a tester and have some local control as well.

    Worst case I'll have to order a module like in my link and reverse
    engineer it so I can arrive at a hack that makes it work in our tester.
     
  8. Guest

    but then you'll need a pcb, xtal regulator, etc. and have to build it
    with this you just need a buffer amp. You don't have something laying
    around with ~3-4x gain that can drive 50R?


    -Lasse
     
  9. Joerg

    Joerg Guest

    Oh, I can build it, just a simple amp. But another board to be roached
    in. If it has to be that way then so be it. I'd also have to build an
    LCD module, plus some sort of encoder for local control.
     
  10. Guest

    I see, if you don't have anything to control it with then it is a bit
    more work than just a buffer

    how about something like this: http://imall.iteadstudio.com/im120723003.html

    open source hard and software, even comes with a programmer if you
    want to
    do you own software


    -Lasse
     
  11. Joerg

    Joerg Guest

    Thanks! That looks like a very good candidate. Not sure why it needs 4W
    of power but I can supply that. The display looks like the one on my
    Nokia phone so should have a backlight. If not we'll just supply
    flashlights :)

    I don't like that open coil switcher inductor, makes for lots of EMI.
    But this my home turf so I can deal with that.
     
  12. Joerg

    Joerg Guest

    Someone demo'ed it on Youtube:



    Looks nice. The frequency dialing is weird through. CCW makes it go up,
    maybe the programmer is also designing faucets :)

    I guess since the firmware is open one can correct for oddities like that.

    A bit concerning is the frequency instability mentioned here but that
    may have to do with the switch mode converter on there:

    http://blog.tkjelectronics.dk/2011/09/review-iemp-v1-0-simple-arduino-dds-signal-generator/

    Instability is a showstopper for me but hopefully it's just a minor
    screw-up that can be corrected.
     
  13. Q: What did Joerg say to his girlfriend at the restaurant
    teble when they went out together to dine on the Valentine's?









    A: "What would you like to order, my sweet dear little fattie?"

    Regards,
    Mikko
     
  14. Joerg

    Joerg Guest

    I looked in that market and most of the DDS are quite deeply embedded in
    a transceiver or receiver. Like this:

    http://www.nikkemedia.fi/juma-tx1/

    I have even seen a DDS synthesizer in a tube amplifier somewhere.

    The filter usually doesn't have to be adjusted in a DDS unless the
    master clock or something like that is changed.
     
  15. Tauno Voipio

    Tauno Voipio Guest

    Yep. The leading brand is HK Blue.

    But it is damn good when roasted on a stick like
    marshmallows in the big West.
     
  16. Joerg

    Joerg Guest

    Have you ever tried Johnsonville Brats? (Bratwurst). Roasted over a wood
    fire, outdoors, yumm. I could eat 3-4 in a row but of course that's not
    healthy so I restrict myself to one.

    Nothing better than standing around the fire with a beer in hand,
    discussing politics, cars and football :)
     
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