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Programmable Oscillator?

  1. Dec 26, 2006 #1
    Hello All,

    I'm wondering if there is such a thing as a programmable oscillator chip that I could use for my experiments. I want to work in the low MHz range (up to about 50MHz) but can't afford to buy a fancy frequency generator to accomplish the task; so, I got an old Motorola microcontroller and I want to see if I can use it to programmatically set the frequency for the oscillator. Does such a device exist?

    Thanks,
    Jason O
     
  2. jcsd
  3. Dec 26, 2006 #2

    Gokul43201

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    I know that programmable oscillator chips are quite standard, but:

    1. They typically come with some number (like 5) of preset frequencies, and if you want to continuously vary the frequency, you have to throw in a trimpot or some such extension.

    2. I've not seen a programmable oscillator that goes up to the MHz range - that is not to say that they don't exist.

    Have you looked up Analog Devices, Linear Technologies, Texas Instruments and other usual suspects?
     
  4. Dec 27, 2006 #3

    Gokul43201

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    http://www.analog.com/UploadedFiles/Data_Sheets/AD2S99.pdf

    That one goes up only to 20kHz, comes with 4 presets and allows you to add to it if you want more frequencies.

    Alternatively, you could build yourself a programmable oscillator based on a standard Wien Bridge topology. What's the budget and time restrictions on this? Also, what are your requirements on amplitude and frequency stability, and harmonic distortion?
     
  5. Dec 27, 2006 #4
    Hi Goku,

    Thanks for the suggestions. As for my requirements and time constraints. I need to build three of these oscillators to do my tests and I am working on this in my free time so no huge time constraints there. As for the budget, I'm definitely not rich but it would be nice to keep the cost to a minimum. However, the oscillator needs to be very frequency stable and have low distortion. I will ultimately be using it to trigger a DS1040 IC to control some MOSFETS. So the oscillator can be a square wave one. I do need to have a wide range of frequency control on this one. I have been trying to think about how to do this digitally. Maybe using a digital resistor or something if I used some sort of analog version? Not sure.

    Thanks,
    Jason O
     
  6. Jan 4, 2007 #5
    Hi Again,

    I'm thinking I might go for something a bit simpler for the moment so I thought i'd ask if anyone knows of any good, cheap, kits to build a pulse generator with an adjustable duty cycle. Ideally, it would be nice if I could make one that could up to about 1MHz but I'm not too picky about that. Any suggestions?

    Thanks,
    Jason O
     
  7. Jan 5, 2007 #6

    berkeman

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