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Variable Frequency — Parallax Forums

Variable Frequency

Eric REric R Posts: 225
edited 2007-06-27 19:37 in General Discussion
Anyone have any good ideas for varying 60hz 110 volts A/C very quickly between say 30.0 - 40khz?·(Not a VF drive as I do not think it would·ramp fast enough)

The load would only be a couple amps. I am thinking maybe taking the 110vac 60hz, converting it to DC, modify the frequency then convert back to 110vac with the new frequency.

any good ideas out there?

I plan to use the propeller for the frequency programming.

Comments

  • kjennejohnkjennejohn Posts: 171
    edited 2007-06-24 21:45
    I'm...confused.

    You want to convert 110/60 to DC (a linear power supply), then convert that to a higher frequency (a frequency generator) supplying a couple of Amps (a POWERFUL frequency generator), then convert that back to DC (the back end of a switching supply), 'modify' the DC to a frequency (here we go again), and lastly change THAT to 110/60 (at 2 Amps or so?). You start with 110/60 and end with 110/60. Why did you bother with all that stuff in between? I'm intrigued. What did I miss here?

    'Luck!

    kenjj
  • stamptrolstamptrol Posts: 1,731
    edited 2007-06-24 21:56
    I'm sort of with kenjj.....a bit confused.

    I understand wanting to change frequencies for certain jobs. I agree, a VFD is certainly not going to get up to that frequency.

    But what, pray tell, would need 110 volts at 40 kHz? Is this some kind of honking big ultrasonic thing?

    As usual, more details are better than fewer details when looking for help.

    Cheers,

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tom Sisk

    http://www.siskconsult.com
    ·
  • Eric REric R Posts: 225
    edited 2007-06-25 01:17
    Sorry for the confusion,

    110VAC 60hz line voltage input. End result output would be 110VAC 30.0 - 500hz variable.



    I wanted a wide range of adjustability but will settle for 500hz and expand later.



    Why you ask?

    60hz is a musical note. As you vary the frequncy, the note changes. I want to play music with voltage.
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2007-06-25 06:56
    Eric -

    There are frequency to voltage (F->V) chips as well as voltage to frequency (V->F) chips available, but none that I know of will work with line voltage. Besides that, line voltage would be rather dangerous for any sort of musical instrument in my mind.

    As far as specific chips are concerned, here is one which will go in either direction (V->F or F->V):
    http://focus.ti.com/docs/prod/folders/print/vfc32.html

    and, samples are available!

    Regards,

    Bruce Bates

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  • metron9metron9 Posts: 1,100
    edited 2007-06-25 08:53
    Eric, I am wondering if the 60hz hum on an amplifier is somewhere in your thinking behind this music making device. But that said, I am also confused as music heard through speakers is of course made with voltage so nothing new in that regard. Perhaps you can elaborate a bit more about what you plan to drive with this voltage? Giant speakers or perhaps a musical sparking device? Jacobs ladder keyboard? Something like that?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Think Inside the box first and if that doesn't work..
    Re-arrange what's inside the box then...
    Think outside the BOX!
  • SteelSteel Posts: 313
    edited 2007-06-27 19:37
    Wow...a 110V musical note? You realize that you only need 2 volts, right?
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