Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Circuits for all noise generator

  1. Nov 2, 2005 #1
    i am trying to find a circuit diagram for a noise generator that can change between all the colours of sound. it is driving me made and was wondering if anybody can help please
  2. jcsd
  3. Nov 2, 2005 #2


    User Avatar
    Science Advisor

    There was a thread about white noise a little bit ago.

    Long story short, you can filter white noise into the other colors.

    http://rane.com/par-n.html#noise_color [Broken]
    Last edited by a moderator: May 2, 2017
  4. Nov 3, 2005 #3
    i need to get a circuit diagram for the filters and how to switch between them
  5. Nov 3, 2005 #4


    User Avatar

    Staff: Mentor

    I googled gyrator audio filter and got lots of hits. Here's a pretty good one to start you off:

  6. Nov 3, 2005 #5


    User Avatar
    Science Advisor

    fpop - if you know how to use an opamp then its somewhat simple, you can search for lots of circuit diagrams for filters. You simply switch between the outputs or could build a simple mixer to fade between them.

    What is this for?

    If you're demonstrating something, a computer with software like Cool Edit (now Adobe Audition or something) will let you generate and filter the signal to your heart's content in seconds and will be very easy to use in comparison.

    If you're doing something with audio gear, pink noise is the standard color because of its similarity to human hearing that roughly deems equal power per octave to be a 'flat' response. Look up Fletcher-Munson for a lot more detail on how the amplitude level affects this relationship.
  7. Nov 4, 2005 #6
    i need it for school i have to design and build a white noise generator that can switch between the colours using filters but i think im out of my depth
  8. Nov 4, 2005 #7


    User Avatar
    Science Advisor

    Sounds a little advanced. I found this diagram and it uses a three op-amps (ignore the bottom half of the pic).
    http://www.synthfool.com/schematics/polynoise.gif [Broken]

    You could just use a regular SPDT switch to go between the two colors but would need an output suitable for driving a speaker (if you don't have a power amp) and you also need a power supply for the opamps.

    I would think there would be an easier way to accomplish the task.
    Last edited by a moderator: May 2, 2017
  9. Mar 29, 2010 #8
    I too need http://www.speechprivacysystems.com/white-noise" to sleep and i always use an oscillating fan for years now as the noise of it puts me to sleep easily and also blocks out any background noise at nite i.e. car alarms, train whistle, dog barking etc.
    Last edited by a moderator: Apr 24, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook