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OT: Does anyone have a good, simple random noise generator?

autodeskguest

Does anyone have a schematic for a good, simple random white noise generator.  I

want to use this for audio with a bandwidth up to 25KHz.  I am not particularly

interested in perfect statistical randomness.

 

Thanks in advance.

 

Steve

 

Parents

  • On Tue, 05 Aug 2008 23:07:28 -0400, Steve Jacobson <stevelists@jjworld.com>

    wrote:

     

    On Tue, 05 Aug 2008 17:44:33 -0700, Gary Gofstein <ggofstein@lbl_nospam.gov>

    wrote:

     

    just reverse bias the base emmitter junction of any normal transistor,

    NPN breaks down at about 7V. don't connect the collector. the transistor

    will be useless for any other purpose after this, it will appear to work

    but detailed measurements will show it is out of spec, so throw it away

    if you decide not to use it. 1ma is plenty of current. ac couple the

    transistor voltage to an op amp and voila! true analog white noise.

     

    Gary,

     

    What you are saying is to connect the base-emitter junction of an NPN transistor

    to a source greater than 7V.  Connect the base to +7V and the emitter to -7V.

    Ground the base and take the white noise off the emitter (coupled with a cap).

    Is this correct?  What noise voltage should I expect?

     

    Thanks for your help.  I hope I don't appear too dense.

     

    I will be running the thing at 9V.  Should I be using a current limiting

    resistor?  Also, what would be a good NPN transistor?

     

    Steve

     

Reply

  • On Tue, 05 Aug 2008 23:07:28 -0400, Steve Jacobson <stevelists@jjworld.com>

    wrote:

     

    On Tue, 05 Aug 2008 17:44:33 -0700, Gary Gofstein <ggofstein@lbl_nospam.gov>

    wrote:

     

    just reverse bias the base emmitter junction of any normal transistor,

    NPN breaks down at about 7V. don't connect the collector. the transistor

    will be useless for any other purpose after this, it will appear to work

    but detailed measurements will show it is out of spec, so throw it away

    if you decide not to use it. 1ma is plenty of current. ac couple the

    transistor voltage to an op amp and voila! true analog white noise.

     

    Gary,

     

    What you are saying is to connect the base-emitter junction of an NPN transistor

    to a source greater than 7V.  Connect the base to +7V and the emitter to -7V.

    Ground the base and take the white noise off the emitter (coupled with a cap).

    Is this correct?  What noise voltage should I expect?

     

    Thanks for your help.  I hope I don't appear too dense.

     

    I will be running the thing at 9V.  Should I be using a current limiting

    resistor?  Also, what would be a good NPN transistor?

     

    Steve

     

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