White Noise Generator

LAJ · 20th March 2012, 06:25 PM

Has anybody used any of the Homedics sound machines for a white noise generator? That have white noise and several other noises on them.
I see them at the thrift shops for $1-$2 each which is probably less than you can build one for. Thanks.

LAJ · 22nd March 2012, 03:44 PM

It makes other sounds as well like a brooke running, birds chirping, rain falling.
I'm thinking that this will not disturb my neighbors as much when I am testing a high power amplifier on my back patio as a tone oscillator does.
And they won't call the cops on me.

Speedskater · 23rd March 2012, 06:57 PM

But I doubt that it's a technically correct "white noise" suitable for measurements.

LAJ · 26th March 2012, 04:20 PM

but have you seen what the MM5837 chips are going for on Ebay????
YIKES!!!!!! There's one for $10 and another for $23!!!!!!
Unbelievable!!!!!

RJM1 · 26th March 2012, 06:33 PM

White Noise.

LAJ · 28th March 2012, 03:21 PM

I built one of those before but using an op amp for the amplifier. I didn't think it worked very well.
But from the National Semiconductor 1980 Audio/Radio manual page 2-62 it states:
Unlike semiconductor noise sources, the MM5837 provides very uniform noise quality and output amplitude.
The MM5837 uses a clocked shift register to generate noise which I thought was a much better approach.

Osvaldo de Banfield · 28th March 2012, 03:33 PM

Long time ago I used a electrolytic cap reversed, and wired with a high resistance in series, limiting current so some microamperes, and acting as load, and using a 1 uF 50V powered from 12V, and it works very fine.

Frex · 28th March 2012, 03:34 PM

Hi Laj,

Did you have the spectrum profile of the noise generated by the MM5837 ?
I think for audio (and more) use, the application note DN70 from Linear Technology
is a very good solution.
Regards.

Frex

PChi · 28th March 2012, 04:14 PM

Hi,
I reverse engineered the internal circuit of I think the MM5837 and then built a version from shift registers (from memory I think that it's 17 stages) and Exclusive OR gates for generating a psuedo random digital signal. Used for testing Motorway 'Information' sign communication signals. The signal appeared pretty random on the valve oscilloscope that I used. I guess that up to the clock frequency it is a good white noise source.

BFNY · 28th March 2012, 04:16 PM

an analog FM tuner tuned to a blank point on the dial with no station works too.

20th March 2012, 06:25 PM	#1
LAJ diyAudio Member Join Date: Mar 2008 Location: Atlanta Ga. USA	White Noise Generator Has anybody used any of the Homedics sound machines for a white noise generator? That have white noise and several other noises on them. I see them at the thrift shops for $1-$2 each which is probably less than you can build one for. Thanks.

22nd March 2012, 03:44 PM	#2
LAJ diyAudio Member Join Date: Mar 2008 Location: Atlanta Ga. USA	I bought it for $1.68. It makes other sounds as well like a brooke running, birds chirping, rain falling. I'm thinking that this will not disturb my neighbors as much when I am testing a high power amplifier on my back patio as a tone oscillator does. And they won't call the cops on me.

23rd March 2012, 06:57 PM	#3
Speedskater diyAudio Member Join Date: Sep 2002 Location: Lakewood, Ohio	But I doubt that it's a technically correct "white noise" suitable for measurements. __________________ Kevin

26th March 2012, 04:20 PM	#4
LAJ diyAudio Member Join Date: Mar 2008 Location: Atlanta Ga. USA	Thanks Kev... but have you seen what the MM5837 chips are going for on Ebay???? YIKES!!!!!! There's one for $10 and another for $23!!!!!! Unbelievable!!!!!

28th March 2012, 03:21 PM	#6
LAJ diyAudio Member Join Date: Mar 2008 Location: Atlanta Ga. USA	Thanks RJM... I built one of those before but using an op amp for the amplifier. I didn't think it worked very well. But from the National Semiconductor 1980 Audio/Radio manual page 2-62 it states: Unlike semiconductor noise sources, the MM5837 provides very uniform noise quality and output amplitude. The MM5837 uses a clocked shift register to generate noise which I thought was a much better approach.


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28th March 2012, 03:33 PM	#7
Osvaldo de Banfield diyAudio Member Join Date: Dec 2011 Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina	Long time ago I used a electrolytic cap reversed, and wired with a high resistance in series, limiting current so some microamperes, and acting as load, and using a 1 uF 50V powered from 12V, and it works very fine. __________________ LW1DSE

28th March 2012, 03:34 PM	#8
Frex diyAudio Member Join Date: Nov 2009	Hi Laj, Did you have the spectrum profile of the noise generated by the MM5837 ? I think for audio (and more) use, the application note DN70 from Linear Technology is a very good solution. Regards. Frex __________________ DIY CS5381 ADC / DIY 10kHz Super Oscillator / DIY DC-1MHz RMS-DC converter & 60dB LNA .

28th March 2012, 04:14 PM	#9
PChi diyAudio Member Join Date: Jan 2012 Location: Staines, UK	Hi, I reverse engineered the internal circuit of I think the MM5837 and then built a version from shift registers (from memory I think that it's 17 stages) and Exclusive OR gates for generating a psuedo random digital signal. Used for testing Motorway 'Information' sign communication signals. The signal appeared pretty random on the valve oscilloscope that I used. I guess that up to the clock frequency it is a good white noise source.

28th March 2012, 04:16 PM	#10
BFNY diyAudio Member Join Date: May 2004 Location: Saratoga NY	an analog FM tuner tuned to a blank point on the dial with no station works too.

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