white noise controlled random number generator

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hey guys,
we have come up with a basic circuit with a BC-548 and LM-358N to generate white noise for a random number generating circuit connected to a x-bit number display that counts upto a certain random number and cuts-off unitil its reset again. we are trying to employ a counter to do this function. the problem we are facing is, we cant figure out, how we relate, and interface and convert this random noise spikes that are generated, into this counter.

Any suggestions n thoughts would be greatly appreciated.
 
Is that a microcontroller-based counter? Lots of microcontrollers have built-in A/D converters, that allow you to convert the analog noise voltage to a digital value for your counter.

See also: related thread;
on the PICList.
 
ericgibbs said:
hi,
For reference a Zener diode can be used as noise generator, 'pink' or 'white'.
Click to expand...

Presumably the BC548 mentioned is connected as a zener diode to create the noise?, it's the common method - it's actually white noise, pink noise is produced by filtering the white noise.
 

what about using a threshold detector and count the time between when a given threshold is exceeded. These times will be random and related to the noise.
 
Nigel Goodwin said:
Presumably the BC548 mentioned is connected as a zener diode to create the noise?, it's the common method - it's actually white noise, pink noise is produced by filtering the white noise.
Click to expand...


How do you mean? Have you got a circuit floating around somewhere?
 
lol, its random enough my my uses, and a quick analogue sample at the start on something (eg, a low cost RC circuit) gives a lot of starting places in the random table

Keep it simple stupid, that's my motto, unless things get ugly
 
gramo said:
lol, its random enough my my uses, and a quick analogue sample at the start on something (eg, a low cost RC circuit) gives a lot of starting places in the random table
Click to expand...

I've no problem with the random number sequence, it's just that you need a random number to seed it with!
 
Just like fighting fire with fire, you can combat noise with noise. White noise, sound frequencies spread equally across a given bandwidth, can be used to block out everyday sounds.
 
Generating a true random number with no bias is not trivial (see True random number generators).

One way to generate bits from a random noise source is to use a comparator to trigger at the zero crossings. You can then select arbitrary groups from this serial bit stream to form a digital number.
 
Many of the products claiming to produce white noise are recordings or simulations of wind, waves, and other sounds that are in reality quite a bit more complex than white noise.
 
I have actually designed exactly the circuit you describe. it is on my website. You dont need a zener diode (although this is traditionally the way to go). The input noise of an LM358 (or an LM324) is so bad, all you need to do is amplify this.

I just set up a dc bias voltage into an LM324 and amplified it with some dc blocking (to amplify only the noise). I then fed this into the ADC on a PIC and used this to generate a random number on an LED display that was displayed using the PIC.

it takes a bit of software to figure out, but is fairly straight forward. performing 100 tests on the output prove that the numbers very seldomly repeat. this is far more random that doing it in code with the input from a clocked source
 
White noise is also used for masking the symptoms of tinnitus, a medical condition defined by the National Institutes of Health as "hearing noises in your ears when there is no outside.
 
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