Any suggestions for a digital ready random noise circuit? - Page 2 - Electronic Circuits Projects Diagrams Free

crutschow · 12th June 2008, 05:56 PM

Quote:

Originally Posted by audioguru

The emitter-base of a silicon transistor has avalanche breakdown at from 5V to 10V like a noisy zener diode. That is what Blue Bill has in his circuit then the nisey transistor is amplified by the second transistor.

Yes, it is similar to the zener circuit I posted.

But a significant difference is that the zener cathode is decoupled by a resistor and capacitor to eliminate negative feedback from the collector, which would otherwise significantly reduce the noise gain. That's probably why that circuit can generate 15V noise with only one stage.

Roff · 13th June 2008, 02:43 AM

It's difficult to get true average 50% duty cycle from an analog noise source, due to harmonic distortion, etc. Think about running the resulting digital signal through a fast (relative to your noise bandwidth) toggle flip-flop. The resulting signal should average 50% 1's and 50% zeroes, with the only error being the skew between propagation delays of clock-to-output on positive vs negative output transitions.

Ubergeek63 · 13th June 2008, 10:19 AM

Linear feedback shift register - Wikipedia, the free encyclopedia

dontronics.com (random.htm)

you could easily find many more variations

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13th June 2008, 02:43 AM	(permalink)
Roff	It's difficult to get true average 50% duty cycle from an analog noise source, due to harmonic distortion, etc. Think about running the resulting digital signal through a fast (relative to your noise bandwidth) toggle flip-flop. The resulting signal should average 50% 1's and 50% zeroes, with the only error being the skew between propagation delays of clock-to-output on positive vs negative output transitions. __________________ Ron Last edited by Roff; 13th June 2008 at 02:43 AM.

13th June 2008, 10:19 AM	(permalink)
Ubergeek63	Linear feedback shift register - Wikipedia, the free encyclopedia dontronics.com (random.htm) you could easily find many more variations