6V White Noise Circuit

Jan 06, 2012 47 Replies

I don't normally want too hot a noise source--something like photocurrent, which can be turned on and off, is just the ticket.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net

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Over what bandwidth?

-- Bill Sloman, Nijmegen

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Tens bucks is not too bad. I'd like to stick a low voltage zener into a TIA, and look at the current noise. I assume the impedance (at some current) is greater than that for a forward biased didoe.

George H.

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Yeah You get this random telegraph type signal, With lots more low frequency noise. I posted this 'scope shot in another thread.

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A 12 Volt zener near the knee.

Say that reminds me of a noise source I want to make some day. Some low level noise source running into a comparator (adjustable threshold) that triggers a one shot. (short pulse width adjustable height.)

The idea is to demonstrate how shot noise depends on the charge of the electron. Each pulse is an 'electron', the 'charge' is the height of the pulse. You measure the average current and noise and show that a few 'big fat electrons' give more noise than an equal average current of little electrons.

George H.

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That's interesting. Noiser in amplitude or in bandwidth?

George H.

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Well it's simple enough to turn off the bias current of a diode.

I guess the only issue with photocurrent is you have to get the photo from some place.

George H.

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Maybe, maybe not. While i am not totally ignorant of such math i suspect i would struggle with a proof either way. I still want to get ahold of Dr. Golds paper on maximally orthogonal PRN codes.

?-)

20 - 50k. Do you think the result (transistor vs diode) is going to change drastically?

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