Hi all,
New here, and I have a question. I'm trying to build a white noise (maybe evolve into a pink noise with some filtering after I can reliably get white noise) generator for my daughter's room. I can do it with a simple arduino sketch but I was looking for something a little more...analog (simpler, in its way). I've been attempting to get a circuit running with a reverse biased NPN transistor and an opamp. I've been using an S8050 transistor with 9v on the emmiter and the base grounded. I was trying to view the noise coming off the transistor on a scope at my local makerspace, as I'm still saving up for a DS1054z. Unfortunately I get a strong 60hz signal in the lab from surrounding power/equipment at the makerspace and couldn't make out if I was actually getting noise from the transistor. I was hooking the positive lead to the emitter leg and the negative lead to ground (i.e. the base of the transistor). I wanted to know what sort of amplitude the noise was off of the transistor so I could calculate the gain I needed on a negative feedback op amp config. I have a few questions:
Is there a general expectation in terms of peak to peak voltage I'd be getting from the transistor in this configuration?
Is 9v sufficient to drive the zener effect on this kind of transistor?
Am I probing in the correct location?
Is there any other way (don't have an electro-magnetic quiet location at the moment) for me to take a look at the noise coming off of the transistor?
I'm basing my design off of the following:
http://electro-music.com/forum/phpbb-files/whitenoise_969.jpgI also have a wide range of zener diodes I could try this on if it's suggested that might be easier (at least I'd know the break down voltage). I'm not sure if I'd need to exceed that voltage or ride the breakdown voltage line to get clean white noise off of it though.
Thanks in advance!