white noise maker needed

Audioguru

Joined Dec 20, 2007
11,248
"Pointless and demeaning commentary deleted"
Who deleted my post and why?


Another insulting and pointless comment removed by moderator.
 
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THE_RB

Joined Feb 11, 2008
5,438
Two Cmos inverters form a square-wave generator, not a white-noise (random frequencies) generator.
One Cmos Schmitt-trigger inverter forms a square-wave generator. It also is not random.

A 3V battery quickly drops to 2V which is too low for an ordinary CD4xxx Cmos IC. Even a 74HCxxx Cmos IC will have an extremely low output current at 2V and 3V.
If I remember right it's pretty easy to make a white noise generator from CMOS gates or inverters. But i've never done it. :)

As for the output power, yes it's low but the CMOS outputs will drive rail to rail and with push-pull it will be QUITE audible even from say 2.5v which will put out close to 5v peak to peak. This I have done and a CMOS push-pull driver into an 8 ohm speaker (even with a safety series resistor) is annoyingly loud. It should be quite capable of making the "subtle" white noise to amuse baby.
 
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