Good video but the output waveform is clearly being distorted by improperly biased gain transistors. It would be interesting to track down which stage is doing this and maybe even correcting it. The only thing we know is that the back biased PN junction in the first transistor is putting out white noise with a very large bandwidth...
I found that this does not work properly with 2N2222 NPN transistor used as the noise source. The 2N3904 works properly. I don't know why there is a difference.
The voltage level is critical, because the transistor is reverse-biased and needs to reach a breakdown threshold before it starts generating noise. I found on mine that the noise doesn't start until about 11V, and you get full noise output at 12V.
Thanks for the previous response, I've got the circuit up and running thanks to this video and your comment :) If I could, I have one more question for you: If I wanted to swap out the variable resistor for another one, which I could access easier, how can I know which resistance value to get? Or should I purchase a bunch and try them out? Thanks :)
The preset in the kit is marked 20k, so I would go for a potentiometer/variable resistor of the same value. Audio/volume potentiometers are usually logarithmic type (marked 'A') rather than linear ('B').
Great video thanks for the schematic, saved me loads of effort. I want to output through a speaker so need an amp Is there a video for the amp you used.
To be honest the brain blanks it out most of the time and you're only really aware of it when you think about it! The deafness that goes along with it is much more annoying but c'est la vie!
would I be able to power this with a guitar pedal power supply that outputs 12 volts? and if so, how could I connect it to the board? would a 12v dc power connector work? sorry, am brand new to this
Yes, that should work, although guitar power supplies that I have seen often have the power jack with the centre pin negative; the opposite of convention. I would always double check the polarity with a multimeter. Be careful connecting circuits like this to guitar effects units also, since commercial effects sometimes have the negative side wired to the audio input (so that it switches on when you put the guitar lead in). There is plenty of opportunity for shorting things out.
Hi Martin, thank you for this video. Unfortunately my circuit is creating a loud buzz and only gives me very quiet white noise when the gain is turned right down. Any ideas? Cheers Dave
Are you running off 12V? What I remember of this circuit is that it doesn't start to generate white noise until the voltage is a bit higher than 11V, as it uses the reverse breakdown of the transistor junction to generate the noise.
@@MartynDavies Thank you for replying, you are right although I am using an A23 12v battery, I just checked the volts when plugged into the system and its down to 10.5 volts. Thank you
Thank you for your video! :) But I didn't unterstand why C3 is there. Isn't this cap a short circuit for ac? Even though we want to amplify the ac signal?? 0.o
Indeed, C3 and R4 form a low pass in order to limit the upper noise frequency to a suitable value. But I think it acts too strictly, so I would suggest to reduce its value from 1 nF (not 10 nF as it was told in the video) to 330 pF.
You definitely could run it off batteries. It might also work a bit below 12V. The crucial part is Q1 - that needs to be reverse-biased enough to generate white noise.
Let's say I'm on the phone with someone. When I put this on a certain level that I can't really hear it, does the microphone of my phone hear it? Because if so, then that would mean the person I am talking to on the phone is hearing all the white noise while I can hear him.
Yes, a phone has two different channels of audio in the two directions: from your mic to his speaker and from his mic to your speaker. As long as the white noise is going into your mic and not your ear, only he can hear it.
So that means that if I put it on in my living room while I am calling with someone, it probably won't work because the white noise is not targeted specifically to the mic of my phone? By the way, the link from AliExpress in your description is not working.@@MartynDavies
It's not a transmitter - the white noise is an audio signal that comes out of the 3.5mm jack, so the only way it can get into your phone is if you have a speaker playing into the phone mic, or the audio is electrically connected in some way.
Link fixed now, but searching for 'white noise generator kit' on Aliexpress shows the kit available from a number of sellers at small variations of price.
Lol, all I got from this stupid kit was some horrible 50Hz squealing and screeching that changed its annoyance level by turning the little trimpot, not anywhere near white noise at all... :D
@@MartynDavies Yes, it was a 12V wallwart, I had no batteries at hand... and I think it's the culprit introducing the unwanted noise which the kit couldn't handle...
@Jorn Navarre Lol, yes, it was a crappy wallwart. I don't have a stabilized 12V supply at hand at the moment and 12V batteries are a bit of a hassle to put together with 1.5V cells ;)
