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 Forum index » DIY Hardware and Software
DIY NPN Transistor Whitenoisegenerator from scratch
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2kohm



Joined: Feb 19, 2013
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PostPosted: Mon Apr 01, 2013 10:06 am    Post subject:  DIY NPN Transistor Whitenoisegenerator from scratch
Subject description: npn reverse bias junction
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NPN Whitenoise generator with opamp amplifier





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NPN Whitenoise gen with opamp amplifier
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Osal



Joined: Aug 16, 2011
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PostPosted: Thu Apr 04, 2013 4:15 am    Post subject: Reply with quote  Mark this post and the followings unread

To make the video of the breadboard it is a very nice the idea! Very Happy

May I ask why you didn't connect the op-amp's non inverting input to ground?

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isak



Joined: Dec 13, 2009
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PostPosted: Thu Apr 04, 2013 7:55 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool!
Is it 741 IC?
Can I use 15V to run it?

Cheers Smile

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2kohm



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PostPosted: Thu Apr 04, 2013 10:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you guys Smile

one blemishes Smile but it makes no audible difference.

yes! i used the UA741 veteran Smile tested also with lm324 tl072 tl07X.
I think every singel opamp works!

15 v not tested but i think it works also


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isak



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PostPosted: Thu Apr 04, 2013 11:48 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks man.
Looks and sound good Smile

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2kohm



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PostPosted: Thu Apr 04, 2013 12:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

thanks Smile

i try to convert it in a pink noise and some random noise modes.

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Cynosure
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Joined: Dec 11, 2010
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PostPosted: Thu Apr 04, 2013 3:23 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice! Thanks for posting the response charts.
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beesontoast



Joined: Feb 03, 2014
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PostPosted: Mon Feb 03, 2014 9:33 am    Post subject: Darn it, I can't make it work! Reply with quote  Mark this post and the followings unread

I can make most things work, given time, but this - despite its elegant simplicity - has me stumped.

I have used all-new parts, tested them all (the 741 by substitution) and double-checked connections. I have tried it on a speaker, a 386 op-amp, a small but very sensitive amp I use for other projects, and earphones and I get nothing, nada.

If there was one component I should try varying a value for, which would you suggest?
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2kohm



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PostPosted: Tue Feb 04, 2014 2:50 am    Post subject: Reply with quote  Mark this post and the followings unread

hi,

try the Transistors 2N2222A and BC457

C2 = 47N
C3 = 27N

for different noises


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beesontoast



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PostPosted: Tue Feb 04, 2014 4:16 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks - I will play some more.

One thing though - you have + (pin 3 on a 741) on the op-amp going to ground on that diagram...

Your drawing of a PP3 also shows reversed polarity...

Last edited by beesontoast on Tue Feb 04, 2014 5:00 am; edited 1 time in total
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2kohm



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PostPosted: Tue Feb 04, 2014 4:23 am    Post subject: Reply with quote  Mark this post and the followings unread

that makes no difference for me
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beesontoast



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PostPosted: Tue Feb 04, 2014 5:19 am    Post subject: Reply with quote  Mark this post and the followings unread

I can make some pretty weird noises by coupling it to a 386 op-amp and ignoring pin 3 as per the original circuit - something like a cow with bellyache attacking a duck...

But nothing remotely like white noise.

Oh - I also made a pretty fair EMF detector by putting a coil and a 100nf in series between pins 2 and 3.
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2kohm



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PostPosted: Tue Feb 04, 2014 5:56 am    Post subject: Reply with quote  Mark this post and the followings unread

which transistor did you use?
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beesontoast



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PostPosted: Tue Feb 04, 2014 6:19 am    Post subject: Reply with quote  Mark this post and the followings unread

I tried a PN2222, BC517 and currently BC547B.
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beesontoast



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PostPosted: Thu Feb 06, 2014 1:06 pm    Post subject: Reply with quote  Mark this post and the followings unread

I have solved the problem I had with the first circuit by adding in a potentiometer, and it turns out with a resistance of about 240 ohms I get white noise in a single 16 ohm earpiece.

(added) It turns out that a small electrolytic in that position also does the job.
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2kohm



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PostPosted: Thu Apr 10, 2014 4:35 am    Post subject: Reply with quote  Mark this post and the followings unread

good that it works now
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beesontoast



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PostPosted: Thu Apr 10, 2014 8:45 am    Post subject: White noise generator using LM386
Subject description: circuit diagram
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Here's my LM386 version:

It will oscillate at lower voltages, but seems to require a full 12v to produce white noise.

https://www.dropbox.com/s/luvp9vtbp5nup5y/2014-05-02%2009.10.26.jpg

Last edited by beesontoast on Fri May 02, 2014 1:17 am; edited 1 time in total
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555



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PostPosted: Thu May 01, 2014 5:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

beesontoast wrote:
I have solved the problem I had with the first circuit by adding in a potentiometer, and it turns out with a resistance of about 240 ohms I get white noise in a single 16 ohm earpiece.

(added) It turns out that a small electrolytic in that position also does the job.


Hi

Where exactly did you connect the potenciometer? i have the same problem than you, i almost tried everything, but i can't fix the problem (i spend hours try to realize what is wrong )
thanks!
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beesontoast



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PostPosted: Fri May 02, 2014 1:19 am    Post subject: Reply with quote  Mark this post and the followings unread

555 wrote:


Where exactly did you connect the potenciometer? i have the same problem than you, i almost tried everything, but i can't fix the problem (i spend hours try to realize what is wrong )
thanks!


In place of the 1M resistor. It does seem to be important to use a 12v supply - 9v does not work.
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555



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PostPosted: Fri May 02, 2014 8:01 am    Post subject: Reply with quote  Mark this post and the followings unread

beesontoast wrote:
555 wrote:


Where exactly did you connect the potenciometer? i have the same problem than you, i almost tried everything, but i can't fix the problem (i spend hours try to realize what is wrong )
thanks!


In place of the 1M resistor. It does seem to be important to use a 12v supply - 9v does not work.


Thanks!

i was suspecting that does't work with a 9v battery, anyway i will try the potenciometer, thanks
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narges_1992



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PostPosted: Thu Sep 11, 2014 3:19 am    Post subject:
Subject description: hi can you tell me about the ampilifier of this circuit , i have problem to produce this sound
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Sad Confused
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