Simple white noise circuit with 5V? SN76489 ?

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Yekuku
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Simple white noise circuit with 5V? SN76489 ?

Post by Yekuku » Mon May 04, 2020 10:30 am

HI guys,
I am building a DIY synth and i would like to add a white noise generator thats is powered from 5V.
I looked everywhere for a such a schematic but I could not find any . Is it possible to generate white noise from 5v and keep things simple ?
Anyways,
I found a few SN76489 that include a white noise generator and they are powered from 5v and I am wondering if there is a simple way to create white noise without using a microcontroller.
I have found a demo circuit for the 76477 which is similar to the 76489.
Image
Has anybody used the 76489 for such applications? Any ideas about what circuit is needed ?
Do I have any other options for a simple 5v noise generator ?

Many thanks !

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Mon May 04, 2020 11:54 am

Using that SN76477 I think would be overkill, if only used for it's noise.

Try Googling:
Transistor noise generator
or
40106 noise generator

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by socom93 » Mon May 04, 2020 11:58 am

Hey,
you should look at this post from the electro music forum :http://electro-music.com/forum/topic-46527.html

But it's seems hard to make it work well at only 5V, why only 5V if i may ask ?

Another solution would be to use the electric druid NOISE2 chip which has white and pink noise but well it's not DIY at this point ahah. Hope you find a way

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by Yekuku » Mon May 04, 2020 12:42 pm

BartBral wrote:
Mon May 04, 2020 11:54 am
Using that SN76477 I think would be overkill, if only used for it's noise.

Try Googling:
Transistor noise generator
or
40106 noise generator
haha, overkill it is :)
unfortunately I have already looked about it, I am interested in 5V operation, transistors need at least 7 volts to produce noise and the CMOS circuit needs extra power rails.
socom93 wrote:
Mon May 04, 2020 11:58 am
Hey,
you should look at this post from the electro music forum :http://electro-music.com/forum/topic-46527.html

But it's seems hard to make it work well at only 5V, why only 5V if i may ask ?

Another solution would be to use the electric druid NOISE2 chip which has white and pink noise but well it's not DIY at this point ahah. Hope you find a way
I did my search in the forum, but a 5V solution was not found :(
I am building a synth based on a monotron delay, and i would like to add some important features like white noise, envelopes, S&H without having to add more voltage rails than the 5V. I am no DIY synth Guru, I am just learning by building stuff.
I did not know about the NOISE2 chip, thank you very much for mentioning. If I dont find a solution , this could be come handy :)

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Mon May 04, 2020 1:13 pm

Another solution would be to use the electric druid NOISE2 chip which has white and pink noise but well it's not DIY at this point ahah. Hope you find a way
What is the definition of DIY?

The assembler code can be found here:
https://www.electricdruid.net/code/NOISE2.ASM

If puting a .hex file on a micro-controller is still DIY:
https://www.electricdruid.net/code/NOISE2.HEX

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by Yekuku » Mon May 04, 2020 1:47 pm

haha, many thanks Bart :) I dont have a 16F18313 PIC but I am wondering if there are alternative PICs to use.
About the cmos noise that you have suggested, I had a totally different circuit in mind , it turns out that there is hope.
I have checked the schematics and it is powered from 9V, the 40106 can run from 3V to 18V, so it is worth trying , the problem is that I dont have any 40106 lying around and due to the quarantine I cant get any soon.
Here is the schematic:
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Re: Simple white noise circuit with 5V? SN76489 ?

Post by jorg » Mon May 04, 2020 2:42 pm

https://en.wikipedia.org/wiki/Linear-fe ... t_register

You can slap one of these together with a few logic chips (e.g. CD4000 series).

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Mon May 04, 2020 2:53 pm

I dont have a 16F18313 PIC but I am wondering if there are alternative PICs to use.
I think you could, but to be honest I'm not smart enough to program in assembler, so I can't tell you how to change the code for other PICs...

As we speak others are exchanging ideas of how to do a noise-generator with his brother/sister... the ATTiny/ATMega:
viewtopic.php?f=17&t=231151
Have you seen that? There might be some good advice there...

Good luck!

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by socom93 » Tue May 05, 2020 4:41 am

Yekuku wrote:
Mon May 04, 2020 1:47 pm
I have checked the schematics and it is powered from 9V, the 40106 can run from 3V to 18V, so it is worth trying , the problem is that I dont have any 40106 lying around and due to the quarantine I cant get any soon.
That's a good choice, the 40106 can easily work with 5V, you should check the noise source schematic from an 808 hihats.
BartBral wrote:
Mon May 04, 2020 1:13 pm
What is the definition of DIY?
Good question, some might say that using chips like CEM3340 is at the boundaries of DIY since it's almost a VCO on a chip.
What is your definition ahha

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Tue May 05, 2020 8:38 am

socom93 wrote:
Tue May 05, 2020 4:41 am
Yekuku wrote:
Mon May 04, 2020 1:47 pm
I have checked the schematics and it is powered from 9V, the 40106 can run from 3V to 18V, so it is worth trying , the problem is that I dont have any 40106 lying around and due to the quarantine I cant get any soon.
That's a good choice, the 40106 can easily work with 5V, you should check the noise source schematic from an 808 hihats.
Uhhhmmm, have you seen the TR-808 schematics? It is actually Transistors in the noise-generator. I think you mean the TR-909 instead. That uses 4006 shift registers.
https://www.ti.com/lit/ds/symlink/cd400 ... 8685754789
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Re: Simple white noise circuit with 5V? SN76489 ?

Post by EATyourGUITAR » Tue May 05, 2020 9:02 am

Yekuku wrote:
Mon May 04, 2020 12:42 pm
I am interested in 5V operation, transistors need at least 7 volts to produce noise and the CMOS circuit needs extra power rails.
not exactly. there are various ways to apply power to a transistor to build a noise source. I was trained by some EE people on this forum that the flattest frequency response of a single diode junction happens below 5v. this is because of the physics of the different types of noise that dominate at different voltage potentials.

here is a more academic look at things although this is mainly just an overview

http://www.eng.auburn.edu/~wilambm/pap/ ... 7_C011.pdf
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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Tue May 05, 2020 9:13 am

Boss Dr-110 uses Shift registers as well... But is a little more simple... Uses 1 IC less, and the 110 can be battery powered (from 6v)...
Haven't tried myself though.
here is a more academic look at things although this is mainly just an overview
http://www.eng.auburn.edu/~wilambm/pap/ ... 7_C011.pdf
I'll going to read that now... If it is simple enough for me to understand. Cheers.


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Re: Simple white noise circuit with 5V? SN76489 ?

Post by socom93 » Tue May 05, 2020 9:30 am

BartBral wrote:
Tue May 05, 2020 8:38 am
socom93 wrote:
Tue May 05, 2020 4:41 am
Yekuku wrote:
Mon May 04, 2020 1:47 pm
I have checked the schematics and it is powered from 9V, the 40106 can run from 3V to 18V, so it is worth trying , the problem is that I dont have any 40106 lying around and due to the quarantine I cant get any soon.
That's a good choice, the 40106 can easily work with 5V, you should check the noise source schematic from an 808 hihats.
Uhhhmmm, have you seen the TR-808 schematics? It is actually Transistors in the noise-generator. I think you mean the TR-909 instead. That uses 4006 shift registers.
https://www.ti.com/lit/ds/symlink/cd400 ... 8685754789
Sorry, I was thinking of what Eric Archer did for his 808-inspired Hihats, creating noise using hex-inverters only, no transistor involved and working perfectly at 5V.

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Tue May 05, 2020 9:33 am

Please don't apologize! I have my facts mixed up on a regular basis!
I was just a bit confused... So I checked to see.

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by Yekuku » Tue May 05, 2020 12:14 pm

Well I got more than I was looking for, thank you very much for your input folks, this is educating.
Just for the record, i had a 7414 Hex Inverter Schmitt Trigger in my drawer and tried the 40106 noise circuit but i got no luck, it produced some kind of noise but nothing close to white noise.
Currently I am trying to educate myself by studying noise in semiconductors and shift registers :hmm:
I will let you know about how this goes :)

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by J3RK » Tue May 05, 2020 12:24 pm

This MIGHT work at 5V. It will need some resistor tweaks to get the signal high enough though for sure. I use this as a sample-source for my shift register based designs. Changing the 1.5M and 4.99K resistor can boost the noise a bit. I tweak the resistors until I get around 2V P2P which is sufficient to sample noise for the shift register, but is pretty quiet for audio use. Might need to boost gain with an op amp circuit for audio use.

Attached is a PDF of my newest Bit Station circuit which includes a shift register, if you want to take a look at it.
WhiteNoise.PNG
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Last edited by J3RK on Tue May 05, 2020 12:27 pm, edited 2 times in total.
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Re: Simple white noise circuit with 5V? SN76489 ?

Post by guest » Tue May 05, 2020 12:25 pm

yeah, the schmitt trigger noise sources make some good "noise", but its not white noise. i like the sound for some things and not others. ive seen them a lot in hihat circuits. the shift register/microcontroller can make some very good white noise, and it can also make some very interesting pseudo noise if clocked at a lower rate. a diode/transistor noise circuit is very good as well, but be sure to filter out the powersupply. they tend to use high gain circuits, and mains hum can dominate over the white noise. in a pinch, ive used resistor noise as well. you need to follow that with a lot of AC coupled opamp stages.
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Re: Simple white noise circuit with 5V? SN76489 ?

Post by jorg » Tue May 05, 2020 3:12 pm

CD4000 CMOS runs just fine on +5V; no special power supplies needed - the TR-909 circuit would fit the basic requirements here.
I have generated noise using a CMOS inverter biased to the linear region (DC feedback but eliminate as much AC from the feedback as possible for high gain).
Also, Electric Druid Pentanoise might be of interest. You don't have to DIY the chip itself; your whole circuit is DIY. :-)

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Tue May 05, 2020 10:14 pm

jorg wrote:
Tue May 05, 2020 3:12 pm
Also, Electric Druid Pentanoise might be of interest. You don't have to DIY the chip itself; your whole circuit is DIY. :-)
I was wondering myself... would it be possible to twist the NOISE2 code into spitting out for example 2xpink and 2xwhite?

Just wondering...

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by Synthiq » Wed May 06, 2020 3:45 pm

BartBral wrote:
Tue May 05, 2020 10:14 pm
jorg wrote:
Tue May 05, 2020 3:12 pm
Also, Electric Druid Pentanoise might be of interest. You don't have to DIY the chip itself; your whole circuit is DIY. :-)
I was wondering myself... would it be possible to twist the NOISE2 code into spitting out for example 2xpink and 2xwhite?

Just wondering...
It is possible but at a lower sample rate since you have to execute more instructions per sample. The pink noise uses the 5-bit DAC as output. There is only one DAC so the second output has to be different but I used a 4-bit PWM with good results so that can be solved.

But the real question is how much time you want to spend on code changes to save $0.73 for a second chip for the additional outputs.

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by JimY » Thu May 07, 2020 3:18 am

Image
In this plan, 3 unused inverters are wired input to output. This is intended to stop them from making any uncontrolled interference. It should be done - but not that way. Simply wire an unused input pin to 0v and leave its output disconnected.
As you only need 3 Schmitt inverters, you can also use 4093 Nand gates with one of the 2 inputs tied to V+.
TTL devices would need to be from the 74HC or HCT ranges such as 74HC14.

Another strategy is to use a charge pump chip to generate 10v and try the transistor Zener noise circuit.
Image

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Thu May 07, 2020 10:59 am

Synthiq wrote:
Wed May 06, 2020 3:45 pm
BartBral wrote:
Tue May 05, 2020 10:14 pm
jorg wrote:
Tue May 05, 2020 3:12 pm
Also, Electric Druid Pentanoise might be of interest. You don't have to DIY the chip itself; your whole circuit is DIY. :-)
I was wondering myself... would it be possible to twist the NOISE2 code into spitting out for example 2xpink and 2xwhite?

Just wondering...
It is possible but at a lower sample rate since you have to execute more instructions per sample. The pink noise uses the 5-bit DAC as output. There is only one DAC so the second output has to be different but I used a 4-bit PWM with good results so that can be solved.

But the real question is how much time you want to spend on code changes to save $0.73 for a second chip for the additional outputs.
Thanks for that!

And yes, I think it would be much easier to just buy another PIC. Otherwise I would have to learn how to program PIC-assembler... And I think that'll take a few(hundred) hours for me. ;)
Cheers!

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Re: Simple white noise circuit with 5V? SN76489 ?

Post by Yekuku » Thu May 07, 2020 12:52 pm

thank you all for your input, here is an update:
I found a 40106 and tested the circuit, it works with 5v , sounds like white noise and it looks like pulse bursts (using an oscilloscope).
I tried to fine tune using the pot to get the best results, I am attaching a sample , if anybody is interested to check it out.
I am trying the transistor open collector and the transistor + zener circuits, but i am not having any results with 5V.
I havent tried anything with shift registers yet, I will inform you as soon as I do.
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Re: Simple white noise circuit with 5V? SN76489 ?

Post by BartBral » Thu May 07, 2020 1:21 pm

Think that'll do, won't it?...
There are some frequencies that are a bit over-represented, and others a little less... but it sounds like white-noise to me.
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Re: Simple white noise circuit with 5V? SN76489 ?

Post by Yekuku » Thu May 07, 2020 3:31 pm

Thanks for the spectrograph BartBral, much appreciated.
By turning the pot you get tuned "dial up modem" noise, I tried to adjust it so that the "tuned" portion of the sound is masked under the noise.
This sample was taken from a CD40106, an interesting fact is that different brands of 40106s , do not sound the same.
An NXP HEF 40106 sounded more screamy compared to a TI CD40106.
A 74HC14 did not produce noise.
I will try to ground the unused input pins as Jimy suggested and I will report back.

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