Quad white and colored noise source. Quad random voltage source

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Haralds:Werk
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Quad white and colored noise source. Quad random voltage source

Post by Haralds:Werk » Wed Jun 24, 2020 5:30 am

It is quite useful to have different adjustable noise and random voltage sources. Depending on your patch stile of course. Here is the quad version of my noise module from the NGF project. It is a combination of two original Elektor Formant modules. The noise module from Elektor Formant book one and the colored noise (CNC) module from book two. It provides four independent white noise outputs, four adjustable colored noise outputs with "red" "blue" adjustment. The four random voltage outputs are adjustable in speed of change. The noise is derived from the reverse biased BE diode of an NPN transistor.

Specs and features
• Four independent white noise outputs
• Four independent adjustable colored noise outputs with "red" "blue" adjustment
• Four random voltage outputs, adjustable in speed of change
• Four LED indicating the random voltage change
• Runs on +/-12V and +/-15V
• Power consumption around 65mA each rail

The documentation and the Gerber files for download can be found in my website.


Quad_Noise_front.JPG
Quad_Noise_F_101_schematic.png
Quad_Noise_B_090_schematic.png
Quad_Noise_side.JPG
Quad_Noise_F_PCB.JPG
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dot matrix madness
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Re: Quad white and colored noise source. Quad random voltage source

Post by dot matrix madness » Wed Jun 24, 2020 6:32 am

Any recommendation, which transistors to consider as candidates in the noise source? BC547C, 2N3904
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Re: Quad white and colored noise source. Quad random voltage source

Post by jorg » Wed Jun 24, 2020 9:50 am

Separate (non-correlated) noise junctions?

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Re: Quad white and colored noise source. Quad random voltage source

Post by Haralds:Werk » Wed Jun 24, 2020 1:14 pm

dot matrix madness wrote:
Wed Jun 24, 2020 6:32 am
Any recommendation, which transistors to consider as candidates in the noise source? BC547C, 2N3904
No, I randomly picked up four BC550C. One of them was a bit at the weak side, but this is easily compensated with increasing the amplification.
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Haralds:Werk
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Re: Quad white and colored noise source. Quad random voltage source

Post by Haralds:Werk » Wed Jun 24, 2020 1:15 pm

jorg wrote:
Wed Jun 24, 2020 9:50 am
Separate (non-correlated) noise junctions?
Yes, four independent noise sources.
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EATyourGUITAR
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Re: Quad white and colored noise source. Quad random voltage source

Post by EATyourGUITAR » Thu Jun 25, 2020 12:55 pm

A noise bridge circuits clips in the transistor. If you always use noise bridge circuits in parallel, they should be pretty close in amplitude. There is enough gain that you could use anything as a noise source at the input of the noise bridge.

I took a look at the schematic. It looks like it already has enough gain. You can give it more gain by adjusting resistor values. You could add a single transistor to amplify the noise source. You would need to cut one trace per channel. You would need to mount 4 transistors 8 resistors. Probably just change the 10K into 2M. 5K should work better.
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Haralds:Werk
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Re: Quad white and colored noise source. Quad random voltage source

Post by Haralds:Werk » Sun Aug 02, 2020 4:46 am

EATyourGUITAR wrote:
Thu Jun 25, 2020 12:55 pm

I took a look at the schematic. It looks like it already has enough gain. You can give it more gain by adjusting resistor values. You could add a single transistor to amplify the noise source. You would need to cut one trace per channel. You would need to mount 4 transistors 8 resistors. Probably just change the 10K into 2M. 5K should work better.
I did not understand. Why should I change a perfectly working module?
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Re: Quad white and colored noise source. Quad random voltage source

Post by EATyourGUITAR » Sun Aug 02, 2020 8:24 am

Haralds:Werk wrote:
Wed Jun 24, 2020 1:14 pm
dot matrix madness wrote:
Wed Jun 24, 2020 6:32 am
Any recommendation, which transistors to consider as candidates in the noise source? BC547C, 2N3904
No, I randomly picked up four BC550C. One of them was a bit at the weak side, but this is easily compensated with increasing the amplification.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

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Re: Quad white and colored noise source. Quad random voltage source

Post by Haralds:Werk » Wed Aug 05, 2020 8:56 am

Ahh yes, but this point is already addressed in the building hints. There is only one resistor value to change.
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