View source for Noise Generator on ER-PROTO-01

[[File:tindie-mediums.png|link=https://www.tindie.com/products/28599/]]

[[file:ER-PROTO-01_NOISE_P1090103-FR-B-720px.jpg]]

== Features ==

* Eurorack 6HP, 3U module
* Noise Generator
** Based on Moritz Klein's [https://www.youtube.com/watch?v=0yB_h_wFkh4 Designing a white, pink & blue noise generator from scratch] design
** [https://en.wikipedia.org/wiki/Colors_of_noise White, Pink, Blue noise outputs]
** Outputs are all buffered
* Built on [[ER-PROTO-01]] card
* 10 pin Eurorack power connector

=== Noise Generator ===

* Credit Moritz Klein's Designing a white, pink & blue noise generator from scratch design

<video type="youtube">0yB_h_wFkh4</video>

* Noise Generator

[[file:moritz_noise.PNG]]

* White/Pink/Blue noise

[[file:moritz_WHITE_PINK_BLUE.PNG]]

* High Pass Filter (Blue Noise)

[[file:moritz_HPF.PNG]]

* Low Pass Filter (Pink Noise)

[[file:moritz_LPF.PNG]]

== Build ==

=== White Noise Generator ===

* Voltage Gain = 148
* Switched from TL074 to TL084

[[file:ER-PROTO-01_NOISE_WHITE_Before.PNG]]

* Output seems pretty quiet (~200 mV)
** Issue is 2N3904 is much quieter than a [https://www.mouser.com/ProductDetail/637-BC548B BC548]
** Switched to [https://www.mouser.com/ProductDetail/637-BC548B BC548]
* Offset errors = about 500 mV
** Gain = 148, 500mV = 3.5mV offset voltage
** Add offset voltage trimmer
** [https://electronics.stackexchange.com/questions/34071/how-do-i-correct-the-offset-voltage-of-op-amps-which-have-no-explicit-offset-nul Circuit from here]

[[file:OpAmp_Offset_Adj.PNG]]

* Schematic with offset

[[file:ER-PROTO-01_NOISE_WHITE.PNG]]

==== White Noise Scopecaps ====

* White Noise Scope capture
* 2 mS / div

[[file:White_Noise_Scope_Cap-01.png]]

* FFT, 25HKz range

[[file:FFT_White_Noise_25KHz.PNG]]

=== Blue Noise Generator ===

[[file:ER-PROTO-01_NOISE_BLUE.PNG]]

==== Blue Noise Screencaps ====

* FFT 1mS scope setting

[[file:FFT_Blue_J4_Noise_1mS.PNG]]

=== Pink Noise Generator ===

[[file:ER-PROTO-01_NOISE_PINK.PNG]]

=== Pink Noise Scopecaps ===

[[file:Pink_Noise_Scope_Cap.png]]

[[file:FFT_Pink_J4_Noise_1mS.PNG]]

=== Pink Noise LTSpice ===

[[file:ER-PROTO-01_NOISE_Pink_LTSpice.PNG]]

=== Jacks ===

[[file:ER-PROTO-01_NOISE_J38.PNG]]

== Connectors ==

=== J1 - White Output ===

* +/- 7.5V swing

=== J3 - Pink Output ===

=== J4 - Blue Output ===

=== Eurorack Power ===

[[file:ER-PROTO-01_U1_PWR.PNG]]

== Build Details ==

* Three card set
** [[ER-PROTO-01]] Front Panel card
** [[ER-PROTO-01]] Controls card
** [[ER-PROTO-01]] Daughtercard

[[file:ER-PROTO-01_NOISE_P1090115-720px.jpg]]

=== On Controls Card ===

[[file:ER-PROTO-01_NOISE_P1080760-JacksRework-720px.jpg]]

* Install J1, J3, J4
* Wire J1-S to J3-S
* Wire J3-S to J4-S

=== On Daughtercard ===

[[file:ER-PROTO-01_NOISE_P1090110-720px.jpg]]

* Transistor Noise Source wiring

[[file:ER-PROTO-01_NOISE_P1090111-720px.jpg]]

* Opamp wiring

[[file:ER-PROTO-01_NOISE_P1090112-ANNOTATED-720PX.jpg]]

== References ==

[https://www.schmitzbits.de/noise.html schmitzbits White Noise Source]