Difference between revisions of "Noise Generator on ER-PROTO-01"
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* Voltage Gain = 148 | * Voltage Gain = 148 | ||
* Switched from TL074 to TL084 | * Switched from TL074 to TL084 | ||
| − | |||
[[file:ER-PROTO-01_NOISE_WHITE_Before.PNG]] | [[file:ER-PROTO-01_NOISE_WHITE_Before.PNG]] | ||
| + | * Output seems pretty quiet (~200 mV) | ||
| + | ** Issue is 2N3904 is much quieter than a BC548 | ||
* Offset errors = about 500 mV | * Offset errors = about 500 mV | ||
** Gain = 148, 500mV = 3.5mV offset voltage | ** Gain = 148, 500mV = 3.5mV offset voltage | ||
| Line 50: | Line 51: | ||
[[file:OpAmp_Offset_Adj.PNG]] | [[file:OpAmp_Offset_Adj.PNG]] | ||
| − | * | + | * With offset |
[[file:ER-PROTO-01_NOISE_WHITE.PNG]] | [[file:ER-PROTO-01_NOISE_WHITE.PNG]] | ||
| Line 74: | Line 75: | ||
[[file:FFT_White_Noise_25KHz.PNG]] | [[file:FFT_White_Noise_25KHz.PNG]] | ||
| − | |||
| − | |||
=== Blue Noise Generator === | === Blue Noise Generator === | ||
Revision as of 14:32, 31 January 2023
Contents
Features
- Eurorack 6HP, 3U module
- Noise Generator
- Based on Moritz Klein's Designing a white, pink & blue noise generator from scratch design
- 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
- Noise Generator
- White/Pink/Blue noise
- High Pass Filter (Blue Noise)
- Low Pass Filter (Pink Noise)
Build
White Noise Generator
- Voltage Gain = 148
- Switched from TL074 to TL084
- Output seems pretty quiet (~200 mV)
- Issue is 2N3904 is much quieter than a BC548
- Offset errors = about 500 mV
- Gain = 148, 500mV = 3.5mV offset voltage
- Add offset voltage trimmer
- Circuit from here
- With offset
- White Noise Scope capture
- 100 mS / div
- 5 mS / div
- 200 uS / div
- 20 uS / div
- FFT, 25HKz range
Blue Noise Generator
- FFT 1mS scope setting
- Amplitude is too small
- Added amplifier to the output stage
Pink Noise Generator
Jacks
Connectors
J1 - White Output
- +/- 7.5V swing
J3 - Pink Output
J4 - Blue Output
Eurorack Power
Build
On Controls Card
- Install J1, J3, J4
- Wire J1-S to J3-S
- Wire J3-S to J4-S
On Daughtercard
- Transistor Noise Source wiring
- Opamp wiring
- Wire J38-3 or J38-5 to nearby GND
- Install U1 14 pin socket near "middle of card
- Pin 4 goes towards +12V
- Add 10 Ohm resistor U1-4 to +12V
- Add jumper U1-11 to GND
- Add jumper U1-8 to U1-9 (Blue loopback)
- Add jumper U1-6 to U1-7 (White loopback)
- Install R16 1K J1-8 to Open bus row (J1-T) - White noise out
- Install R15 1K J3-6 to Open bus row (J3-T) - Blue noise out
- Install R14 1K J4-4 to Open bus row (J4-T) - Pink noise out
- Install 100K from U1-13 to U1-14
- Install 22K from U1-13 to GND
- Add wire U1-8 to R15 (new row)
- Add wire U1-14 to R14 (new row)
- Add wire U1-7 to R16 (new row)
- Add wire U1-1 to U1-5 (NOISE_WB)
- Rest per schematic
Debug
- 60 Hz rail-to-rail noise on U1-1
- 60 Hz noise disappears when scope is plugged in to output
- Likely a "scope-ism" since it's not on the output
- Switched to BC548 - much more noise
- About 15x louder
