2 layers54 × 48.9 mm
Guitarpreamp
StoneRose35/cortexguitarfx
guitar effects processor implemented on various arm cortex platforms
49 parts146
2 layers85.1 × 62.2 mm
Mic extension board
StoneRose35/cortexguitarfx146guitar effects processor implemented on various arm cortex platforms
- Size
- 85.1 × 62.2 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 75
- Nets
- 73
- Pads
- 233
- Tracks, vias
- 357, 41
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 17 Aug 2022
- Updated
- 18 Oct 2026
Overview
Mic extension board is an open-source printed circuit board by StoneRose35, from the StoneRose35/cortexguitarfx repository on GitHub. It is a 2-layer board of 85.1 × 62.2 mm with 75 parts on 73 nets, routed with 357 tracks and 41 vias.
It is built around the ATMEGA88A-AU, NE5534D and TL072, with the 24LC128-I/P among its other parts. Its parts include 27 resistors, 11 capacitors, 10 connectors, 9 ICs and 8 diodes. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
4
ATMEGA88A-AU
TQFP-32(7x7)-40℃~+85℃ 1.8V~5.5V 10bit 1KB 20MHz 23 512Byte 8 Bit 8KB AVR Built-in FLASH TQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
NE5534D
SOIC-8-20V~-3V、3V~20V 0℃~+70℃ 1 1.5uA 100dB 10MHz 13V/us 3.5nV/√Hz@1kHz 300nA 38mA 4mA 4mV Built-in compensation SOIC-8 Operational Amplifier ROHSTexas InstrumentsOperational Amplifier
TL072
SOP-8-18V~18V 0℃~+70℃ 1.4mA 1.5nA 10V/us 10mV 2 2.5nA 3MHz 85dB SOP-8 Operational Amplifier ROHSGcoreOperational Amplifier
24LC128-I/P
PDIP-8-40℃~+85℃ 1,000,000 cycles 128Kbit 2.5V~5.5V 200 Years 400kHz 5ms Hardware write protection function、Noise suppression function I2C PDIP-8 EEPROM ROHSMicrochip TechnologyEEPROM
README
README.mdcortexguitarfx
guitar effects processor implemented on various arm cortex platforms Contains the following hardware elements:
- ARM Cortex M Microprocessor
- I2S Interface
- Three potentiometers
- SSD1306-based 128x64 Pixel OLED Display
- Two pushbuttons: 'Enter' and 'Exit'
- rotary encoder
- analog pre- and postprocessor: guitar preamp and postgain amp
Parts
75| Qty | Value | Footprint | References |
|---|---|---|---|
| 10 | 10k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R9, R17, R19, R21, R22, R24, R25, R26, R27, R28 |
| 8 | 22k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2, R3, R4, R15, R16, R18, R29 |
| 6 | 180 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R7, R8, R11, R12, R13, R14 |
| 6 | LED | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | D2, D3, D4, D5, D6, D7 |
| 3 | 4k7 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R5, R20, R23 |
| 3 | MountingHole | MountingHole:MountingHole_3.2mm_M3 | H1, H2, H3 |
| 3 | TestPoint | TestPoint:TestPoint_Pad_D1.5mm | TP1, TP2, TP3 |
| 3 | XLR3 | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J1, J7, J8 |
| 2 | 0.33uF | Capacitor_SMD:CP_Elec_4x4.5 | C8, C10 |
| 2 | 1N4001 | Diode_THT:D_DO-41_SOD81_P10.16mm_Horizontal | D1, D8 |
| 2 | 220uF | Capacitor_SMD:CP_Elec_6.3x7.7 | C2, C3 |
| 2 | 22uF | Capacitor_SMD:CP_Elec_4x4.5 | C13, C14 |
| 2 | 330uF | Capacitor_SMD:CP_Elec_6.3x7.7 | C11, C12 |
| 1 | 100k | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | RV1 |
| 1 | 1uF | Capacitor_SMD:CP_Elec_4x4.5 | C9 |
| 1 | 2.2uF | Capacitor_SMD:CP_Elec_4x4.5 | C15 |
| 1 | 24LC128 | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U6 |
| 1 | 33pF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1 |
| 1 | 6Pin ISP | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J5 |
| 1 | APE8865N-33-HF-3 | Package_TO_SOT_SMD:SOT-23 | U3 |
| 1 | ATmega88A-A | Package_QFP:TQFP-32_7x7mm_P0.8mm | U5 |
| 1 | Aux In | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J3 |
| 1 | Conn_01x01_Male | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | J10 |
| 1 | Conn_01x02_Male | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J2 |
| 1 | Conn_01x03_Female | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J9 |
| 1 | I2C Bus | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J4 |
| 1 | Input/Output | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J6 |
| 1 | LM4881M/NOPB | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U10 |
| 1 | MC78M05_TO252 | Package_TO_SOT_SMD:TO-252-2 | U7 |
| 1 | MC79M08_TO252 | Package_TO_SOT_SMD:TO-252-2 | U8 |
| 1 | NE5534 | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U4 |
| 1 | Stompbutton 1 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | SW1 |
| 1 | Stompbutton 2 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | SW2 |
| 1 | Stompbutton 3 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | SW3 |
| 1 | TL072 | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U2 |
| 1 | TL074 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | U1 |
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Questions
How big is the Mic extension board PCB?
It measures 85.1 × 62.2 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Mic extension board use?
75 parts, built around the ATMEGA88A-AU, NE5534D, TL072 and 24LC128-I/P. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Mic extension board KiCad files?
From the StoneRose35/cortexguitarfx repository on GitHub, at the commit this page was made from: the board is schematics/mic_extension_board/mic_extension_board.kicad_pcb and its schematic schematics/guitarpreamp/guitarpreamp.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Mic extension board design in my own project?
Its repository states no licence, so its author keeps all rights: ask StoneRose35 before reusing the design.