Microphone preamp

polykit·microphone-preamp

Microphone preamp PCB layout, top view — open source board by polykit

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About the Microphone preamp PCB

Microphone preamp is an open source PCB design by polykit, published on GitHub. It is a 2-layer board measuring 47.5 × 67.5 mm, with 34 components from 22 distinct parts.

Other key parts include the INA217 and TL071. By type, the board carries 11 resistors, 10 capacitors, 7 connectors, 4 diodes and 2 ICs.

It belongs with the audio and power & battery designs in this gallery.

From the project

Schematics and PCB for a microphone preamp with phantom power

This repository contains schematics and PCB of a microphone preamp with switchable phantom power. It is based on the INA217 low-noise instrumentation amplifier. An additional buck-boost converter is needed for a phantom power higher than 12V.

\* LED current limiting resistor, change value according to used phantom power, 10k is for 48V

\*** adjust to change max. gain, smaller is more gain

Microphone preamp, from the project README — From the project README

Main components on the Microphone preamp

Microphone preamp bill of materials (BOM)

34 components, 22 distinct parts.

Qty	Part	Footprint	Refs
1	INA217	DIP-8_W7.62mm_Socket_LongPads	U1
1	TL071	DIP-8_W7.62mm_Socket_LongPads	U2
1	LED	Molex_KK-254_AE-6410-02A_1x02_P2.54mm_Vertical	J1
1	PHANTOM POWER	Molex_KK-254_AE-6410-03A_1x03_P2.54mm_Vertical	J2
1	MIC XLR	Molex_KK-254_AE-6410-03A_1x03_P2.54mm_Vertical	J3
1	PHANTOM POWER SW	Molex_KK-254_AE-6410-03A_1x03_P2.54mm_Vertical	J4
1	GAIN 10k	Molex_KK-254_AE-6410-02A_1x02_P2.54mm_Vertical	J5
1	OUT	Molex_KK-254_AE-6410-02A_1x02_P2.54mm_Vertical	J6
1	POWER	IDC-Header_2x05_P2.54mm_Vertical	J7
4	1N4148	D_DO-35_SOD27_P7.62mm_Horizontal	D1, D2, D3, D4
5	100n	C_Disc_D3.0mm_W2.0mm_P2.50mm	C1, C3, C6, C7, C8
1	47u/50	CP_Radial_D6.3mm_P2.50mm	C2
2	47u/50**	C_Radial_D10.0mm_H12.5mm_P5.00mm	C4, C5
2	10u	CP_Radial_D5.0mm_P2.50mm	C9, C10
1	10k*	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R1
2	6k8	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R2, R3
1	47k	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R4
2	2k2	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R5, R6
1	100***	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R7
1	1M	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R8

Show 2 more

Qty	Part	Footprint	Refs
1	1k	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R9
2	10	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R10, R11

Microphone preamp design files

The KiCad project lives in the polykit/microphone-preamp repository on GitHub; these links point at the commit this page was built from.

Layoutmicrophone-preamp.kicad_pcb

Microphone preamp: common questions

How big is the Microphone preamp PCB?

The Microphone preamp measures 47.5 × 67.5 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Microphone preamp?

34 components, from 22 distinct parts. The full bill of materials is listed on this page.

Where can I download the Microphone preamp design files?

From the polykit/microphone-preamp repository on GitHub, which has the KiCad layout; the links under Design files point to each one.

Can I use the Microphone preamp design in my own project?

The repository has no license, so all rights stay with polykit. Use it as a reference, and ask the author before reusing the design.

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