Low noise Mini Electret Microphone PreAmplifier

  • Rajkumar Sharma
  • 40.308 Views
  • easy
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  • SKU: EL51787
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This single supply microphone pre-amplifier amplifies the output signal of an electret capsule microphone to audio line levels. An op-amp is used as a trans-impedance amplifier to convert the output current from the microphone into a signal-level voltage. The circuit works with 9V so it is a good choice for battery-operated systems.

Features

  • Supply 9V DC
  • Current Approx. 3mA
  • On-Board Microphone
  • Very thin and narrow PCB

Schematic

Parts List

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Version v.2 with LV321

This v.2 of the above-board provides an additional option to use LV321 OPAMP in case you can’t find the OPA172. The board has two OPAMP footprints, and you should solder only one. If you use LV321 OPAMP, then the maximum input Vcc=5Vdc. If you use OPA172 OPAMP, then the maximum input Vcc=36Vdc.

Photos

img_5974

Video

OPA172 Datasheet

opa172

PCB

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JensJ

Thank you for this. Modified it to run on a 5V supply and using another OP-Amp and it works perfectly with those alterations.

Dan Gonzalez

the capacitor C5 is well polarized in the diagram, or is it a misprint

kenahilton

I want to purchase the above microphone preamp. What is the cost in USD and how do I get it?

Javier

Hi! Is it possible to hear some real sound tests? is it possible to get a copy of this mounted for experimental purposes? thanks and good job!! 🙂

Phil Stewart

Hi,
I’m interested in several of these — more if they perform well.
How is performance in the presence of RF interference & nearby electrical devices? The PC board is pretty basic — does it require shielding?
I am interested in either the PC board or assembled device, depending on price. Thanks!

Simon Rung

Hi!
How much for an assembled device?
For now I’m in a prototyping face and i would like to try one of these out.

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