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How To Build A Condenser Microphone For Less Than $8
Joshua Casper on Sat, July 9th | 0 comments
If we told you that you could build your own omnidirectional condenser microphone for less than $8 in under 3 minutes you might not believe me. But you can! And Joshua Casper shows you how.

This Electret omnidirectional condenser microphone has a wide 30–15,000 Hz frequency response. You can build your own for less than $8 and in about 3 minutes. It will be a decent microphone. The same type used in many common electronics… and for the price and labor it really can’t be beat!

Parts List *prices taken from Radio Shack Online:

  • Electret Microphone Element with Leads - $3.99
  • 1 x 0.1uF 50V Hi-Q Ceramic Disc Capacitor (2-Pack) - $2.49
  • 1 x 2.2K ohms 1/2W 5% Carbon Film Resistor (5-Pack) - $1.49
  • Various connect wires. 

Tools List

  • 9V Battery with cap and connectors (*switch optional)
    • Note about the battery. Most Electret microphones can handle between 4 and 10 volts, make sure to double-check the specs on yours before you start.
  • Bread Board (also optional if you have alligator connector wires)
  • Amp (Learn how to build your own here)

Getting Started

This tutorial will use the amplifier circuit that I made as a tutorial here on Ask.Audio. That amplifier works well with this microphone circuit. It will occupy one half of a large breadboard while the small microphone circuit will take up a little bit of the other side.

I highly suggest following along and completing that tutorial before starting here, although there are many other ways to connect this microphone to other amps and speakers. 

Now, if you decide to use an amplifier that isn’t the one from my tutorial you will need to do some different/additional steps. 

For example, you will want to buy a mono audio plug that will fit into whichever amp you are using, if it doesn’t have its connectors exposed for alligator clips. Then you will need to solder, or otherwise, connect the negative and positive wires to the plug while leaving the other ends of the wires exposed in order to connect them to the breadboard. My “repairing headphones” tutorial may help you if you are not sure.

Step 1

Connect the positive and negative leads of the Electret Microphone Element to two columns on the bread board. 

NOTE: You probably bought an Electret that already has those leads, if you didn’t, don’t worry we can add our own. It will require a bit of soldering. 

If your Electret doesn’t have leads already attached, turn it around and look at the back. You will want to heat up those pads and add positive and negative wires. The negative pad has three metal spokes coming out of it that connects the pad to the outer case. 

Step 2 

Connect the negative of the mic to the ground rail of the breadboard using a jumper wire.

Step 3

Connect the positive (hot) mic lead to the power rail using the 2.2k Ohm resistor.

Step 4

Connect the positive and negative battery leads to their respective breadboard rails. 

Success! Now our microphone has the power that it needs to operate!! 

WARNING: If you have chosen not to connect/use a switch for your power source you should disconnect the battery at this time. Come back to this step after your power on your amp. If you do have a switch, make sure the power is off and only turn it on after the amp is powered. 

If you want to add a power LED indicator to the microphone circuit, follow step 2 of the Amp Tutorial.

Step 5

Connect the negative lead of the mic to the negative rail of the amp circuit using a long jumper. 

Step 6 

Connect the 0.1uF Capacitor from the positive mic lead’s column to a new column. Then connect the new column, the other side of the capacitor, to the right pin of the volume potentiometer of the amp circuit. 

For Other Amps

You will want to connect the mic’s negative to the negative lead wire and the 0.1 capacitor to the positive lead wire of the plug you prepared in the earlier steps. Then you just need to plug it into your amp. 

Step 7 

Turn the power on for the Amp first. Then turn the power on for the Microphone. Then speak, scream, rap or sing into your very first DIY condenser microphone!! 

 

And here's how the same microphone looks once Joshua Casper had made a few amendments, which admitedly pushed the total price over $8!

DIY desktop microphone

 

 

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