Instructables
Picture of Condenser Microphone Power Supply
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Condenser Microphones typically sound better than dynamic microphones. If you are unfamiliar with these two types of microphones you may want to read about them in this Wikipedia article.

 

http://en.wikipedia.org/wiki/Microphones#Condenser_microphone

The short version is this:

Dynamic microphones have a coil and a magnet. So they act like little electric generators. They do not require external power such as a battery to operate.

Electret condenser microphones have to little plates (capacitor), one of which vibrates in the presence of sound. The varying capacitance is turned into an electrical audio signal by a tiny built in pre-amplifier. So this type of microphone needs an electric current to operate. Besides sounding good, condenser microphones typically have better sensitivity. Also condenser microphone elements are typically smaller than the dynamic type and many condenser microphone elements are very inexpensive.

If you have been thinking about experimenting with condenser microphone elements I would suggest this one:

http://www.radioshack.com/product/index.jsp?productId=2062215

As of today it is only $2.89.

I have an extra mic that is still in the package. On the back it has a tiny graph of the frequency response. If you go to the Shure microphone web site, you can look at the specs for there very popular SM58 microphone, The RadioShack mic’s upper frequency response actually looks flatter than the SM58 out to about 15 Khz. It would be helpful if the Radio shack graph  had more resolution so we would know exactly where the upper frequency cut off actually is. It is actually well above the 10 Khz stated in the specs on the back of the package. Don’t get me wrong. The SM58 is a great microphone for live performances where the performer is belting out a tune with the mic almost touching their face. SM58s are really rugged. If you like to swing your microphone around by it’s mic cord and occasionally dropping it on the stage (Roger Daltrey) this is the microphone for you. I own two SM57s (same mic with a smaller wind screen). It just isn’t the right microphone for some applications such as DIY audio projects. By the way. The SM58 will set you back about $100. The RadioShack mic is an ok vocal mic but a really good area mic. If you want to use it as a vocal mic you will need a foam wind screen.

Some audio equipment provides voltage at the microphone input jack so an external power supply is not needed for a condenser mic. Some equipment does not. Many off the shelf condenser microphones (complete microphone including and audio cable and connector or a connector that accepts a microphone cable) have a built in battery holder to power the microphone and some do not. So sometimes, depending on what condenser microphone you are using and what you are plugging into, you need a battery operated power supply or it will not work.

Here is one fun microphone project I did a long time ago which is one of the reasons why I made my first condenser microphone power supply. We used to feed our outdoor pets which were the wild birds. To add to the experience I wired up one of the radio shack mics onto a shielded audio cable and ran the other end into the house by closing the window on the cable (you can do this with a thin cable. The other end of the cable plugged into the power supply. The output of the power supply plugged into a battery operated audio amplifier. The microphone was attached to the underside of the covered patio roof and the food dish was on the patio, 8 feet below. We could hear all the tweeting as if we were outside next to the dish. We could also hear their little beaks tapping the bottom of the plastic dish. From time to time we could hear possums rustling around outside after dark and of course crickets. On a good night it was like camping out under the stars in the living room.




 

 
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