[AMRadio] advice on el cheapo elecret mics


k0ng at inebraska.com k0ng at inebraska.com
Wed Dec 13 20:17:51 EST 2006


Vince: If your electret contains the FET follower inside, the typical  
source impedence of the FET is about 1.5K to 3.0K Ohms. I usually AC  
couple the output
(with say a 1 uF cap observe polarity carefully) to a 5 to 10K load.

Usually anything from a 1.5 V battery to a 6 V battery or well filtered supply
will work (I usually put a few K Ohms in series with the supply.

If your supply lines are long, it is best to put a 1 uF cap and a .01 uF cap
across the electret supply input and ground.

They do love to hum so shield well.

Good Luch, Charlie,  K0NG

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