On Fri, 15 Aug 2008 08:04:31 +0100, David Woolley (E.L) wrote: >Condenser microphones, that were historically used as broadcast >microphones,
Condenser mics have historically been used for MUSIC, both recording and broadcast (and they still are). Most broadcasters use dynamic mics for speech. Most US broadcasters wouldn't know a condenser mic if it bit them you know where. >do need a high voltage bias to generate their electrostatic >field. Electret transducers work on the same basic principle, but > gettheir field from the electret. Electret condenser mics need a different form of bias. The capsule (the transducer) is permanantly biased when it is manufactured -- it doesn't need anything from the circuitry. The very small signal produced by the capsule is amplified, usually by a FET follower circuit. This amplifier circuit is what needs DC voltage and current from the radio. >Electret "bias" voltages are far too >small to be used directly to provide the field in the microphone. See above. 73, Jim K9YC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
