On May 26, 2011, at 6:32 PM, Jim Lowman wrote:
Please reply to jruing@ameritech.net
-------- Original Message --------
Subject: Model 715 question
Date: Wed, 25 May 2011 23:57:35 -0400
From: Richards <jruing@ameritech.net>
Mono ? Really ? Do HEIL microphones really use 1/8 inch mono
plugs ?
Not a three-pole jack like they use on popular computer microphones?
Like they have on the K3 ? How did this happen ?
So... Is there a way to use that jack with computer type electret
condenser microphones ? or with dynamic type computer headset
microphones ?
Can someone good at reading the schematic tell me if there is a way to
provide bias voltage to a STEREO three-pole jack (assuming I install
one in place of the MONO jack it comes with) to provide bias voltage
like is provided on Pin 2 of the Omni VII and Model 715 8-pin mic
connector? I am still trying to figure these things out.
Dynamic microphones do not need any DC bias, so they just connect to
tip and ring, the two connectors on the 1/8 inch jack.
HT's such as Icon use a stereo plug with the middle connector having a
small DC voltage on it. It is current limited so that if it is shorted
to ground by placing a mono plug in the jack, nothing happens except
for a few milliamps going down the drain, as it were.
Computer headsets are more complicated, they have 3 connections like a
stereo microphone.
This was the first hit I found when I googled for "computer microphone
wiring":
<http://www.hobby-hour.com/electronics/computer_microphone.php>
As you can see, you need to install a voltage source and current
limiting resistor.
Note that using this may not be a good thing, try to get a headset
with limited high frequency response in the microphone and some echo
cancelation or you will be transmitting everything except the
operator's voice. :-(
73,
Geoff.
--
Geoffrey S. Mendelson, N3OWJ/4X1GM
It's amazing how many people have no clue what the word "contiguous"
means. :-(
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