🚀 go-pugleaf

In article <829334769.18402@lodcomp.demon.co.uk>, Luke Jackson
<luke@lodcomp.demon.co.uk> writes
>Michael@zoec.demon.co.uk (Michael Clements) wrote:
>
>>Are there any techies who can say whether it is possible to use or
>>modify a standard UK telephone handset (not a mobile phone but the
>>plastic part you hold listen and talk into) on a conventional phone to
>>work with my Soundblaster 16 soundboard to replace the microphone &
>>speakers normally used when making internet phone contact.
>
>The problem is that the handsets that you normally use with sound
>cards have two pairs of wires, one for the microphone and the other
>for the speaker, whereas a phone line uses just one pair for both.  If
>the headset uses two pairs (while the phone itself uses one pair) it
>shouldn't be too hard to do a direct hookup?  I'm not sure if this is
>the case however.
>
Although a telephone itself has only two wires, the handset itself has
four - two for the microphone and two for the earpiece.  Traditionally
the microphone wires are blue and white and the earpiece wires are red
and green (if I remember correctly!).  You can quickly check by briefly
connecting a 1.5V cell (battery) across the red/green, when you should
hear a click in the earpiece.
-- 
Frank Erskine
Sunderland

Michael@zoec.demon.co.uk (Michael Clements) wrote:

>Are there any techies who can say whether it is possible to use or
>modify a standard UK telephone handset (not a mobile phone but the
>plastic part you hold listen and talk into) on a conventional phone to
>work with my Soundblaster 16 soundboard to replace the microphone &
>speakers normally used when making internet phone contact.

The problem is that the handsets that you normally use with sound
cards have two pairs of wires, one for the microphone and the other
for the speaker, whereas a phone line uses just one pair for both.  If
the headset uses two pairs (while the phone itself uses one pair) it
shouldn't be too hard to do a direct hookup?  I'm not sure if this is
the case however.

-- 
Luke Jackson

In article <1fT2sCAktsbxEwDR@g3wte.demon.co.uk>, Frank Erskine
<frank@g3wte.demon.co.uk> writes
>In article <829334769.18402@lodcomp.demon.co.uk>, Luke Jackson
><luke@lodcomp.demon.co.uk> writes
>>Michael@zoec.demon.co.uk (Michael Clements) wrote:
>>
>>>Are there any techies who can say whether it is possible to use or
>>>modify a standard UK telephone handset (not a mobile phone but the
>>>plastic part you hold listen and talk into) on a conventional phone to
>>>work with my Soundblaster 16 soundboard to replace the microphone &
>>>speakers normally used when making internet phone contact.
>>
Following up my last one - there IS another problem with a using a
telephone handset - the microphone needs a current source (around 30mA)
to energise it, because it's a carbon or amplified electret type...no
doubt someone will have ideas on how to do that simply!
-- 
Frank Erskine
Sunderland

On Fri, 12 Apr 1996 22:30:12 +0100, Frank Erskine
>Although a telephone itself has only two wires, the handset itself has
>four - two for the microphone and two for the earpiece.  Traditionally
>the microphone wires are blue and white and the earpiece wires are red
>and green (if I remember correctly!).  You can quickly check by briefly
>connecting a 1.5V cell (battery) across the red/green, when you should
>hear a click in the earpiece.
Thanks for this info. Do you happen to know whether there is any
reason why this should not work- for instance that the mic unit in a
standard handset has such a low output that the SB16 would be unable
to amplify it even at x8 gain setting to be of use or that the speaker
in the handset is incompatible in some way owing to its impedence.
Has anyone actually tried this mod yet?

--
Michael Clements

In article <31703a33.711113@news.demon.co.uk>, Michael Clements
<Michael@zoec.demon.co.uk> writes
>On Fri, 12 Apr 1996 22:30:12 +0100, Frank Erskine
>>Although a telephone itself has only two wires, the handset itself has
>>four - two for the microphone and two for the earpiece.  Traditionally
>>the microphone wires are blue and white and the earpiece wires are red
>>and green (if I remember correctly!).  You can quickly check by briefly
>>connecting a 1.5V cell (battery) across the red/green, when you should
>>hear a click in the earpiece.
>Thanks for this info. Do you happen to know whether there is any
>reason why this should not work- for instance that the mic unit in a
>standard handset has such a low output that the SB16 would be unable
>to amplify it even at x8 gain setting to be of use or that the speaker
>in the handset is incompatible in some way owing to its impedence.
>Has anyone actually tried this mod yet?
>
>--
>Michael Clements
As I said in my follow-up, you'd need a power supply to the microphone,
and with that you'd get a fairly high output.  If it's an *old-
fashioned* type handset you can perhaps fit another earpiece in place of
the microphone and that should work ok as a mike.
Regarding the impedance, I don't know how it'll match up to the SB!
Often the input impedance to an amplifier such as the SB is high, so
that it'll accept almost any input impedance.
Why not try it and see? :-)
-- 
Frank Erskine
Sunderland