99 lines
4.8 KiB
Plaintext
99 lines
4.8 KiB
Plaintext
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HOW TO CONNECT A CELLFONE TO A MODEM
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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MODEM
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T1 | | T2
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pin 1 o--||--o___ ______o o______ ___o--||--o pin 6
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|<7C>| |<7C>|
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|<7C>| 1b 2b |<7C>|
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|<7C>|___________________|<7C>|
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1a |<7C> _____ ____________ <20>| 2a
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|<7C>| \/ |<7C>|
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|<7C>| 1c /\ 2c |<7C>|
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pin 24 o__________|<7C>|___/ \__/\/\/\___|<7C>|_________o pin 24
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1K
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preset
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adjusted to give best
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tx/rx isolation
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To connect a modem to a motorola 4800.
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You need :-
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2 off 2.2uF capacitors. (non polarized)
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2 off isolation transformers (signal) with 3 seperate windings
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1 off 1k ohm preset
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1 off BT socket (to plug modem into)
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Using a capacitor to provide DC isolation, connect winding (a) of transformer
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1 to pin 24 on D plug and the other end of winding (a) to pin 1 of the D plug
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via a capacitor.
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Connect winding (a) of transformer 2 in a similar manner to pins 24 & 6.
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(see above).
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Winding 1(b) & 2(b) are connected as in above picture, the start of each winding
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goes to the BT socket (pins 2 & 5), and the two ends connect to each other.
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Winding 1(c) & 2(c) are connected as in picture, the start of winding 1(c) is
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connected to the end of winding 2(c), and 2(c) start is connected via a 1k
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preset to the end of 1(c).
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The way it werks is thus.
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A signal being presented to winding 1(a) will appear on both 1(b) and 1(c).
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it will then couple to transformer 2 through 2(b) and 2(c), BUT because
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winding (c) is connected out of phase, it will cancel out the signal induced
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by winding (b) thus giving no signal at 2(a).
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A signal from 2(a) will follow the same proceedure and not appear at 1(a),
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but a signal at either 1(a) or 2(a) will be present at the modem. (actually
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only 50% of the signal will reach the modem, the other 50% is eaten up by
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the balancing resistor.
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The signal from the modem is delivered to both 1(a) & 2(a), (50% of signal
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is present at both ports), but as pin 1 is the microphone input to the fone
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it will accept the signal and send it on its way. Pin 6 on the other hand
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is the received audio, and it don't care if there is a signal connected to
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it or not as it is an output.
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The pin numbers given are for the Motorola 45/48/6800 mobile/transportable,
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but the basic idea should werk on any cellfone. It is also a good idea to
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disable the microphone and earpiece in the handset once the modem is
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connected, otherwise (a) the noise from the earpiece gets on your tits, and
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(b) the microphone tends to pick up your 100 gigawatt stereo system and send
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the output of same to the remote modem, this causes transmission errors as
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remote modems don't appreciate or understand 'techno techno techno', at high
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volume levels.
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<20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͻ
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<20> WRITTEN AND UPLOADED BY <20>
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<20> DaveX <20>
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<20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ
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modified version for better cps
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MODEM
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T1 | | T2
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pin 1 o--||-, ,--o___ ______o o______ ___o-, ,---||--o pin 6
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| / |<7C>| |<7C>| \ |
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| \ |<7C>| 1b 2b |<7C>| / |
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|___ / |<7C>|___________________|<7C>| \___|
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2.2K preset\ 1a |<7C> _____ ____________ <20>| 2a / 2.2K preset
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/ |<7C>| \/ |<7C>| \
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\ |<7C>| 1c /\ 2c |<7C>| /
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pin 24 o____|______|<7C>|___/ \__/\/\/\___|<7C>|_____|____o pin 24
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2.2K
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preset
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adjusted to give best
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tx/rx isolation
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Set all presets to mid position, LOCK MODEM TO 12000 BAUD or 9600 if you
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not got 12,000 and connect to a USR modem somewhere. Keep adjusting both
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recieve and transmit presets untill max cps is achieved. (boring, time
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consuming, fiddly, a real pain in the arse. but worth it.)
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Make sure you set fone volume to max before making adjustments or next time
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you try and use it, the settings will be wrong.
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**************************************************
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