63 lines
2.2 KiB
Plaintext
63 lines
2.2 KiB
Plaintext
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PHUK MAGAZINE - Phile 6 of 10
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=============================================================================
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-----------------------------
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Simple Line Monitor - TheGoat
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-----------------------------
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The simple line monitor provides a number of functions, initialy it
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was produced to give a visual indication of ringing.
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Parts : Line connection jack & cable.
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Two led's, green and red.
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Two resistors 33K.
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Small piece of vero.
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For convenience I used a ready molded phone jack cable scavenged from
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an old phone, I also found it had a .1" pin socket on the other end,
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the plug for which was also removeable from the phone, mounting the
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plug at one end of the vero, I put the resistors and LEDs in the
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middle to form a small square.
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1 +----------------------+
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2 +------\ +----+ ==+2-\-R1----D1+----+ |
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3/4 |P/jack]+----//--| + ==+ \--R2----+D2--+ |
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5 +------/ +----+ ==+5----------------+ |
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6 +----------------------+
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Effectivly, pin 2 of the phone jack connects to both resistors each
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resistor to a diode, note positive of each diode. and finaly both
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diode ends lead back to pin 5 of the phone jack.
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Pin 2 ------------------+-------+
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R1 R2
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+ |
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D1 D2
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Pin 5 ------------------+-------+
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The connection of pin 5 and 2 is not too important.
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When connected to a line one LED will be lit to show line voltage,
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if a ring signal is present both LEDs will light brightly in the ring
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pattern. (ie: flash-flash--blank-blank-..... etc). As such this met
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the initial requirements, but when we first tried it in anger we
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found it could also indicate a number of other things. When a phone
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is also attached to the line and is picked up the single LED will dim
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to about half its previous brightness. If a futher phone is added,
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then when the second phone is picked up a futher dimming is noticable.
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When tapping a line, indication that the destination phone is in use is
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important.
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Coming in the next article: Upgrading to give a direct connection to
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a computer port for Ring Indication.
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- TheGoat
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+++
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EOF |