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