Phuk Magazine Issue 01 Phile 06 of 10

Published in

· 5 years ago

  

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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 

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