Faith Freedom International

[everybee]

Speed up your computer.

http://tweakhomepc.virtualave.net/one/basics.shtml

[everybee]

Hum (50/60 cycle) cancelling on phone lines

I recently discovered something interesting. While playing around with a couple computers and connecting to the internet with a dialup modem (regular phone line) at one point I disconnected the phone cables in the house from the connection terminal block at the point where they come into the house (garage) to clean them. After cleaning the wires I connected only one of the cables going through the house to the phone line (the one going to the computer). After that I noticed that web surfing was a lot slower. I listened to the phone line through a telephone (computer not connected), pressed one button to clear the dial tone and noticed the sound of the 60 cycle hum on it. I thought that sounds as bad as the phone in my bed room (temporarily disconnected at this time). After thinking about hum bucking/boosting (canceling/reinforcing) ideas started going through my mind. I read some pages from the link above about the phone line and realized that the phone line going to the computer ran parallel to some electrical cables for about 20 ft (total length is about 100 ft from the garage to the computer) which isn't a good thing according the link above. I began to think about installing another line along a different route and even using shielded phone cable or maybe even high quality shielded audio cable. Then I got the idea of connecting the second cable (going to the bed room) that I left unconnected back onto the phone terminal in the garage along with the cable going to the computer and found that the hum was gone and the computer was a lot faster on the internet. With just the phone cable going to the computer connected the speed was about 16K to 19K (hum audible on telephone), but when I had both the computer phone cable and bed room phone cable connected at the telephone terminal block in the garage the computer connected at about 46K using a 56K modem (hum not audible on the telephone). So apparently the phone cable going to the bedroom must have picked up hum in opposite phase to the phone line going to the computer. This phenomenon is known as hum bucking.


Other examples of hum bucking/cancelling:

When I used to play around with vacuum tube audio electronics I tried making a hum balance control for various preamps. A hum balance control is basically a potentiometer connected across the filaments with the movable tap connected to ground or a positive DC voltage. Turning the potentiometer with the preamp on (and listening through an amplifier) can be used to balance and minimize or eliminate the hum. A positive (relative to the cathode) voltage is better since it prevents the filaments from emitting electrons. Also, hum bucking pickups are common on electric guitars. Balanced audio pick ups and audio cables are often used to eliminate hum, too.

[everybee]

You can check your connection speed by going to the link below, scrolling down to the bottom and entering your area code in the Bandwidth Meter.

http://reviews.cnet.com/2001-1_7-0.html