On Thu, 24 Apr 2008 09:22:53 -0700 (PDT), "Mr. Land"
wrote:

Greetings,

When in use, a few of our home theater components heat up the interior
spaces of our entertainment center to a temperature that I feel is too
hot (yes, that's a very subjective statement). The entertainment
center uses tall, mostly glass doors, and they are one-piece,
therefore when they are open they protrude pretty far into the room.
When they are closed, there is little-to-no ventilation inside the
cabinets. One evening, I mustered up some courage and tried simply
leaving the doors open but sure enough, one of my kids came close to
ripping the entire door off of its hinges when she bumped into it.


I encountered a similar heating problem when putting an LCD TV in a
cabinet. I came up a fix using a $3 PICAXE chip that is programmable
in BASIC and a $5 temperature sensor that gives the actual temperature
(in degrees C). The sensor is mounted above the hottest point of the
TV (nothing inside any component). It's powered by a "wall wart"
supply, so all the wiring is low voltage. The PICAXE programming
software is a free download from http://www.rev-ed.co.uk/picaxe/

http://www.picaxe.us/AV-fan.html

You can set the on and off temperatures (in the program code) to
whatever works best for you. A more sophisticated version would use
the PWM capability of the PICAXE chip to control fan speed, running
the fan(s) only fast enough to maintain an acceptable temperature
rise.

John