[MLB-WIRELESS] Voltage Regulator-- 12v to 9v

Andy Freeman Andy.Freeman at jc.com.au
Tue Mar 12 14:30:52 EST 2002


The question was asked...

"how do I get 9 volts at the access point instead of 12 volts?"

The answer is a voltage regulator.  Dick Smith sell a nice little 3 pin
package that will accept up to 30VDC input and output 9VDC.  The Dick
Smith catalogue number is [Z6550] and the regulator has the markings
[7809CT]

Below is a (fairly crummy) ascii drawing of how to wire one...
     

    ----------
    |        | 
    | 7809ct |
    |        |
    |        |
    ----------
    ||  ||  ||
    ||  ||  ||
    ||  ||  ||
    ||  ||  ||
    ||  ||  ||

    1   2   3

If you called the pins 1,2,3 from left to right then the following
applies:
Pin 1. Positive 12v in
Pin 2. Negative 12v in (and negative 9v out)
Pin 3. Positive 9v out

So just run your PoE at 12volts to the end of the CAT5, at the access
point end add a regulator to drop the 12v to 9v.


The cost?  AU$1.35 each inc GST!!!  You might want to add a heatsink to
that though, when you drop voltage it has to go somewhere and that is
out of the regulator in the form of heat.  The regulator has a screw
hole to mount a heatsink off.


Cheers,
               Andy.

andy at geelong.wireless.org.au



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