Audible AC Power-off Alarm

I have a freezer that is located in the garage. During a recent renovation in the garage, the electrician was required to put all the circuits in the garage (including the
freezer) on a GFCI (Ground Fault Circuit Interrupter). He warned me that if the GFCI trips, there might be no indication inside the rest of the house that there is trouble,
and I could potentially lose the contents of the freezer before I notice the problem. He also said that to the best of his knowledge, there is no audible alarm available on
the market.

I checked around and could not find one, though I did find several rechargeable flashlights that can be set to automatically come on in the case of a power failure. One
such product is available at Radio Shack under the name "Eton American Red Cross Blackout Buddy" (part # 20-019) for $14.99.

The Blackout Buddy has three LEDs at one end and one LED at the other. There is a red switch on the top of the case that turns on the three LED end and an
"OFF/Auto" switch on the side that turns on the one LED end. The three LEDs will only light when the Blackout Buddy is disconnected from AC power and the top cover
switch is turned On. The one LED end is a nightlight and will only light when the side switch is in the "Auto" position and the room is sufficiently dark.

Radio Shack also sells several buzzers that could be attached in place of one of the LEDs. Once complete, when the LEDs light up, the buzzer also goes off.

Some of this project sounds like an advert for Radio Shack. Other than living in the Ft. Worth, Tx area, I have no connection with Radio Shack. I will not be
compensated in any way if you purchase any or all of these components at Radio Shack.

Of course it must be noted that making these changes to the Blackout Buddy will definitely void its warranty.

For this project, I purchased the following at Radio Shack:

Eton Blackout Buddy   (RS Part # 20-019)  $14.99
Pulsing Piezo Buzzer  (RS Part # 273-0066) $5.49

You will need the following tools:
T6 Torx driver
Small Phillips screwdriver
Small flat screwdriver for separating case
{all three of these are available as part of a set at Radio Shack (RS Part # 64-071)}
Diagonal cutters
Soldering iron
Solder
Hot melt glue gun
Hot melt glue

First, use the #6 Torx driver to remove four screws from the back of the Blackout Buddy.   Flip the unit over on its back and use the regular flat screwdriver to separate the two case halves.  The lenses for the LEDs on each end snap into the top cover, so slip the screwdriver under the corners of the cover where it meets the lenses to release. 

Once the cover comes unsnapped from the lenses, it should lift off the unit easily.  This will leave the circuit board exposed.

There are six screws holding the circuit board to the bottom case half.  Remove these six screws and lift the circuit board out of the case.

Pulling gently on the lens covers will separate them from the circuit board. 

At this point, you need to decide how much of the rest of the unit you will disassemble.  The end of the Blackout Buddy with three LEDs lights up when the Blackout Buddy is not connected to AC power and the top switch is set correctly.  The buzzer will work fine if you clip off any one of the LEDs and solder the buzzer in its place on the circuit board.  However, when the power goes off, the other two LEDs will be lit and that will certainly shorten the life of the battery.

Even though I could have left one or two of the three LEDs on the circuit board to act as a flash light during a power outage, I chose to remove all three of the LEDs to extend battery life as long as possible.  In my application, I don't need to SEE whether there is a power outage ... I need to HEAR that there is a power outage. 

Use the diagonal cutters to clip the three LEDs off circuit board, leaving as much of the leads from one of the LEDs as possible. Luckily, the bottom side of the circuit board where the LEDs are attached has one lead marked positive (+). I soldered the red wire from the buzzer to the lead marked + and the black wire to the other. 

If you wish, you could drill a hole through the lens, feed the wire through the hole and then complete the connection.  Since I was taking all the LEDs off the board, I chose to leave the lens off the Blackout Buddy entirely.  This could turn out to be a mistake because it does leave one end of the package open to the elements and critters may decide to nest inside.  Time will tell.

Finally, reassemble the Blackout Buddy in the reverse order of dis-assembly and attach the buzzer to the top case.  Please note that if you want to leave the night light function in working order, you must leave the hole in the top case that allows the light sensor to be exposed open.  You can see the hole in the case in the picture on the left side between the buzzer and the leads to the buzzer.

Use hot melt glue to attach the buzzer to the case and to keep the leads from moving around.

To test the unit, just press the button to the right of the buzzer.  The buzzer should sound, but turn off as soon as you plug the unit into the wall. 

Test it by unplugging it from the wall.  If the button is in the correct position, it should start sounding as soon as the unit is unplugged.

Thanks for reading through this.  Any suggestions, improvements, and comments are welcome.