Magnetic Refrigerator Lights

Step 4 Hook Up The Power

I used a 4.5 Volt / 500 milliAmp AC power adapter with magnets attached to both wires to power the grid. The wires are glued to the magnets and the tops (not bottoms) of the magnets are covered in hot glue to prevent the two magnets from shorting the circuit should they touch each other. The magnets can be oriented so that the bottoms are magnetically opposed - which should prevent them from attaching to each other if they get pulled from the fridge.

There is a gap in the circuit between the door and the side panel of the fridge. To complete the circuit, I used two small jumper wires with magnets attached to both ends. Make sure to leave enough slack in the wires to cover the gap even when the fridge door is opened all the way.

Now the grid has power. Since the LEDs are not constructed yet, you may test the circuit simply by placing some magnets onto the traces of the grid and lying some LEDs over the magnets. The pins/wires on LEDs are attracted to the magnets, so no special effort is required for this test.

I measure 15 Ohms of resistance on each trace going from the back of the fridge to the grid, and about another 15 Ohms from the side of the grid to the center. When I place a jumper wire in the center of the grid, I measure about 60 Ohms between both power terminals at the back of the fridge - so a full circuit between the power supply, crossing any given point of the grid and back to the power supply is about 60 Ohms.

I found that the conductivity of the paint increased as the paint dried, so don't be too worried if you're getting readings higher than that at first. If you get something much higher or much lower, you may opt to use a different voltage power supply to compensate or use copper tape to reduce resistance in the traces.

Comments

[simply_vibrant]

Can you put a picture up of the wires attached to the AC adapter?

[andrestuff]

Our Dollar Stores here in California don't have those ... I know I go and look at most of the stuff. Which store in particular has them?

[GitarGr8]

I bought a bunch from KJ Magnetics for the keyboard refrigerator instructable. I went with the cheaper surplus magnets and they worked out great.

[SacTownSue]

I live in CA. Sacramento. I bought them, last week, at Dollar Tree. Look high and low. I thought they might be discontinued because of lawsuits. But they had a few left after I got mine. Then you also have steel balls galore for the Roly Poly LED too. If only Costco carried the LEDs in a 55 gal drum...
I love LEDs.

[Andyjo]

you can get a large set of the 'linkz' at toys r' us
"mega magz"
http://www.toysrus.com/product/index.jsp?productId=2309608&cp=&sr=1&f=Taxonomy%2FTRUS%2F2254197&origkw=magnetic&kw=magnetic&parentPage=search
14 bucks for 94 sets of magnets.

[SacTownSue]

$tores now carries a similar toy. 23 mags in one pkg. Count varies.

[Spinergy]

There's an easy and attractive way of bridging the door-to-fridge gap. Simply pleat {accordion fold} strips of copper foil tape then secure the ends with magnets.

[montesol]

those linkz toys are in danger of being discontinued because small kids have been swallowing the magnets, which pinch parts of their digestive tract, cause infection and eventually death. so get them cheaply while you can, or else it will be back to the specialty aisle for them.