Magnetic Fridge RGB LED Frame




Introduction: Magnetic Fridge RGB LED Frame

With this project your photos, fridge magnets or whatever you want can shining on your fridge in the darkness.

It is a very easy DIY and not expensive project it likes very much to my sons so I want to share with you.

I hope you like it.


  • Two terminals 5 mm RGB color changing LEDs
  • Metal rods (2 mm diameter)
  • Piece of wood cilinder (30 mm diameter) (30 mm height)
  • 3V 150 mAh lipo battery with JST 2mm male connector (with built in over-discharge protection voltage)
  • Little switch
  • Adhesive circular magnets (30 mm diameter)
  • Insulated tape
  • Female JST 2 mm connectors
  • USB to JST 2mm lipo battery charge cable
  • Wires

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Step 1: Choose the Shape and Build It

The first step is to choose the shape of the frame.

So you have to cut pieces of metal rods and solder them to form the shape you like.

As you can see in the image you have to build two frames with the same shape but one of them is smaller because we are to going to solder the RGB leds between them

Step 2: Solder the RGB Leds

As you can see in the first image I am using two terminals RGB leds: anode (+) and cathode (-). You have to solder the leds always in the same position.

I have chosen the external frame be the anode and the internal one the cathode as you can see in the second image.

At the end the leds will hold the frames together.

Step 3: Test the Frame

To test the frame you have to connect the frame acting as anode to the positive of a 3V battery and the cathode one to the negative of the battery

Step 4: Connect the Electric Circuit

Because I am using a metal little switch, I have pasted a little piece of isolated tape in one of the frames to avoid the cortocircuit as you can see in the photo.

I have chosen to solder the positive terminal of a female connector to the frame acting as anode directly and the negative one to the switch, and finally to the frame acting as cathode

The lipo battery has a male conector so I have to use a female connector in the frame as you can see in the second photo.

Step 5: Build the Magnetic Foot Frame

In the first photo you can see the battery we have to install inside the wood cylinder. To do that, I have opened two holes. One of them to allow insert the battery and the other hole on one side of the wood cylinder to pass through it the conector to charge the battery. In the second picture you can see the final rersult.

After that we have to open a little hole (2 mm diameter) in the opposite side to insert a square metal rod bent at a right angle. On this metal rod we will solder the frames.

In the last photo you can see the round magnet pasted on the base of the cylinder wood covering the battery hole.

With a 3D printer everything would be more easy and cool.

Step 6: Mount the Magnetic Led Frame and Charge the Lipo Battery

Once you have soldered all the leds and tested the frames (first picture), you have to solder a little piece of metal rod in one of the frames as you can see in the second photo and paste a little piece of isolated tape in the other one to avoid the cortocircuit.

After that you just only to insert the metal rod in the little hole on the foot frame and you have finished the project.

Using a USB JST 2mm cable you can charge the lipo battery as you can see in the last photo.

Step 7: How It Looks

Step 8: Summarizing

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    10 Discussions


    6 days ago

    Only problem is you're going to kill the battery and/or the LEDs as it stands. Use a pair of NiCad batteries that can handle the lower voltage drains and add a resistor (either one on the battery wires or, best, one on each LED, of the correct amount. Use a LED calculator to figure out what resistance is needed.)


    Reply 4 days ago

    Thank you for your comment but you have to take into account that the leds are connected in paralell and they will receive the same voltage (about 3,5 V) and this voltage is the typical forward voltage for a 5mm led. With the battery I have used in the project (150 mAh) a frame with less than 10 leds can shine continously about 1 hour. If you want your frame to shine more time, just use a more powerful lipo battery.


    Reply 3 days ago

    You don't have it specified what colors you're using but LEDS have different voltage-drops for different colors. This can vary from as little as 1.7v for red ones to a peak of 3.5 for blues and purples. If they are 1.7v reds, they will drain the batteries down to 1.7v, which will destroy it (any color with a forward drop of less than 3v will kill the battery, and I don't mean "as in drain it." I mean as in "it'll be no good afterwards and might as well be trashed.") So you'd want some sort of a battery-monitoring circuit that will shut it down if the battery is getting too low. Or just use two or three NiCads that can handle being drained to 0.8v or so. If using red, orange, yellow or green LEDs, use two NiCads. If using blue or purple or any of the COB white LEDs (they look like a bit of yellow beeswax in a small frame and output a warm or cool white) then use three NiCads.

    LiPo batteries can put out anywhere from 5-20C (i.e. an amperage of 5-20 times the capacity in Ah.) So a 150mAh can, in theory, put out 900mA or more. For 6 LEDs, you're now forcing 150mA through EACH ONE. LEDs should normally have no more than 20mA put through them (of course exceptions exist, such as a laser diode with a heat-sink, etc.) So you're running the risk of overloading them. Even if the battery is only capable of putting out 1C (150mA), for the triangle, you're still over spec with 25mA/led. And "If you want your frame to shine more time, [and you] use a more powerful lipo battery." you're going to get a battery that probably has a higher discharge rate and that would push even more amperage through the LEDs and kill them even faster.

    Throw a 1000mAh 10C battery on there with no limiting resistors and you're going to get 10 AMPS through your LEDS. They may put Broadway to shame. But only for a few seconds. Then one will give up the magic smoke, forcing even more current through the others. Then another will die. As each dies, the others get more power and the resulting meltdown will mimic Chernobyl.

    So I stand by my original statements that:

    1) LiPo batteries are not good for this project (without a monitoring/protection circuit.)
    2) The LEDs can drain a LiPo below the recommended minimum (unless they're blue or violet.)
    3) The circuit NEEDS power-reducing resistors to keep from pushing too much current through the LEDs and burning them out.

    The project is a great idea and I'm not putting.that down. I'm simply trying to explain what should be modified to make it more successful. Other people will try to use red LEDs with a drop of 1.7-2v and then wonder why their battery is swollen up to look like Octo-Mom with eight babies. Or they try using a higher capacity battery and wonder what they did wrong as they watch the fireworks of the LEDs dying.


    Reply 2 days ago

    Again, thank you for your explanation.
    The battery I have used has a built in over-discharge protection voltage (around 2,5V) . I have been measuring with the voltmeter and waiting for the battery reaches this threshold voltage. When it happens the battery cut off the voltage and the frame turn off.
    Until now I have not had any problem with the leds or the batteries of the frames. The batteries has been charged several times without incidents


    Reply 2 days ago

    Yes, IF the battery has an added over-discharge protection circuit, then it's fine as far as not draining it too much. But in your bill-of-materials. you simply say "3V 150 mAh lipo battery with JST 2mm male connector." and there are batteries around that have the connector (or that such a connector can be easily added to) that do not have the protection circuit already added. Those batteries will be killed if used. So a simple "make sure the battery has over-discharge protection" would have been great there.

    Now your battery may also have in that same circuit a current limiter. IF it has such and IF that limit is below a set point, your LEDs will be fine. But "use a more powerful lipo battery" means usually using one that can output more current (even if it has a current-limiter, a 1000mAh battery may be limited to 1000mA current, where-as your 150mAh battery may be limited to 75mA. Hooking up the 1000mAh battery will make your LEDs burn brighter, all right. Right up to the point that they self-destruct.)

    Again, not using current-limiting resistors is asking for trouble and simply hoping and praying that the battery will handle it is poor design (some batteries, such as button batteries, simply can't put out enough current to kill an LED. Some SMALL LiPo batteries may have a current-limiter that's low enough to not kill several LEDs used together. But I wouldn't want to rely on "might" and "maybe" and "if." Sure, if you use enough LEDs in parallel, you could hook them up to a car battery with no current-limiter. But make one small miscalculation and you fry the whole lot. Using an appropriate current-limiting system prevents any such issues and avoids any "well, it worked for ME.")


    Reply 1 day ago

    You are right. I forgot to include the over-discharge protection in the specifications of the lipo battery. I have just included. Thank you.


    8 days ago

    Pretty cool design. Can't wait to try it.


    Reply 8 days ago

    Many thanks for your comment


    17 days ago

    Great idea! :D


    Reply 17 days ago

    Thank you for your comment jessyratfink