Emergency USB Charger




About: I have been building since I was 4 and growing plants since I was 5.

You may be camping in the woods, experiencing a natural disaster, or in a place where electricity is unavailable. You may want to charge your phone to keep updated on news or stay connected with friends or family. This device works with apple, android, and many other phones/ MP3 players 

Step 1: Drill and Cut

Now you take your encasement and you mark out where each of your plugs go. You can decide yourself or model it off of what I did. When all are cut/drilled, glue all securely in place.

Step 2: Soldering

Solder on the wires to the correct plugs. I suggest color coding. NOTE: only solder wires onto the USB an banana plugs. Now, the two middle prongs are for data. In order to charge a apple device, you must add on two 150k OHM resistors to the circuit. Follow the diagram I created below for hook up details. Also keep in mind that this comes AFTER the regulator is hooked up so only solder the two resistors onto the data prongs for now.

Step 3: Regulator and Plug Placement

Glue the floppy disk plug to the encasement and let dry. Use 3 of the wires (yellow+two blacks) for the regulator and push the red out of the way. The picture below gives the pinout of the regulator. So basically input is the battery or solar panel, ground is negative, and output is 5v for the USB. NOTE: do not attach any other wires yet.

Step 4: Connecting the Wires

Follow the diagram to hook up the wires. In case you don't understand it, here is instructions on how to do it. take the positive in and connect it to the the yellow wire on the floppy disk plug. Then, connect both negative wires from the USB and banana jacks by twisting them together. Then connect them to the first black wire on the floppy disk plug. Then connect the positive USB wire to the second black wire.

Step 5: Insulating and Finishing

Once all the wires are connected  properly, wrap electrical tape around all of the exposed wires that we twisted together. Then put a heat sink on the back of the regulator. Next bend all three pins at a 90 degree angle so that the pins are in front of the writing. then insert into the plug. make sure that they are in the yellow and the 2 black slots. no pins should be in the red slot.

Step 6: Tips and Pointers

You can use a whole range of power sources to use this. So far, i have used solar panels and a 9v battery. If you use a 9v battery, it continuously charges until its voltage drops below a certain level. With solar panels, It charges for as long a you have enough light. One problem is that you have to come up with at least 10v to charge one device. I have not tried charging two devices yet but it is possible. If you have any questions, please ask me and I will get back to you as soon as possible. 



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    6 Discussions

    Samuel kos

    5 years ago

    Also make sure you have the two middle leads on the USB shorted out that can keep apple products from charging

    wout smeets

    5 years ago

    i think but I'm not sure. that some Android devices need this kind to I had a site with al the value s but I can't find it anywhere I Wil post the site if I can find it back and no problem for letting you now

    2 replies

    Thanks again and I originally tested this on two of my android devices. It worked on my LG optimus and on my asus tablet, It charged both. I will add a apple feature soon and find out about the android. Thanks for all of your help!


    her you go this should work on android devices
    for apple you need voltage dividers like in the schematics posted before

    wout smeets

    5 years ago

    this would not work with Apple devices, beacause the lack of controlling d- and d+ please take a look at this http://learn.adafruit.com/assets/5784 or this http://learn.adafruit.com/assets/5796 or this http://learn.adafruit.com/assets/5809

    1 reply

    So I see... Thank you for this alert i tested this on my friend's iphone and like you said, it doesn't work. Thank you for the circuit, looks like i have some revising to do. I am guessing that apple products have a safety on them so that they can only be charged with a computer or charger. I will look into this and try your circuit. Thank you for the feedback