Introduction: Survival USB Charger: Use Any Power Source to Charge Your Smartphone

Picture of Survival USB Charger: Use Any Power Source to Charge Your Smartphone

You forgot your power adapter for your cell phone? Or there is no electric socket available?

But you need to charge your smart phone urgently?

Let's build a USB Power Adapter, you can use anywhere! So you'll be prepared for an emergency!

Just connect this helpful gadget to any rechargeable battery and charge your phone. Even a AC voltage source like a table lamp will work!


Was machst du, wenn mal keine Steckdose in der Nähe ist oder du kein Netzteil dabei hast?
Wenn dein Handyakku schon unter 5% ist, du aber noch etwas Wichtiges erledigen musst?

Dann bau dir das Allround-USB-Ladegerät!

Damit kannst du überall dein Handy laden! Beim Zelten oder Fahrrad fahren!
Ganz einfach an Batterien oder Akkus von anderen Geräten anschließen und Handyakku laden.
Dieses Ladegerät kann man sogar an Wechselspannungen wie z. B. der Tischlampe anschließen.

Step 1: Parts List

Picture of Parts List

You will need:

- voltage regulator L7805CV
- rectifier, min. 1 A
- capacitor, min. 50 V, 0.1 µF
- capacitor, min. 50 V, 220 µF
- female USB jack, for example from an USB charger
- USB charger or plastic case
- copper plate or heat sink
- cable with alligator clips (or even better 2 alligator clips)
- soldering tin
- wire


Man braucht:

- Spannungsregler L7805CV
- Gleichrichter, min. 1 A
- Kondensator, min. 50 V, 0.1 µF
- Kondensator, min. 50 V, 220 µF
- USB - Female, zum Beispiel aus einem alten USB-Ladegerät
- ein altes USB-Ladegerät oder ein Plastikgehäuse
- eine Kupferplatte oder ein Kühlkörper
- Kabel mit Krokoklemmen
- Kabel
- Lötzinn

Step 2: Prepare the Casing

Picture of Prepare the Casing

First open the casing of the USB Charger and cut off the wires which are connected to the male jack. Desolder the female USB jack. You can use any box you like, but then you have to get the female USB jack from elsewhere.


Als Erstes muss man das Gehäuse des USB-Ladegeräts öffnen und die Kabel zum Stecker trennen. Der USB-Stecker wird ausgebaut. Man kann auch ein anderes Gehäuse verwenden, allerdings muss man dann noch zusätzlich ein passenden USB-Stecker kaufen.

Step 3: Prepare the Wires

Picture of Prepare the Wires

To remove the alligator clips from the short cables, you have to pull the protective cover off. Now you can desolder the alligator clips.

The next step is to cut two 1m long wires and to solder one alligator clip to each one. Don't forget to put the protective cover back on.

If you want to use the plug of the power adaptor as shown in the last picture, just remove the rivets with a pair of pliers. Now you can thread the free cable ends through the holes. To avoid any traction on the solder joints make a knot in each wire as shown in the 4th picture.  

Um die Krokoklemmen von den kurzen Kabeln zu entfernen, müssen die Schutzhüllen erst einmal abgezogen werden, damit man die Klammern ablöten kann. Dann schneidet man sich zwei Kabel mit je 1 m  Länge ab und lötet die Klammern an je ein Ende. Schutzhüllen wieder aufbringen.
Wenn man die Stecker des Ladegeräts benutzen möchte, dann zieht man die Metallbolzen mit einer Zange heraus und fädelt die Kabelenden durch. An der Innenseite müssen zwei Knoten gemacht werden, damit später keine Belastung auf den Lötstellen entsteht.

Step 4: Connecting Rectifier to Voltage Regulator

Picture of Connecting Rectifier to Voltage Regulator

Now we will solder up the elctronic components. The negative pole of the rectifier is connected to the GND (middle pin) of the voltage regulator. The postive pole is soldered to the left pin of the voltage regulator.

Help? Have a look at the pictures in this step.     


Jetzt wird die Eletronik verlötet. Der Minuspol des Gleichrichters kommt an den GND (Mittlerer Pin) des Spannungsreglers.
Der Pluspol an den linken Pin.

Step 5: Connecting Capacitors

Picture of Connecting Capacitors

The capacitors' negative poles have to be connected to the middle pin (GND) of the voltage regulator. The positive pole of the 220 µF capacitor is soldered to the left pin of the L7805CV and the postive pole of the 0.1 µF capacitor is soldered up the right pin of the voltage regulator.


Die beiden Minuspole der Kondensatoren kommen beide an den mittleren Pin (GND) des Spannungsreglers.
Der Pluspol des 220 µF Kondensators wird an den linken Pin und der Pluspol des 0,1 µF Kondensators an den rechten Pin des Spannungsreglers gelötet.

Step 6: Connecting the Copper Plate

Picture of Connecting the Copper Plate

The backside of the L7805CV has to be soldered up the bent copper plate. To achieve the best result we recommend to heat the copper plate with the soldering iron and spread some soldering tin on the surface evenly. Quickly join the back side of the L7805CV to the copper plate. The same procedure is done with the USB female jack. Depending what casing you use you have to solder the USB female plug up the right spot.


Die Rückseite des Spannungsreglers wird an die zurecht gebogene Kupferplatte gelötet. Zuvor muss das Kupfer mit dem Lötkolben erhitzt und mit Lötzinn benetzt werden. Dann wird das Bauteil schnell aufgebracht. Das gleiche wird mit dem USB-Stecker an der passenden Stelle gemacht.

Step 7: Connecting USB to Voltage Regulator

Picture of Connecting USB to Voltage Regulator

As marked in the third picture the positive pole of the USB connector is on the right side, if you look up front. This pin has to be soldered up the right pin of the voltage regulator with a short piece of isolated wire. On the very left of the female USB jack is the ground pin, which has to be connected to the middle pin of the voltage regulator with another piece of isolated wire.  


Am USB-Stecker ist ganz rechts von vorne gesehen der Pluspol. Dieser wird mit dem rechten Pin des Spannungsreglers über ein Stück isoliertes Kabel verbunden. 
Ganz links am USB-Stecker ist der GND, welcher mit dem mittleren Pin des Spannungsreglers ebenfalls über ein Kabel verbunden wird.

Step 8: Finishing Touches

Picture of Finishing Touches

The free ends of the alligator clip cables are soldered up the free pins of the rectifier. The polarity can be ignored in this case. 

Now put everything in the box. It is possible that you have to bent the copper plate or the other components to fit in the casing.

The Survival USB Charger is ready to use!


Die Elektronik ist nun fertig. Die beiden Enden der Kabel mit den Klammern werden an die übrig gebliebenen Pins des Gleichrichters gelötet. Polarität ist egal.
Nun muss alles noch ins Gehäuse gesteckt und eventuell passend gebogen werden.
Das Allround-USB-Ladegerät ist jetzt fertig.

Step 9: Tests

Picture of Tests

The power source you connect to the Survival USB Charger has to have a potential of at least 7 Volt and a maximal potential of 30 Volt. If the potential of the power source is under 7 Volt, also the output voltage will be under 5 Volt.

Possible power sources can be any type of (rechargeable) batteries.

Thanks to the rectifier the power source can even be a alternating voltage source like a table lamp. Have a look at the pictures!

I will use it with a bunch of batteries when I go camping! 

Have you any further possible applications? Leave a comment! 

Thanks :D


Die Spannungsquelle an die man das Allround-USB-Ladegerät nun anschließt, sollte eine Spannung von mindestens 7 Volt und maximal 30 V haben.
Ist es zu wenig, wird auch die Endspannung unter 5V betragen. Dies testet man an den angeschlossenen Polen des USB-Steckers.
Man kann das Ladegerät an verschiedenen Quellen benutzen, z.B. normale Batterien/ Akkus, Bohrmaschinenakku, Kameraakku,...

Dank dem Gleichrichter ist die Polarität egal und man kann das Handy sogar am Wechselstrom der Tischlampe laden!

Ich werde das Allround-USB-Ladegerät vor allem beim Zelten nutzen und einfach ein paar Batterien mitnehmen.

Habt ihr weitere Anwendungsmöglichkeiten? Dann lasst ein Kommentar da! 
Viel Spass beim Basteln


ASCAS (author)2014-01-03

Awesome Idea! I voted BTW :D

Something bothers me a bit, you said "Just connect this helpful gadget to any rechargeable battery and charge your phone. Even a AC voltage source like a table lamp will work!". The 7805 is limited to 30v, why state that you can hook it up to an AC power source? By AC do you mean wall-warts?

Orngrimm (author)2013-12-26

2 things i wanted to point out:
- Charge everywhere... Well... Everywehere where you have 6 or more volts vailable (DC or RMS AC). A single solar cell wont work. So be avare of that to not to be disapointed.
- Some phones (like iPones) need the data-pins pulled to a certain voltage to negotiate that charge-cycle. Google first if your phone is one of those. If so, add a voltage-divider to the 2 data-lines to give them the correct voltage.

Apart from those 2 things, the idea is good and works.
Maybe you could combine it with a modded joule-thief and boost a low DC voltage of lets say a solar cell to 6V+ and feed it thru the charger then... But that would make a bit of loss, since you boost and then linear-regulate down again... Better boost to the correct voltage in the first place...

eelco_g (author)Orngrimm2013-12-29

What you want is something like this, preceded by a bridge rectifier and smoothing capacitor as already shown in this instructable:

Orngrimm (author)eelco_g2013-12-30

I have used exactly those before (and others from DX and also Aliexpress). They work... sort of. I had multiple faulty ones. Mostly bad soldering. Nothing a quick desolder and resoldering with proper geat cannot fix.
But the converter you pointed out is barely able to deliver the 1A continuously without overheating. So if you go in the range of 1A be sure aou add a heatsink to the 2 LM****

eelco_g (author)Orngrimm2014-01-02

Haha indeed Orngrimm. Maybe DX was a bad example :-) What I meant was some sort of automatic step-up/down converter to widen the input range. In a survival situation, you never know what you are going to come be. Some sort of heat sink is always a good idea. Related to that: If this is a true survival power supply, go for military grade components. A lot of 'consumer grade' components die when the temperature drops below freezing. Potting the whole circuit in epoxy is also be an interesting route to explore to make it waterproof.
Personally, I would prefer something that I can shake or crank to generate power in a survival situation, but that is beside the point :-)

Orngrimm (author)eelco_g2014-01-03

Good ideas there!
The range of power-generators start with solar, wind, Muscle (Hand-dynamo), dynamo on your bike, Thermoelectric generator, magnet-shaker, half-dead batteries, batteries not designed for your voltageneeds (12/24V)...

But remember to NOT cover the heatsinks in epoxy... Would render them useless ;)

Noise Maker (author)Orngrimm2013-12-26

Thank you for your detailed comment :D

Yes, of course you can not get energy out of nothing. Using a solar cell is a good idea and I'd like to try it out but I haven't got a big enough solar cell available.

As far as I know an iPhone hasn't even a normal USB Port, has it? I am not sure because I haven't got one but it's good that you told us that :D

That are good ideas but the project would get a lot more difficult for beginners. And if I'm honest I have never worked with low DC voltage regulators before (aren't they more complicated and expensive?)

iamdarkyoshi (author)Noise Maker2013-12-29

Another thing to point out with these regulators: the current draw out is the same as the current draw in. This leads me to believe that the chips mainly just a self regulating resistor...

Orngrimm (author)iamdarkyoshi2013-12-30

Thats correct. A linear regulator (Thats why they are called regulator and not converter) is a small circuit where a transistor greates this much resistance to make a voltagedrop just big enough to come from inputvoltage to the outputvoltage.
So yes: from the outside it is a selfadjusting resistor. :)

Orngrimm (author)Noise Maker2013-12-26

iPhones have a own connector on the phone-side, yes. But those cables often end in a normal USB-plug. You CAN (and normally do) charge iPhones on USB... the added circuit is in the adapter you connect to the iPhone itself.

The thing i was looking for, was the "MightyMintyBoost"... It is a "proper" DC/DC converter using the LT1305.
The magic to make it load a iPhone / iPad is described here: or and many other places.

Depends on what you call complicated... the LT1305 needs 7 additional parts to the chip itself. So yes: It is more complicated. But i could post a 12V to 400V (DC) converter based on OpAmps and FETs and such stuff. But no dedicated IC there... Only off-the-shelf and standard-components... But it has all the bells and whistles attached like automatic frequency-tune, self-regulating duty-cycle, Charge-and-hold-logic... THAT is complicated i assure you! ;)

Price? Sure it is more expensive to go with a real Boost converter instead of a bit more intelligent resistor like L7805CV...
Farnell lists an L7805CV with $0.68 and a LT1305 with $3.65
So yes: about 5 times more expensive... And additional costs for the Resistors, Coils and diode... But thats where you have to decide:
A: Shall it be a simple project, having more then 6V at hand is OK and efficiency is not important --> Go with the 7805. It will work.
B: If you want to dig deeper in electronics and want to have the options of going from 1.5V to 12V as input and coming out with a iPhone-capable highly efficient charger which accepts almost every voltage source (Solar, peltier, semi-dead batteries, lead and alkaline, handcrank ...) you can go with one opf the MANY DC/DC-converters out there. If you take a monolythic one (Switch inside) you dont have to do much math for the switching-part...
But be sure: a bit math is included to set the proper output-voltage.

As i said:
The instructable here WORKS. It has some limitations you have to be avare of so you arent disapointed if you want to charge a iPhone on 2 alkaline-batteries with the 7805: It is a double-No-Go with the 7805-solution posted here.
But if you have 6V and more, add a pair of resistors to it, you are ready to roll with the thing even for iPones! :)

PhilKE3FL (author)Orngrimm2013-12-30

I came across a very nice already built switching circuit from a Chinese supplier for $1.70US to charge a Li-ion battery with up to 1A (free shipping, at least to the USA) This could use down to 4.5 volts and was much more efficient than the LM317 circuit I had designed to do the same thing from a 6V source.

So I looked for a USB supply and found a circuit with input: 0.9 - 5V, output: 5V 500-600mA for $2.80US:

It's not worth designing & building one from scratch! This could work from two to four "dead" AA batteries! Well, at least for awhile :)

DanielNorling (author)2015-04-13

I really like the project. Good stuff.
But why no curcuit schematic? Written in two languages in nine steps. One schematic is probably enough for anyone that actually can get this done. A good description doesn't hurt, and you wrote a good one.


RYM3U4JTJDFKZXHPLZTKAR (author)2015-02-11

I have a 3.6 rechargeable batt and solar pannel that makes 4.5-5v will it work
can I make my own rectifier ? Thanks in advance :)

kunala (author)2014-08-25

Hey thanks @noise maker for putting this up. i made it and it is perfect.

though i was wondering what is the use of .01 micro farad capacitor?

please revert anyone who knows :)

emptyoceans (author)2014-06-06

Awesome! If u selling this or know similar products for sale. I would like to order 20 pieces!

Manu (at)

deejayq (author)2014-01-13

do you think that with something like this could work better?

Timofte Andrei (author)deejayq2014-02-08

i guess it should work. i'm thinking of building a cellphone charger based on this kind of step-down converter, but i need to figure out the values of resistors for D+ and D- pins from the usb plug.

Timofte Andrei (author)2014-02-08

optimus one, the best cellphone ever!

Jkohn19 (author)2014-01-17


jjsims (author)2014-01-07

wow! amazing

cristian 2003 (author)2014-01-06

I made one of those and I'm only 10

Jimmeh30 (author)2014-01-01

I notice there is a little bit of miss information about this circuit's MAX voltage.

According to the data sheet ( ) maximum voltage input for a 5v regulator is 35V DC. This means an ABSOLUTE maximum of 36.4V DC because of the voltage drop of the full wave rectifier.

For AC voltages (without all the maths) after full wave rectification is approximately 1.44 * the RMS AC VOLTAGE ie: a little over 24V AC

Go any further and you'll see the magic smoke.

Also, as has been stated repeatedly but cannot be emphasized enough, PLUGGING THIS INTO 110V or 220/240V AC WILL ONLY RESULT IN A LARGE BANG, FLYING PIECES OF BURNT PAPER, MOLTEN PLASTIC, MOLTEN SILICON, A POSSILBE FATALITY AND IS A REALLY REALLY REALLY BAD IDEA (as is the design of the casing in this ible)

psycotrompus (author)2013-12-26

can it support 220v AC?

Noise Maker (author)psycotrompus2013-12-27

no, max. 30V!

Jimmeh30 (author)Noise Maker2014-01-01

Max 30V DC that is.

dragon26300 (author)2013-12-31

i didn't get why did you add a bridge rectifier when you are already getting a dc voltage from the battery

funglestrumpet (author)2013-12-31

I think the use of what was a mains device is asking for trouble. There is a rule in engineering: 'If it can happen, it will happen'. So, as sure as pigs are pigs, someone will plug this into a mains socket, perhaps without thinking. If the metal tips and wires have been left on, then who knows what will happen. I am fairly sure that the comment in the instructions that it can be used on AC will tempt someone to connect the rectifier input directly to mains supply. Electrical project boxes are cheap enough, surely?

JayGeeBSE (author)2013-12-30

To the person who thought it got a bit warm charging at 1A from a 12V supply - do the maths. 12V supply dropped to 5V means 7V across the regulator. 1A x 7V = 7 watts. About half a small soldering iron. No surprise it gets hot. Anyone considering using up to 30V should consider that the dissipation will get ridiculous.

And as for those mentioning mains, don't even think of it. The unit has exposed non-earthed metal parts and is not remotely safe conected to mains, even if it wasn't going to cook.

iamdarkyoshi (author)JayGeeBSE2013-12-30

yes, 7 watts is quite a bit of dissipated heat. the reason i didnt plug the roku into the van's inverter is because every time the vehicle starts, the roku has to reboot. i just had a small 12v battery plugged into the cig lighter and the regulator on it. this way the battery would hold up the regulator as the vehicle starts.

ferjanyen (author)2013-12-29

Nice instructable but a circuit diagram would be very helpfull.

Orngrimm (author)ferjanyen2013-12-30

The values of the caps may not be the same as posted by the OP.

ak08820 (author)2013-12-30

What is the difference between this and a charging adapter for an automobile? Would it be possible to equip that with the alligator clips?

Orngrimm (author)ak088202013-12-30

Charging-adapters in cars normally are converters. This one is a regulator.
A regulator drops voltage and converts the overflow into heat. A converter converts the voltage to what you need and wastes only a fraction of the energy.

PhilKE3FL (author)2013-12-30

I don't have a iPhone but I had an iPod that required the same voltage on the data-pins. This is in the USB standard, it is the method used to indicate that the charger can supply high current, ~1A. The simplest way I found to "fool" the iPod into accepting the charger as a high-power charger source was to simply tie the two data-pins together. I guess the iPod supplied the needed voltage to itself.

capetry (author)2013-12-30

How about putting a light bulb in series with the charger to be able to plug it on 220V!

mihaiachim (author)2013-12-29

Not very clear for me if this system work with ~220V or just up to ~30V and continuous voltage?
I think is not working with ~220V can you confirm this?

Treknology (author)mihaiachim2013-12-30

This is not going to work on mains voltage. Stick to 30V as the limit.

If you have access to 110/220VAC, it is also likely you have access to a standard USB charger. (author)mihaiachim2013-12-29

I am fairly certain it is only up to 30v. You may get away with a little more because it is rectified ac but I wouldn't give it anything over 50. Assuming the ac frequency is 60 hz you get 60 pulses of actual 220v every second. the majority of the time it is actually below that point. I would add a switch with another circuit which either has a 25v voltage limiter, or an ac transformer which then feeds into the circuit in this instructable.

buteman (author)jj.inc2013-12-30

Sorry, but because of the 220 microfarad capacitor, the input voltage to the voltage regulator will rise to near to the RMS voltage of the A.C supply so on 220 volts it will be around 220 volts.The regulator will fail and this might be in such a way that your phone could be damaged.

The Lightning Stalker (author)2013-12-29

It might not be encountered often, but it should be noted that the maximum input voltage for the L7805CV is 35V.

0805 surface mount capacitors will fit perfectly on the pins of the L7805.

iamdarkyoshi (author)2013-12-29

Nice instructable! I have used the lm7805 before to power my roku in the van. The chip got so hot running the roku, which pulls 1A average. I needed a cpu heatsink to keep it cooled down, even though its only running 12v to 5v. To anyone using it, watch your temperatures. Charging a tablet may heat it up quite alot.

ferjanyen (author)2013-12-29

This is also a good idea but leave leads with different lengths to advoid short circuit.

TSellers22 (author)2013-12-29

For those that may be looking for a simpler and economical solution to this charging problem, they could also consider something like the Li-ion Battery USB Emergency Charger Power Bank like the ENB that uses user replaceable 18650 Li-Ion cells and costs less than $10.00. User could expect to get at least 5 charges on most Smartphones when using 3400mAH cells in the PowerBank, and it also charges any other USB device.

chrwei (author)2013-12-27

for a simple addition, adding a 200 ohm resistor between the 2 data pins on the USB socket will allow Android devices to charge much faster.

xKOBAYASHIMARUx (author)chrwei2013-12-29

Actually that's mostly likely just for your phone, but good catch! Most phones nowaday (especially smartphones) require a certain voltage level between the data pins which IS easily done with a simple 2 resistor voltage divider. But ask the all-knowing Mr. Google to be sure 200 ohms will work for your phone! :)

tiger12506 (author)2013-12-29

An excellent idea!

I would be careful saying "table lamps". The only table lamps that came to my mind run on mains, and people might not catch the "max potential of 30 volt" on the last page.

Having said all that, I think you would be better served by modifying the existing contents of the charger, rather than building your own. It might take a bit of probing, but it shouldn't be difficult to find the low side of the internal transformer, so that you can put alligator clips on it, the idea being to allow for both charging normally through wall, or through the alligator clips. Could even put protection diodes on alligator clips so that wall charging will not leak power out through clips.

Vehicle-based sources are another example of where this might be used.

Todd Gehris (author)2013-12-29

The bridge rectifier is a really good idea. It is nice to not worry about the polarity when you hook it up.

Todd Gehris (author)2013-12-29

I had tried something very similar. I discovered the 7805 didn't allow enough amperage to charge some devices. I had to place another chip after it. Can't remember what I had used though.

bbrown56 (author)2013-12-29

Great idea. Thank you for sharing and in such detail. I'm gonna make one and add it to our emergency kit. It won't use much room!

tutdude98 (author)2013-12-25 what kind of battery is that?

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