Introduction: Easy USB Charger

Picture of Easy USB Charger

This is an easy USB charger because you can get the electronic booster board already assembled. Just add the batteries, a couple of capacitors, the usb connector and nothing else.

Step 1: Materials

Picture of Materials

The main component is the PTN04050, it takes the 2.4 volts from the batteries and raise it to 5 volts for the USB. You can get it from the Texas Instruments site here.
You will also need:
2 100uf capacitor
1 USB female connector
1 battery holder

Step 2: Assembly

Picture of Assembly

The assembly is pretty easy, just follow the scheme. Try to not overheat the terminal of the PTN04050 and be careful with the polarity of the USB connector.

Step 3: Finish

Picture of Finish

Find a nice case for your charger, an Altoids tin would be great, but I can't find one of that in my country so I will keep look for a case.
For testing the device at first I used my USB tester and then I tried it with my mp3 player, but there shouldn't be any problem if I were careful with the assembly.


happyhippy1 (author)2016-01-31

does anybody know if this will damage an iphone 4s at all

RTAdams89 (author)2011-10-16

The data sheet for the PTN04050a says the minimum input voltage should be 2.9v. New alkaline batteries would output 3.0v, but as they are run down (or if you started with rechargeable batters putting out only 2.4v) you would have less than the 2.9v required. I'm assuming you tested this for a while and it worked, but this may put stress on the chip that will cause it to fail prematurely.

Also (and perhaps more importantly), the data for that chip says that a resister is required between pins 1 and 4 to set the output voltage. If no resister is used, thoutputtdefaultsls to -1.79volts, which is not only wrong for USB, but is also outside the chipoperatinggn range. I don't see a resistementionednd in your write up at all, so how on earth did you get this to work?

Ploopy (author)RTAdams892014-04-26

I took this picture from a datasheet just look in case of questions

Cool Instructable by the way!

brunoip (author)RTAdams892011-10-16

You are right with the voltage, but I made it and I have been using it with regular and rechargeables batteries for a few moths with no problem.
The datasheet says "open" in the resistor for 5 volts, so you don't have to use any.
Ragards, Bruno.

scottinnh (author)brunoip2011-10-16

If you can, when your batteries are dead please measure their remaining voltage. I thing you will find there is usable power In the dead batteries.

So 3x AAA would be far more efficient.

Good find on this chip. I scoured the TI site for something like this, but I guess I looked too hard under DC-DC and not this section. This chip looks really strong... Max 12W means you could adapt for an iPad charger.. Sweet!

asfi235 (author)scottinnh2011-10-19

The trouble with using 3 batteries is that fully charged ones will run afoul of the maximum input voltage specification, which is the lesser of 5.5V (okay, that's not the issue) or the output voltage minus half a volt (i.e. 4.5 V).

It's probably safer to undervoltage the input than to overvoltage it....and it's also one less battery. :-/

scottinnh (author)asfi2352011-10-19

I think you misunderstand something. The author was using 2 AA batteries and a boost circuit that maintains exact 5v output (from ~2x.5v input).

Note that this Texas Instruments chip is designed to work with undervoltage... "anything" under 5V is boosted to 5v... but the more you undervolt, the less efficient the TI boost circuit will operate.

I proposed making the input 3xAA or 3x1.5v (nominal 4.5v input). The advantage is twofold: greater capacity, and greater efficiency in voltage conversion by the boost.

It's true that new batteries will contain > 1.5v (1.65v being common), but 3x1.65 = 4.95v. Even if the batteries were 1.7v, that is still 5.1v total which is far less than USB max of 5.5v.

asfi235 (author)scottinnh2011-10-23

Did you read the TI datasheet? Please have a gander at the "input voltage specifications" part.

ac-dc (author)RTAdams892011-10-16

lol, no it will not "put stress on the chip that will cause it to fail prematurely".

What it does instead, is makes this instructable poorly thought out because you can't use more than a small fraction of the battery capacity. Instead of 2 x alkaline cells it should use 3, or a different boost circuit.

GASSYPOOTS (author)2012-03-19

it no work with psp

techboy411 (author)2012-01-02

an IPad will be more "picky"

Tchnclfl (author)2011-11-21

Just as an FYI - You can order samples of this item if you have a company (or if you enter a company name in TI's registration fields). The samples are free. I DO NOT recommend abusing this. I simply think those who own electronics companies should know.

Kante Tech (author)2011-11-06

I tried this and it did not work it couldnt even charge my motorola phone. the w765 or somehing.

nurdee1 (author)2011-10-25

No Altoids tins in your country that is TERRIBLE!!!!!!!! that's like not having duck tape.

aeneas shrike (author)2011-10-22

I'm not very good with schematics. Is my terribly drawn in mspaint translation correct? and could someone fill me in on the ? I've placed in there? thanks!

sorry, bad labeling...

jphphotography (author)2011-10-19

Pin 1 VCC (+5 V)
Pin 2 Data-
Pin 3 Data+
Pin 4 Ground

josephthorpwausau (author)2011-10-17

im a storm chaser and need to charge usb instermentsin my truck you should do one like this one but step it down from 12v car to 5v i would love to see that one

Just FYI if you're really in need of something like that there are tons of devices out there like this

However if you want to build your own you can check out this instructable

asfi235 (author)2011-10-19

Why is the output capacitor placed on the USB connector instead of at the module? Quoting from TI's datasheet: "The stability of the module and voltage tolerances are compromised if the capacitor is not placed near the output pin."

Granted, it's good practice to place an electrolytic close to the load, that's primarily to improve transient response (also as noted in the datasheet) though for charging applications, load transients may be minimal (but YMMV, as always).

Woodenbikes (author)2011-10-16

How would you make one with 4 or 5 batteries to get up around the 5 volts needed? Would the electronics be any simpler or cheaper?

KevinAlien26 (author)Woodenbikes2011-10-18

Get yourself a cheap car charger for your phone, the inside board will already be capable of dropping ur Vs to the desired mount. This should work as long as ur batteries aren't too low or too high in volts. (and beware, think and ask yourself if potentially damaging 400$ worth of electronics is worth getting a few more hours of charge)

Lrr (author)Woodenbikes2011-10-16

You can't get exactly 5 volts from 1.5v batteries, so Im pretty sure you'd need the regulator no matter what.

acoleman3 (author)2011-10-16

how well would this charge a 6th gen ipod nano? its an 8 gig model if that makes any difference.

tycoonist (author)acoleman32011-10-17

You will need 1 150k resistor and 1 100k resistor. Tie on end of the 150k to the +5, and on end to the 100k. Then take the open end of the 100k and connect it to ground. Then attach a lead to the connection between the 2 resistors and connect it to the 2 data pins on the usb. That should let it work. The device should draw about 600mA total from the batteries.

I recently built an iPhone solar charger. I had the same problem.

could you show this in a real life pic and not a dig. i would like to see how that looks

I would really love to show you a pic, but I am currently upgrading the system to make it charge better. I will upload a picture of the upgrade when i'm done, but right now it's all torn apart.

acoleman3 (author)tycoonist2011-10-18

oh bang on! thanks

walkerman1980 (author)2011-10-18

UPDATE: the module that this poster mentioned is available via the ti website as a free sample. you can click the link the poster provides which will directly place you at the right module. click sample or buy and register a myti account. note you MUST provide a business name(i use my last name combined with the hobby im into which is legal by law and you do not need a verified business with the government either) you must also provide a url so just sign up for a free website at or similar and activate the account. you do not need to create a webpage. than continue with the sample checkout. it will ask for end user info. click same as button unless youd like it sent elsewhere, check out and youll get the fedex confirmation email next day or same day if its between 9-5.

im getting mine tomorrow:) and along with that when alls said and done ti gives you other tsamples you may be interested in in the same emails. click them to get more free samples. you must choose standard ship in order to be totally free of cost.
ti only allows 5 samples per request but multiple requests may be possible. choose any type of business you want i put electronics amusement as mine.

hope this info helps those trying to build these.

sweet instructable i will post my results when my module arrives:)

Razanur (author)2011-10-18

Just use the wikipedia-article about usb.

ginbot86 (author)2011-10-17

I've sampled this boost circuit a lot of times, and the boost converter will work down to about 2.2 volts before dropping out completely. For two 1.2 volt batteries, this is fine since the voltage curve of Ni-MH cells flattens out near 2.4 volts for much of its lifetime.

mrmerino (author)2011-10-13

i wonder if you could substitute a solar panel for the battery?

jkanary (author)mrmerino2011-10-16

Search "solar mintyboost" in google, and you'll see the adafruit site. Adding a solar panel will likely increase the cost almost 5 times over (or at least it would if you do it their way). The mintyboost is similar to this 'ible (at $20 per kit), but the solar one can run up to $90, depending on which battery you use. Regardless, the site has some good explanation of how the electronics works. I was searching for something that would charge an iPad 2.

speedstix (author)mrmerino2011-10-16

You could. I did it for my final year project. We had panel -> peak power detector -> boost converter to adjust panel voltage for max power -> batteries.

blinkyblinky (author)mrmerino2011-10-14

Depends on the current requirement.

brunoip (author)2011-10-16

Mine is a PTN04050 CAH

kostya (author)2011-10-14

Looks nice. I think you should reverse the output capacitor position at the schematic.

brunoip (author)kostya2011-10-14

Right, I have to fix that, thanks.

snowluck2345 (author)2011-10-13

what type of mp3 player is that?

brunoip (author)snowluck23452011-10-13

Sony nwd-b103f

About This Instructable




Bio: Robots and video games...
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