9v USB Charger


Introduction: 9v USB Charger

About: Not much to say-I am who I am

very easy USB 9 volt charger

Step 1: Parts List

L78M05CV  5V 500 Ma voltage regulator
9 volt battery snap
USB connector (female) ,or phone charger plug
of course soldering iron and some solder.
optional - extra wire ,heat shrink ,recharge able 9v battery ,multimeter (for checking if all are working correctly.)
I bought 9v 250 Mah battery for 6$. I think if you build this you'll need recharge able battery. For wire i just use wire from 9v battery snap.

Step 2: SOOO Easy!

this step will show you how to connect parts correctly.
on usb that 2 middle pins you can just snap off.
voltage regulator's numbers side up.

Step 3: Finally You Can Now Charge Portably.

that device can charge anything what charges with 5 volts,only what you need to do is change usb to nokia , or any other  5 volt charing device plug. thank you for viewing this instructable !!! :)



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Linear regulator is horrible for applications like this. You are way better off using 2 AA batteries and a boost converter. Or if you must use a 9v, use a switch mode regulator. They're huge but less wasteful.

Most smart phone batteries are 1500-3300mah.

A 9V battery has 50-400mah and at 500mw load has less than 300mah capacity.

You're also losing 30% of that 300mah thru the 7805 as heat.

Just exactly HOW much does this remaining 210mah charge your phone ???

Ref : http://www.powerstream.com/9V-Alkaline-tests.htm

this charger works for 5 secs after that it do not charge my phone but after disconnecting it and connecting it again with my phone it works for 5 secs again

1 reply

That's because 9V batteries die under the +500mah load.

This is a stupid project.

the worst circuit ever . first i really think u should use a buck converter circuit (much higher efficiency) ,you can make it your self or buy a premade one . change the potentiometer (resistor) with a screwdriver in the circuit so it output 5v ) https://www.youtube.com/watch?v=CEhBN5_fO5o

as of why the circuit is bad is because the linear regulator has to dissipate 2 w without any sort of heatsink (9-5=4 volt , 4*0.5A , 2W ) the regulator can not dissipate 2 w , it have thermal limit that stop output when reach 150 degrée (so it doesn't blow ) it will literally output a hashed voltage and u phone will not like it

Voltage regulaters are the worse for circuits that involve batteries. You are literally wasting the most of the energy on heat

I'm sorry, but that really is the worst possible design for a phone charger imaginable.

1. Where are the capacitors for the voltage regulator?

2. Why are there no D+ and D- resistors to enable charge mode?

3. How do you expect to charge a (typically 1500mAh) phone battery from a 500mAh 9V battery? (150mAh if you use a rechargeable one...!).

With modification it might allow you to use a brand new Alkaline battery to charge the phone enough to make an emergency call, as long as you don't want to say much.

Would you be able to use this with a 9v power adapter? I need USB power from my pedal board. I have extra 9v cables, and I need to power a usb device on the board without running any extra power supplies. Could I use this adapter from the 9v power supply?

can I use such things like this (5v regulator) for the newer apple lightning connectors?mor do I need a different regulator?

using this circuit output raises from 5v to 6.6v after 30 min (input voltage 7.5v from adapter)

if we supply 12v instead of 9v then will it work????
can we charge more than 2-3 mobile phones at a one time???????
plz rply

2 replies

12v will work fine. If you add more usb conectors (red with red and black with black wire) on output conections , then you could charge multiple devices at the same time.

Be careful supplying much more than the intended voltage coming out of the voltage regulator. Cheaper 5v regulators have a drop-off voltage of about 2v, meaning you need to power it with at least 7v for it to deliver a proper 5v, but using more input voltage will result in significantly more heat coming from your regulator in which you really need a heatsink or you will most certainly melt the back of that plastic casing for your batteries!!! I have burnt myself more than once this way :)

sorry but your circuit is wrong.... the way you have it drawn the gnd on the regulator is going to the posotive side of the battery and that doesnt make any sense...gnd should go to your usb and negative side of battery....the output should go to the other side of your usb and you in should go to the posotive side of your 9v.. and the switch can be thrown in anywhere.... correct me if im wrong but i usually am not..LOL!

3 replies

i"ve connected this charger exactly like it is showed schematic and in real life model too. it is working very well,but regulator may get hot! :( regulator is that side up what is showed in picture at (step 1).sorry if you can,t understand some words,i"m not from USA or UK.

Just take a washer and bolt it to the regulator for a plain and simple heat sink. Preferably aluminum. But other than that you may be able to find small heat sinks in old computers

and thanx for correcting even ,if you are wrong ,but it is nice if someone helps!

Now can you use this to charge the 9v batty also? and if you did what would keep the battery from over charging and exploding? Does any one know how to make a 9v battery charging circuit?

please help me i did a project like this but with a added led and i hooked up everything right and everything works but when i plug my phine into the usb the led goes off and my phone doesnt charge

Will this word with the new Ipod Touch 4?