9v USB Charger





Introduction: 9v USB Charger

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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Please be positive and constructive.




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

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)