Mobile Charger

What?

Please don't be shy about providing a complete description about what you want to do. What type of thing? The generator? the mobile charger? What kind of mobile charger? 3 volt? 6 volt? 12 volt? What input does it have? AC or DC? 12 volt? 110 volt? 115 volt? 220 volt?

hello sir,

i have 5 volt ac (open ckt voltage)which is obtained across a generator and current is 3ma when connected across 1500 ohm resistance. Now i want to use this for charging mobile that is convert this 5volt AC into DC 3.5 volt. is it clear sir ?

thanx...

Well, it's gotten somewhere at least. You have 5 or 6 volts AC from a generator that can provide 3mA when connected across 1500 ohms. You want to use this to charge your mobile which operates on 3.5 volt dc.

Let's see...according to Ohm's Law, 3mA across 1500 ohms gives us 4.5 volts. So we started with 6 volts, got down to 5 volts and now we're down to 4.5 volts.

Seems to me your generator is a very low power device. For comparison, my mobiles charger outputs 5.7 volts dc and can supply 800mA of power. My mobile's battery is also 3.5 volts so I guess my mobile has a circuit that drops that 5.7 volts down to 3.5 volts while it's charging. My guess is your mobile is, basically, the same.

I don't what kind of generator you have but it sounds like doesn't have a very stable output. I don't know what brand and model of mobile you have. If it's a new or expensive model, I wouldn't attempt to do this. You might damage your unit and there'd be several fingers pointing to the pointy eared member of CR4!

Yeah - 3mA is not much current. You'll be charging your phone for days.

Go to a lawn mower shop and ask them for a bridge rectifier it is a little square device with a mounting hole in the middle,and 4 tabs on the 4 sides of one face. Two of the tabs are for the AC input ,the other two tabs are for DC out. Hook it up to your generator and see what you get for a voltage out on a DC scale on your voltmeter. If this is suitable for your purpose, then you are in business,if not your not out much and no further behind than when you first started asking questions here.

Hilltopper,

I had thought of the bridge rectifier but didn't offer it immediately until our friend made a decision about going through with it or not. Besides, a bridge rectifier produces pulsating DC that his mobile may or may not like. Of course it's a simple matter to put a capacitor there to clean it up. If he wants to try it then, I say, good luck.

I still don't think that his generator will be up to the task. It sounds underpowered and produces unstable voltages. He could end up damaging his mobile, but like I said, it's up to him.

All the chargers with well renowned Manufacturers, like Nokia have very simple & cheap chargers: just one diode connected in series of 6VAC [nominal from a 2W stepdown transformer 220V/110V to 6V].

Some of the Manufacturers now supplying 90V to 250VAC , using digital-circuit.

Just connect a diode [or more precisely a bridge-Rectifier] & enjoy

hi.................

lets me help you in your problem.

i think that if you need to charge your mobile by 6 volts ac power supply you have to use what we call ac to dc convertors, they are of many types and of many usages, so you have to be carefull of what electric circuit you should use because if you use a small micro-chip as aconvertor your current may be so harmfull and may cause damage fo your ICs.

thanks to participate you...................

You are out of luck.

My cell phone requires 1 amp!

Your AC is very low power and you need far more to charge a mobile phone.

repeat your experiment on the generator with 5ohms.

3 MA across 1.5k resistor means you have already dropped .5 volts. By the time you add 2 diodes for full wave rectification you are down another 1.4 volts. Peak open circuit generator voltage will be about 7 volts, at 3 MA that will be about 6.3, minus the 1.4 and the peak rectified will be about 5 volts.

But still no power to work with!

An ordinary bicycle dynamo supplies about 6V at 500 mA: what are you using?