Hand Crank/Wind Powered Charger

[Mohamed Najiullah]

People might have seen my other threads..So i've some more basic questions..

I'm trying to make a solar cum handcrank/wind dynamo cell phone charger...

As Mr.audioguru kindly told me, a crank/wind dynamo generates all kinds of voltages ranging from 2V to upto 8V..

So i need a boost/cut power supply regulator IC circuit.. Any ideas on what i could use?

And i'l also like to add that i'm a beginner in electronics and therefore dont have much idea about this...

 

[Mohamed Najiullah]

I did a bit of googling and found out these ICs..

But i dont know if they'l work under constantly varying input voltage and currents...

**broken link removed**

**broken link removed**

 

[Hero999]

Both will be fine as long as the input voltage is above 1.2V and below the output voltage.

You'll to put a large capacitor and possible a diode before the input if you're powering it from a dynamo.

 

[Mohamed Najiullah]

Both will be fine as long as the input voltage is above 1.2V and below the output voltage.

You'll to put a large capacitor and possible a diode before the input if you're powering it from a dynamo.

How do i make the IC give a constant 5V? It says the o/p can be set from 1.2V to 14V but what happens to the current? Will it reduce proportionally?

 

[Hero999]

Yes, the input current goes down as the voltage is increased.

The datasheet should show you how to calculate the required resistors for the desired voltage.

 

[Mohamed Najiullah]

You'll to put a large capacitor and possible a diode before the input if you're powering it from a dynamo.

How large should the capacitor be? Is that in the data sheet too?

 

[Hero999]

It really depends on how much ripple there is on the power generated by the dynamo which doesn't produce steady DC, but DC with ripple. If it's a three pole motor, the ripple frequency will be six times the rotational frequency and will look like the output of a three phase bridge rectifier but will be a bit more spiky.

I would choose 470µF electrolytic capacitor with a 100nF ceramic capacitor in parallel and increase it, if there are any problems.

 

[Mohamed Najiullah]

Do I need a battery charger IC to detect when the cells are completely charged and stop the charging?

If yes, can u recommend any such ICs?