Electrical Circuit Stuff +3REP ~ Warning, science content!

[Chippiewill]

Ok, I am currently working on an iPod charger (A USB charger in fairness) and it consists of 6AA batteries in a series. I need to somehow make it restrict the voltage down to exactly 5V and the Current (Amperage) down to 500mA or less. Info: Batteries Combined = 9V, 1500mA roughly, however a dynamic solution (Not just a % reduction due to battery power reducing over time) is preferred for Amps.

I know there are lots of online tutorials however they use different combinations (Such as two AAs or a 9V Battery). So could someone give a suggestion of Diodes and Resistors e.t.c.

Thank-you

[Johno]

Er, not exactly sure about any of this but just thinking about some general electronics stuff, this should work...

Current resistance of the circuit would be 6 ohms, and to get it to 5V and 500mA, the resistance would need to be 10 ohms. So adding a 4 ohm resistor in series should bring the voltage and current down to what you need.

edit: a friend says you should look for a component called a voltage regulator, he says it will give you of a more consistent voltage but he is not sure about the current.

[Tomm]

As stated above, just use a voltage regulator. No need to worry about the current as the current is set by the load (i.e how much the iPod/other usb device) wants to draw from it, limited by the current of the power supply.

[Chippiewill]

Ok thanks, I will have a look on the Maplins site and look for a Voltage regulator...

[Chippiewill]

Hmmph, all the guides that I have seen say I need a Zener diode and 100-330 ohm resistor...

[Chippiewill]

Sorry for trip post , I just missed the last edit

Ok, I have had a good read at the Hack-A-Day article,

It Says that:

The Zener diode keeps the Voltage at 5.1V
The 100 ohm resistor stops the circuit from short circuiting

However I have extra Current so would I need a stronger resistor?