Question regarding creating a USB charger...

[timxirish]

So I think it's common knowledge that the power line in USB is 5v, right?

I'm planning on modifying my DSi LL's power adapter to also have a USB connector like what I did with my DSLite.

The problem is the DSLite's input is (If I recall correct from memory) 5.2v and the DSi takes 4.6v. I felt it was reasonable to assume that giving the DSLite 5v wouldn't damage it, and after a year of charging it via USB, I'm pretty sure it's safe.

However on the DSi, I don't think giving 5v to something that wants 4.6v is a safe decision. I thought maybe if I used a resistor to step the voltage down to 4.6v, it would be safer. But is a resistor really what I want? Or would someone more knowledgeable on electronics recommend using something else instead of the resistor?

Thanks in advance.

[hyper999]

Not sure and I'm sure one of our EE's will jump in here but a diode is probably the best way to drop the voltage here. A diode, when put in series, will drop the supply voltage to the ds by 0.6 volts.

[frenulem - No.5417]

Nail on the head hyper, put a diode in there and it will drop by 0.6V

[timxirish]

Is there any specific type of diode I'm looking for? Aside from light emitting diodes ( :p ), I have no idea what the different types are, or which I should go with. (ie. zener diode)

Also, any specific specs should I be looking for? (or instead, any specs I should avoid?)

Thanks again guys, really appreciate the replies. I'd be more than happy to donate a quality pictorial in return.

[frenulem - No.5417]

Just your regular silicon diode, Zener diodes are mainly used for ac currents and things, if I can pull a part number somewhere I will but right now I'm having breakfast with my dad lol

[timxirish]

Hah, alright, would be much appreciated. Radio shack (ew, i know) or mouser preferred, but i'll take what I can get.

In the meantime, enjoy your breakfast.

[frenulem - No.5417]

http://www.radioshack.com/product/index.jsp?productId=2036269 that should do ya

[timxirish]

Cheers man, I picked one of those up yesterday while I was at work. I'll probably install it tonight or tomorrow (taking crisp pics as I go).

My only concern is that the package claims a voltage drop of 1.6v ("forward voltage drop"; i assume it to mean the same thing?). But the worst that could happen is the DSi will slowly charge or not charge at all. If it's considerably slow, I may try searching around for a "silicon diode" with a 0.6v drop.. I can always change it later anyway.

Bottom line is nothing beats the convenience of being able to charge with USB. I feel pretty damn rude if I take up more than one outlet in a public place, so this will make things easier.

Anyhow, this is what you can expect when I'm finished:
[spoiler]
http://i54.tinypic.com/bfrryo.jpg
edit: looks like I can't post images. oh well.[/spoiler]

I had to trim a little corner of the DSLite's AC adapter's PCB to make it fit, but that's half the fun . I'm half expecting to do the same with the DSi power adapter, but we'll see how that goes.

Thanks again man!

[frenulem - No.5417]

, i screwed up man i was going to put up a silicon diode, thats what i should have sent you

[nEoVaLoR]

You aren't going to use mini usb??? D:

[timxirish]

, i screwed up man i was going to put up a silicon diode, thats what i should have sent you

No worries, if it doesn't work I can fix it relatively easy. Is there a different one you would recommend then?

You aren't going to use mini usb??? D:

Nah, I realize the usefulness of adding mini USB, but the perfectionist in me is holding me back from doing it. I want to keep my case as virgin as possible, only because it's a Japanese import (DSi LL). If I did that, I would have to modify the bottom housing (which is the only housing piece externally different from a US DSi XL).

If I knew I could make a perfect professional cut, then i'd definitely do it. I may also consider it if I can get a Japanese housing replacement. I would probably do a overclocking switch too.

[frenulem - No.5417]

go for the silicon diode, thats the one you need