Psu Requirements


sixxie

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Well, I received my GP2X today, and for as long as the batteries held out I've been pretty happy with it. But if I don't want to use batteries?

ADAPTER INPUT: 3.3V 1A

1 *amp*?! Wow. I mean really. Wow. My 300mA regulated supply needs an upgrade ;)

Anyway, building dev tools now, so expect GP2X support in XRoar not long after I'm next able to power up ;)
 
well, most power adapters put out ore voltage and amperage than a system usually needs, like psone adapters but 7.5 at 3 amps but the psone can go on 7.2 at about one amp. so i imagine 3.3v @500-700mah would run a gp2x, from what ive read it draws about 500 so 1 amp is about double the actual draw, not a bad thing but not needed
 
I went into a Radio Shack today (or rather, "The Source" as they're now called in Canada) to pick up a universal power adapter.

I found a universal "Digital Camera" adapter that can output 3.3V, at up to 2100 mA.

When I asked a salesperson if that would do the trick, he cautioned me that game units are often extremely sensitive about power requirements, and that not using an official adapter from the device manufacturer could fry it.

Does anybody know if there is any truth to this? Or should a universal adapter work perfectly fine?
 
I don't know how many universal adapters you'll find that will do 3.3V (although 3.0V might work OK), the biggest worries are making sure the polarity is correct, and that the voltage isn't too high. Of course, that's just to make sure you don't fry the GP2X - you'll need to make sure the adapter can supply enough current if you want it to actually work (apparently 500 mA is the average draw, but I'd imagine it could spike to 750mA or maybe more, so if you can find a 1A 3.3V adapter, that'd be the best way to go).

The other tricky part is some adapters have poor voltage regulation - they might output 5V or something similar at low load, and only 3.3V once it's outputting more current. It wouldn't hurt to test the output voltage on a volt meter before you plug it in, especially if the adapter is rated for more than a couple amps. The camera adapter you found is probably fine as long as it's got the right connector and polarity. Cameras have an extremely wide variance in their current draw depending on if the LCD is on, and if the flash is charging, so that adapter should give a stable 3.3V at any current draw.
 
I can't find any universal adapters that to 3.3V. I bought a crappy £10 universal adapter from Maplins today, claiming to be "1000mA Unregulated", and it *sort of* works. The screen is incredibly flickery, far worse than anything I've seen when running on nearly-dead batteries, and a few times now the initial dark grey GP2X screen has shown up as a flickering mess (although the unit then goes on to boot & work normally).

The adapter should be outputting plenty of current, although I haven't tested this. The problem is, if anything, either low voltage, or fluctuating voltage (due to the "unregulated" adapter). I did briefly try upping the voltage, but all I got when I turned my gp2x on was a bright white screen for an instant, then it turned itself off again - I was so terrified I'd bricked it! However, after I put the voltage back down, luckily the unit came straight back on as normal. Such behaviour is dangerous and irresponsible, I know, but I thought it'd be safe since the unit had all the symptoms of being underpowered, and I wasn't even upping it to as high as 4v (assuming the dial on this adapter is a standard pot - that's probably where the danger lies :) ).

I'm going to be cheeky and take the adapter back, claim it wasn't the correct type - luckily it just came in a cardboard box, no seals to break. :) I already have some rechargeable batteries, but they don't last very long in the unit (only 1300mAh); I can afford to wait until the official adapters are released. I'd recommend that anyone who has any kind of doubts should do the same.

I bought the adapter after someone posted in another thread that it had helped them to upgrade the firmware on units that wouldn't flash when running on batteries - I can safely say that if you get flickering and other odd behaviour out of your adapter, it won't help in the slightest when it comes to flashing.
 
I'm using a multi-voltage regulated plug pack that supplies 3V at up to 1500mA and it works perfectly. I got it from the Australian equivalent to Radio Shack (Dick Smith Electronics).

There are simply four things to look for in a power adaptor:
1. It must supply a regulated voltage, whether it is 3V or 3.3V does not matter.
2. It must supply at least 500mA. The more the better.
3. It requires a 2.35mm (outside)/0.7mm (pin) barrel plug.
4. Must be able to make the tip (centre) of the plug negative polarity.
 
See how those plugs have two pins on them to connect to the cable? That means you can connect them either way around. That is, centre positive or centre negative. Mine has the same plugs.
 
I just tested two of my power supplies. The first is for my Neuros mp3 player and it tested at ~12V with center being positive. It is rated at 9V 800mA. The second is for my computer speakers, which tested at ~12V with center being negative. It is rated at 9V 700mA. I couldn't find anything on the PSU themselves to indicate the polarity. I also tried reversing the plug to see if that would reverse the polarity ... it didn't. I guess it's smarter than me.

Edit: I found the symbol that indicates the polarity on another thread. I was looking for words on the unit to say that.
 
I have a power supply that seems to satisfy all the requirements:
3V regulated, max 1A, right plug and possibility to switch polarity.

However, when I stick it into the gp2x and turn the unit on, all I get is the initial white/pink-line screen. Even waiting up to ~5s, I don't get the first boot-up screen, instead the white/pink lines just seem to increase in contast a bit.

Anyone know what could be wrong? Possibly the power supply just isn't regulated well enough or doesn't supply the current that it's supposed to. Unfortunately it's very difficult to measure the voltage under load, so it's hard to tell for sure.

Any advice?

/Khell
 
slygamer posted on Dec 1 2005 at 11:54 PM said:
I'm using a multi-voltage regulated plug pack that supplies 3V at up to 1500mA and it works perfectly.

Me too (3V, 1400mA and works fine)
 
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