Power Supply


wyefye

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Joined
Nov 16, 2005
Messages
124
I was sitting here reading thru some posts when some guy said that batteries that do not supply enough power will cause colored lines on the screen.

Taking this into account, i bought a radioshack 700mA 3 volt psu, and when i turn it off and back on a second or two later, it does this. Just curious to know what the recommended mA's are for the gp2x running on a Psu, Not batteries.

Would this also take care of flicker issues if the mA was increased.

wf.
 
wyefye posted on Dec 7 2005 at 12:46 PM said:
I was sitting here reading thru some posts when some guy said that batteries that do not supply enough power will cause colored lines on the screen.

Taking this into account, i bought a radioshack 700mA 3 volt psu, and when i turn it off and back on a second or two later, it does this. Just curious to know what the recommended mA's are for the gp2x running on a Psu, Not batteries.

Would this also take care of flicker issues if the mA was increased.

wf.

I run mine at 1200mA and 3v and it works just fine. I think the PSU should be 1000mA (1 Ampere) at least.

Hope this helps.
 
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wyefye posted on Dec 7 2005 at 06:46 PM said:
I was sitting here reading thru some posts when some guy said that batteries that do not supply enough power will cause colored lines on the screen.

Taking this into account, i bought a radioshack 700mA 3 volt psu, and when i turn it off and back on a second or two later, it does this. Just curious to know what the recommended mA's are for the gp2x running on a Psu, Not batteries.

Would this also take care of flicker issues if the mA was increased.

wf.

do the coloured lines go away or does the system hang?

it is normal for the lcd to take a second or two to get started after just switching off-on.
 
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To wyefye:
Amperes indicate how much current is going though the unit. The basic rule is I = U/R (for DC). U (voltage) is provided by the batteries and R (ohms) is a factor determined by the GP2X (and its work load etc). These results in X amps. As we don't know R there's no way you can calculate I. However you can measure it. I have a lab-power supply which can be set as voltage limited and then indicates how much current is flowing. (It can go up to 3 AMPS so that should be more than sufficient.) As soon as I get my hardware (expected Wednesday) I'll connect it to my PSU and set it to 3V and check how much current is flowing.

To FusionSamus: What do you mean by: "I run mine at 1200mA and 3v and it works just fine." On a PSU only I or U can be fixed as they are depended on each other (I = U/R). (Both can be limited, but you can hit only one limit at a given time.) Do I correctly suppose that your power supply is set to 3V and gives 1200mA max? If so that does not mean that there actually is 1200mA flowing.

Some general notes:
El Cheapo power supplies never give out the voltage they specify. Duty-free they usually give a too high voltage and loaded they usually give a too low voltage because the voltage drops when they power supply runs into its natural current limit.
It could very well be that the GP2X works a lot better on a decent PSU than on chargeable batteries because chargeable batteries provide 1.2V instead of 1.5V. Also the batteries might not be able to give sufficient current. In that case you should measure a voltage drop.
 
Teun posted on Dec 7 2005 at 01:54 PM said:
To FusionSamus: What do you mean by: "I run mine at 1200mA and 3v and it works just fine." On a PSU only I or U can be fixed as they are depended on each other (I = U/R). (Both can be limited, but you can hit only one limit at a given time.) Do I correctly suppose that your power supply is set to 3V and gives 1200mA max? If so that does not mean that there actually is 1200mA flowing.

It is a 1200mA max, but the voltage and polarity (center negative vs. center positive) are switchable. I have read that the GP2X actually draws about 1000mA of power.

Just my $0.02
 
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successfully using an inverted SONY MD psu, 3V 500mA :)


1000 would give me more chance to succeed some firmware flashing or whatever? :D
 
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