Portable Pandora Charger!


GizmoTheGreen

GizmoTheGreen

Active Member
Joined
Jul 27, 2009
Messages
836
Age
34
Location
Tokyo, Japan
What you need:

Hot-glue gun
Soldering iron
Solder
Soldering grease
A few cables
1x LM7805 or similar
1x Heatsink of some kind
1x 100µf 10v+ capacitor
1x 10µf 10v+ capacitor
1x 104 ceramic capacitor
1x USB Female
1x 9v battery connector
1x non-momentary power switch
Optionally 1x led and matching resistor

Now connect it together!


schematic in a bit...

Result:

5v USB charger, charge anything that can charge via usb, on the go!
 
If you don't post quickly we'll know you glued your fingers together.

EDIT: since you edited your first post I can not wait to view the pics when I'm not at work. Sounds like you did a great job!
 
Neat, but don't you think a 9V battery will be exhausted very quickly? They are not designed to provide much current.

I did something similar for my GP2X back in the day.
chargerx.jpg

The voltage can be adjusted with that little pot. Goes form 2V - 5V stepless.
I guess i could reuse it for the Pandora, just need to add the right connector.
 
haha yeah.

but a 9v is pretty small, and not very heavy, compared to 8xAA, or 10 in my case (we didnt have a 9v at home, so i used a bat pack of 10x1,5V AA = 15v, chips runs really hot)
 
It's a nice idea, though the use of a linear regulator is going to provide some potential issues in heat and battery consumption. Linear regulators are generally nice and smooth, but not intended for efficiency. Whereas a switch mode power circuit will convert one voltage to another (albeit not with 100% efficiency), a linear voltage regulator produces the regulated output by simply dumping the excess power as heat.

What this means is that of the 9 volts going into the 7805 here, 5V will be used to power the connected output device, and the remaining 4V will be dissipated as heat via the 7805's heatsink. Basically, that's 44% of the battery's power being wasted; only 56% of the battery is actually being put to the use you want.

That dissipated heat may also prove an issue. If the device you are connecting draws say 250mA, the 7805 has to dump 1 watt of heat (4V x 0.25A). Depending on your projected power load, the 7805 may need to be mounted on a heatsink. The device's own heatsink tab may serve it with currents of around 100mA, but anything above 0.5W will likely require the device to be attached to a heatsink.
 
I'm aware of that Loonie, but local store only had the linear one :)
Still, better than nothing xD

and yes, i will attach a heatsink tomorrow, didnt have any m3 screw + bolt handy

Thank you for the heads up though!
 
right, sorry to hi-jack

but you seem to know your stuff
i got this charger a few years back for the psp, never used it

i could see much more use for the pandora in the car though

craig (i think) said not to use 3rd party chargers

soooooooo...
why would it be bad, i could try to get hold of a multimeter, if its anygood, or ill try and get it open

thanks for any help
 
Im not really sure...
if its a car-12v to psp-5v charger, then i think its okay...

measure the voltage and see if its ok, not too much, not too little.
 
GizmoTheGreen said:
What you need:

Hot-glue gun
Soldering iron
Solder
Soldering grease
A few cables
1x LM7805 or similar
1x Heatsink of some kind
1x 100µf 10v+ capacitor
1x 10µf 10v+ capacitor
1x 104 ceramic capacitor
1x USB Female
1x 9v battery connector
1x non-momentary power switch
Optionally 1x led and matching resistor

Now connect it together!


schematic in a bit...

Result:

5v USB charger, charge anything that can charge via usb, on the go!
Click to expand...
Can a 9v alkaline battery provide much of a charge? Most 9v batteries only have a few watt hours in them. Can it provide the current? Maybe a rechargeable 9v battery would be better (since a rechargeable provide more current). If anything, I think it would better to make it use AA or possibly AAA batteries.

Chris
 
Last edited by a moderator:
Fishbong said:
Neat, but don't you think a 9V battery will be exhausted very quickly? They are not designed to provide much current.

I did something similar for my GP2X back in the day.
The voltage can be adjusted with that little pot. Goes form 2V - 5V stepless.
I guess i could reuse it for the Pandora, just need to add the right connector.
Click to expand...

Why didn't you just wire them as 2 sets of batteries wired in parallel, thus doubling the run time of the standard gp2x?

Chris
 
Last edited by a moderator:
yes, a rechargable is a better idea, and you can make it run on AA or AAA's too, you'd need 4-5 of them though.
I think you could use 3 AA's with no electronics to a usb cable and use that to charge it with 4,5v, even simpler!
No circuit needed.

And now, bed, work tomorrow :)
 
emcp said:
craig (i think) said not to use 3rd party chargers
Click to expand...
He said not to use CHEAP 3rd party chargers. A lot of the cheap PSP chargers you get from ebay (especially shipped from Asia) are of poor construction with questionable wiring. A known good charger should be just fine.
 
Last edited by a moderator:
I'm planning on using a Solio. My only concern is that it'll be so sustainable and efficient that my head may disappear completely up my own ass.
 
christo930 said:
Fishbong said:
Neat, but don't you think a 9V battery will be exhausted very quickly? They are not designed to provide much current.

I did something similar for my GP2X back in the day.
The voltage can be adjusted with that little pot. Goes form 2V - 5V stepless.
I guess i could reuse it for the Pandora, just need to add the right connector.
Click to expand...

Why didn't you just wire them as 2 sets of batteries wired in parallel, thus doubling the run time of the standard gp2x?

Chris
Click to expand...
Firstly, the idea was to more than double the run time, since batteries that are drained slower can provide more total current due to the smaller internal resistance.
Secondly, i wanted adjustable voltage to be able to use it with other devices. Also my father told me not to put rechargeable batteries in parallel as they can discharge each other very quickly if they have different capacities. I don't know how that works exactly, but he's an electronics engineer developing automotive control systems, so i'm inclined to believe him.

BTW i used a switching regulator, the drawback is you have to have a coil and this huge capacitor.
 
Last edited by a moderator:
Ollonk said:
I'm hoping that my car stereo's USB port will be sufficient... But awesome project; I wish I had that sort of skill.
Click to expand...

Its not skill, you could do the soldering after 15 minutes of practice :)
 
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