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Mobile phone charger for power

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saiello

New Member
Hi All,
May seem like a bit on a naive question but I was wondering if I could use a mobile phone charger (mains adapter) to power a small circuit. The charger is rated at 3.6V, 350mA and my circuit will only be drawing around 50mA. I believe it should be ok but wondered if there would be any issues.

Thanks!
 
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Chippie

Member
But what supply voltage does your circuit require?
Current alone is not sufficient

your circuit may only need 2.5v to operate in which case the charger's output is too high...or conversely, it may require 6volts and is too low.....
 
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saiello

New Member
Hi,
Yes, sorry, the circuit requires 3V-4V, ideally around 3.5V for driving one ( or maybe two ) of those high brightness white LED's, current draw 30mA. I was wondering if there may be an electrical issue with the charger itself if it were to be used in this way for lengthy periods of time...

Thanks.
 

ericgibbs

Well-Known Member
Most Helpful Member
Hi,
Yes, sorry, the circuit requires 3V-4V, ideally around 3.5V for driving one ( or maybe two ) of those high brightness white LED's, current draw 30mA. I was wondering if there may be an electrical issue with the charger itself if it were to be used in this way for lengthy periods of time...

Thanks.

I would check the offload voltage from the charger, also when its lightly loaded.
The lowload voltage could be much higher than 3.6V.:)
 
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BrownOut

Banned
Chargers generally aren't good for powering electronics, because their output filtering is poor or nonexistant.
 

Mr RB

Well-Known Member
A lot of the more recent chargers are "smart" ie they need to detect that the phone is present or they dont work. Then once working they provide specific voltage current etc to suit the phone that they are measuring to complete a charge cycle.

Some even communcate digitally with the microcontroller inside the phone before they work.
 

MikeMl

Well-Known Member
Most Helpful Member
After all the doom and gloom, I say just go and try it. I have recently been using both the Mains and 12VDC input cell phone chargers to power unrelated projects. They have universally been regulated and well filtered. The ones I used had just the simple two-conductor coaxial plug on them, which I cut off. I have never seen one with a uprocessor inside it. :D

btw-I traced out enough of the wiring inside these chargers to be able to modify their output voltage. For example, I needed 5.3V @ 300mA to power an XM Roady radio. I bought a 12VDC - 9V charger for a $1 at a closeout store. Changing one resistor will train this charger to output anything from ~3 to ~10V (this one is a DC switcher)
 

saiello

New Member
Thanks for all the info! :D I'll think I'll get myself a suitable charger and see how it goes..

Thanks again!
 
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