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Can I use a cell phone battery on a mp3 player?

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sf1

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Hi, i am thinking of making a circuit that will use a Li-ion 3.7v battery and use it on a mp3 player that originally uses an AAA battery. If i use resistors in the circuit to drop the 3.7v to 1.5v will the power dissipated in the resistors be significant? Will the Li-ion battery actually last longer than an AAA battery? Also do I need to concern about the currents?
 

sf1 said:
Hi, i am thinking of making a circuit that will use a Li-ion 3.7v battery and use it on a mp3 player that originally uses an AAA battery. If i use resistors in the circuit to drop the 3.7v to 1.5v will the power dissipated in the resistors be significant? Will the Li-ion battery actually last longer than an AAA battery? Also do I need to concern about the currents?
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depend how much curret unit draw. but you always waste energy 1.5 Volt -> 3.7 Volt to heat and only using 30-40 % of batterys total energy capacity if only using linary regulator (or resistance if current is very constant with using) to take down voltage.

but 3.0-4.0 Volt is very attractive if you want more power to eraphone amplifier for louder soundlevel without clipping...

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possibe to find couple of circurits to convert 3.0-4.2 Volt from LiIon-battery to 1.5 Volt without so much loss.

See maxim, Analog device, and nationa semicontctor etc.
 

If you had to ask me, I would have to say SMPS although more complicated than linear voltage regulators. They are more efficient.

Sputnik :idea:
 

Hi,

You can get a single battery, I am not sure if it is 1.5V though.

I have seen these loose batteries being sold in quantity of three pcs.

I can check which cell phone uses them if you wish.

Bye.
 

You can try to make a switching mode power supply(DC - DC convertor) by yourself with chip comes from ST or Linear Technology and few passive components. It's effiency is can reach up to 85% or even higher.
 

oh heck, just stick lots of 1n4001 type diodes inline with the +v to drop the voltage.

Each one should drop 0.6v

Much easier than building a psu.
 

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