need for 1.2v to 3.7v dc/dc converter

[younes_ysf]

hello
i need a circuit of a 1.2v to 3.7v dc/dc converter. i have a mp3 player that have usb port. and i want to power this mp3 player with this port with a 1.2v rechargable battery size AA. this mp3 player uses about 40-70mA. so i want to be the output voltage be 3.7 volt and about 100mA. is it possible or not. can somebodi help me.

 

[RadioRon]

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[younes_ysf]

thanks. are there another suggestion?

 

[colin55]

If you want say 50mA out, the circuit will draw more than 170mA from your battery.
Thus 100mA out will take more than 350mA from a single cell. A single 1.2v or 1.5v cell will not last very long when high currents like this are required. That's why it is much better to use a single 3.6v cell such as this:

"Li-Ion 18650 Cylindrical Cell 3.6V 2600mAh - Highest Energy Density Cell on Market"

 

[98formulaLS1]

are you required to use the AA battery? you could use a 3V lithium or 3-AA's.

plus, mp3 players that recharge the batteries through the USB port usually have some sort of battery monitor, which may not allow you to POWER the player with your "USB-batteries" becuase the IC circuitry might be checking for the existance of a battery to recharge.

 

[younes_ysf]

let me explain my condition. i have a mp3 player that its internal battery have been damaged and it takes charge only for an hour. i have have took out its internal battery. i have examined and saw that i can use a external battery that is connected via usb and the mp3 player works anjd just shows the battery are charging but no problem for working.i axamined the current that its use. it was about 40mA to 70mA when the sound is in high and the lcd is on. i have 2 rechargable Ni-Mh 2400mA battery. and size AA and 2 battery in size AA 700mA. i dont want to by another battery and dont want to have complex of this batteris to have 3.7 volt. just wanna use 1 battery. now is it possible? are there any circuit? i like to be as small as it can be. sorry for this long explain

 

[98formulaLS1]

well you should google how to design a "boost converter"

 

[Rob6pt7]

Minty Boost! - USB charger for your gadgets will work fine