i planning to make a handphone charger using a 12 volt battery.... now, i should make a regulator to transfer 12 volt into 3.7 volt DC.. anyone know the scheme of "Regulator 3.7 volt dc"?
Or, anyone know where i can find the website that full of electronic scheme ?
2007-06-07 15:13:34 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
The nominal 3.7 volt Lithium Batteries get charged by a 5 volt "wall wart" and the cell phones have the safety circuitry to prevent over-charge... since over-charging a Lithium battery can start a fire.
so you need to make a standard step-down voltage regulator.
But... its cheaper to buy one of the ready-made automotive chargers than it is to make one yourself.
2007-06-07 15:18:50 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Charging a battery is a lot more complex than most people realize. It's real easy to 'overcharge' many of the smaller batteries. There are, however, some very good 'battery charger' chips out there. Google on 'battery charging semiconductors' and you should get a few hits to start on.
Doug
2007-06-07 22:21:18 · answer #2 · answered by doug_donaghue 7 · 0⤊ 0⤋
A simple regulator circuit can be designed using a LM317 chip. The datasheet for this IC explains how to obtain exactly the voltage you need.
Remember, this is only a regulator circuit. You need other control circuitry to protect the battery from overload.
2007-06-08 01:29:18 · answer #3 · answered by Kenneth 3 · 0⤊ 0⤋
Assuming you are suppling power to the phone and letting it's charging circuit take care of the details involved in actually charging the battery, I second the idea of buying a commercial auto adapter.
2007-06-08 03:29:57 · answer #4 · answered by tinkertailorcandlestickmaker 7 · 0⤊ 0⤋