How to power light bulbs with AA batteries

Question

I want to know if there is a way to power multiple (very small) L.E.D lights with only a few AA batteries. And i need a way to do it using ONLY household items. it's for a project and i cant go out and buy anything except for the bulbs and batteries. :P i know it's weird. but can i use the cable for a pair of headphones to connect them or something???? help please

Answer 1

Being that you have to light up two different projects, do it this way:

You will need 8 AA batteries.  You will hook them all in series (make 4 groups of two, and connect the ends together using aluminum foil.  Wrap the whole thing together with rubber bands to hold the connections tight, and wrap it up with duct tape).  

Now you have a 12 Volt supply that will power the taillight bulb directly.  For wire, you can again use foil, or the wire that is normally used to hang pictures. Connect one end of the bulb to the + and the other to the - of the battery pack, and there you go.

For the LEDs, it is a bit tougher.  Your 12V power supply will still do a great job.  You can hook 4 LEDs in series (twist the leads together, but remember to keep the polarities correct, + to - for each connection).  Now you need a resistor to limit the current.  I suggest that you use a night light bulb (one of those with a small s***w base) to put in series with the LEDs.  This will limit the current to something safe.

The big light bulb suggested by one of the other respondents is a bad idea, because the cold resistance of an incandescent bulb is about 1/15th of the hot resistance, so his calculation is way off.

Answer 2

Batteries have about 1.5 volts per battery.  An LED requires about 3.2 to 3.6 volts to power it.  Three batteries in series will be 4.5 volts.  That is too much voltage.

You need to current limit the batteries.  Usually, you would use a resistor but you say you can't get a resistor.  If you can get a resistor and the LEDs are 20mA LEDs the resistor would be about 50 ohms.

Without a regular resistor you could hook a 150 watt incandecent light bulb in series with the batteries.  It is about 80 ohms.  The light bulb won't light up - but the LEDs will.

Be sure to connect the LEDs with the correct polarity.

Answer 3

yes u could use any type of conducter but i think i would look toward using aluminum foil to cary the current, and thats what these little flash lights with multiple bulbs in them have is aa batteries

Answer 4

well cell phone batteries charge those lights, but as far as AA batteries, a lot of remote controls have night lights so that's one way.