Introduction: Add Power Cord to Battery Operated Night Light
I think the battery's in these dream light things run out way to fast. so we are making our own power source to plug into the wall out of an old phone charger.
Step 1: Power Supply
we have to check the polarity of the cords coming from the power supply. you can see from the picture that we have a negative symbol next to a voltage reading which tells us that our polarity is reversed and our voltage is just a little high (.5 over) but not enough to cause any problems.
Step 2: Ready the Power Supply
first make sure you unplug the power supply and then cut off the end of the power supply and save for later project. now strip the existing wire from the power supply to expose the copper
Step 3: Connect to the Light.
this particular night light has a place to plug a power supply directly into the light itself. we do not have the plug that fits into the light so we're going to have to make our connection manually. we use the screwdriver to push the ends of the wire into both the positive and negative, then tighten. In the wire at the towards the end to prevent from pulling the wire out. make a little slot in the inside so that the wire can go through without getting hurt by the case.
Step 4: Test
plug into wall outlet and make sure it does not blow up it should work better than it ever has.
7 years ago
Cool lighting system. The only thing to keep in mind is that a phone charger output 5 volts. A lot of LEDs are only designed to run on 4.5 volts. It you put too much power into the LEDs it can cause it to burn out faster than normal.
Reply 7 years ago
Could we add a resister to extend the life of the led? if so what value should be used?
Reply 7 years ago
You could. But first you would need to know how much current it uses. Then you would know how big of resistor to use. You could just use trial and error until the battery terminals measure 4.5 volts, but you would need to be sure that the resistor is rated for high enough wattage so that the resistor does burn out.
A simpler alternative is to use a diode. In most operating ranges a diode will drop the voltage by 0.6 volts. That is just about perfect to turn 5 volts into 4.4 volts for the LEDs. Any regular silicon diode (1 amp or higher) will do the trick.