The Ultimate Household/Emergency Flashlight System

This flashlight and base work together to create the ultimate household flashlight system! The base makes a soothing night-light, keeps the flashlight charged, and will turn on a high-brightness LED if a power outage strikes. When the flashlight is removed from the base, it becomes a super-bright lantern to help you find your way, and will also work as a battery powered desk lamp.

Even though it is designed to help in a power outage, it also works as a perfect around-the-house flashlight. It is especially useful that you can set it down and bend the light to wherever you need it, and keeps your hands free. The base makes recharging easy and leaves the flashlight always ready to use, no need to mess with batteries.

It's also cheap and very easy to make!

How it works:

A wall-wart transformer is constantly plugged in and connected to the base. A PNP transistor has its base connected to the power in from the wall, and the voltage from that turns the transistor off. When it stops getting external power, the transistor is turned on and sends power through a connector to the flashlight. This turns on the flashlight's high power LED on a low power, letting out plenty of light to find your way but conserving the batteries. If the button on the flashlight is pressed, it goes to full power.

Now let's get started!

Step 1 Materials and Tools

Here is what you should have to build this project:

Materials:

• Small piece of prototyping board.
• Wall-wart transformer with a voltage of at least 7.5v. Low current is fine but you might want more (500ma) if you will be running the flashlight at full power while it is connected to the base.
• 4x AA rechargeable batteries (I used Energizer 2450mah)
• 4AA battery holder.
• Small heat sink for LED with heat sink grease.
• Insulated wire, for the board and for the flashlight.
• Think, solid wire to support the bendable neck of the flashlight.
• A small connector set with at least three wires, this hooks the flashlight to the base.
• Small zip tie, I needed one for the wall wart but you might not.
• Milk carton; I cut a piece off to cover the base and diffuse the night-light LEDs.
• Q1: LM317T adjustable voltage regulator.
• Q2: A PNP transistor. I used a TIP42
• D1: Pretty much any diode (not zener). I used a 1A 400v rectifier diode.
• S1: A small PCB mountable switch. You could use a large, non-PCB mountable one if you attach wires to it, it's just not as pretty.
• S2: A larger, non PCP mountable push-on push-off button. You could use a small, PCB mountable one, but it will be harder to use and might not be able to handle the current.
• R1: For your LED(s). Will vary with what LED(s) you use, I used a 10 ohm 10 watt. If you have the right parts (I didn't), it is recommended you build something like this.
• R2: 1k ohm resistor, for the transistor.
• R3: 10k ohm resistor, for the transistor. If you want to have the light come on brighter when the power goes out, lower the value of this resistor.
• R4 and R5: will vary with what LEDs you use for the night-light. Mine were 82 ohm.
• R6: 560 ohm resistor, for the regulator.
• R7: 2.2k ohm resistor, for the regulator. In combination with R6, they make the regulator output around 6 volts.
• LED1: The high-power LED in the flashlight. You could use a bunch of normal ones if you wanted to, just make sure to use the proper resistors.
• LEDs 2-5: The four LEDs for the night-light on the base.

That may seem like a lot, but it really isn't that much.

Tools:

• Soldering iron with solder
• Helping hands (helpful but not needed)
• Hot glue gun with glue
• Wire cutter/stripper
• Scissors
• Pliers

Once you have everything gathered, lets move on!

Comments

[batman96]

Could you post a schematic that uses normal batteries, and just uses the wall wart power to sense the presence of power, and to run the light if you want to switch it on when the power is on, I was thinking about using something like this with regular batteries for our wireless telephone base, when the power goes out it would switch to the batteries, like a mini UPS for computers, could you post a schematic?

Batman96

[dark sponge]

For that you can probably take out the voltage regulator, the resistors and diode connected to it, and the middle pin of the connector out and it should work. I'd like to see it if you make it, good luck!

[batman96]

Thanks, I will try it when I get a few other pressing projects done.

[acoleman3]

funny how some of these components look like they came from thecustomsabershop.com. especially the rebel star LED and the PCB. nice idea to have these plans available.

[acoleman3]

no actually....it looks like most of the SEOUL P4 LED blade kit now that i think about it. the switch looks like its from radio shack since teh kit only has a momentary switch.

[dark sponge]

I got the LED (and pretty much everything else) from Mouser, I could look up the model number if you want. But you're right, the switch is leftover from the days when I would still shop at Radioshack :-)

[cdousley]

i love it after i get done with a few projects i definitely want to make this

[dark sponge]

Thanks! Send pictures when you do!

[cdousley]

one question does it automatically turn back on after the power turns on?

[dark sponge]

Yep! It also charges the battery back up until it's full.

[cdousley]

WOW! and FAST RESPONSE!

[dark sponge]

You're welcome! :-)

[hg341]

love how the chargeing base is a night light you need to work on a case

[dark sponge]

Thanks! Personally I don't think it needs a case, but I'm sure a lot of people would. If you make one, please send pictures!