Intro: DIY USB Emergency Light
Most modern smartphones today has a built in Flashlight App.,And we don't occasionally use it unless we need too.,because it eats a lot of battery juice.,And most smartphone user's today owns at least one powerbank.,as battery back up.,And some commercial powerbank were built and made without Flashlight built into it which are more inexpensive or cheaper than the one with built in flashlight on it.So incase of emergency.,we have to rely on our phones flashlight app that will drain our phone .,Or bring along a flashlight in your packs.That's the purpose of this small project.
An emergency light/lamp that requires low voltage from DC or AC power supply.That can be very useful as an alternative to standard flashlight or lamp.
•this project are commercially available in bulk orders online.
•it cost me nothing to built this project(as i used old stock parts).
•powered by 5vdc
Step 1: Parts and Tools
•1* Super Bright White LED
•1* 18 ohm resitor
•1* PVC tube 20 mm diameter
x 27.5 mm length
• E.V.A foam
•Aluminum foil or equivalent
-to use as reflector
•Black & Red wires(optional)
•Powerbank or an AC USB Mobile charger(to power it up)
•Soldering iron + lead
•Hacksaw or Bread knife to cut PVC
•some other tools that's necessary to make this project
Step 2: How to Make
1•Prepare all the parts & tools needed
2•Cut the PVC and prepare at least 27.5mm length of PVC(that's all we need for this small project).
3•Cut the e.v.a foam according to the inner diameter of the pvc you are using-as we need to prepare a Bezel for LED & USB Male plug.
4•For LED Bezel-get an aluminum sheet or aluminum coated paper found on cigarrete packs.
5•Cut the aluminum sheet(use as Reflector for the LED).,according to the diameter of EVA foam you cut.(Bezel for the LED).And glue the aluminum sheet using elmers glue or equivalent.
6•Insert the LED on the bezel with aluminum reflector.
7•For the USB Male-Make a slot on foam (the one to be use as USB male bezel).Then make sure the USB male plug will fit on it.Insert the USB Male on it.
1•Solder the 18ohm resistor on the positive side of the USB male and solder the other end of the 18 ohm resistor on the positive side of the LED.(use red wire if needed)
2•Then solder a black wire on the ground side of the USB Male and solder the end of black wire to the negative side of the LED.
3•Test it by plugging it on your powerbank or on your wallwart USB mobile charger.
•Parameters used here is:
5vdc as input voltage is used here which is commonly supplied on Powerbanks and USB mobile chargers.
••Adding Switch on this project is an option to the maker.,Since my powerbank had On/Off switch.,That's why i skipped adding one.
•••ALL THE GUIDES ON HOW TO MAKE THIS SMALL PROJECT CAN BE SEEN ON IMAGES•••
••••You may use other color variants of LED - the resistor value will be changed accordingly.,See the What type of LED to use ••••
Step 3: Test
Test...test and more test on different powerbanks if needed.(optional)
Step 4: What Resistor to Use?
LED resistor calculator
•Manual Resistor Calculations for this small project:
R=(V1-V2) / I
Volt 1 = Supply Voltage
Volt 2 = LED Voltage
I = LED Current ( Amp )
R = Resistance (Resistor Value)
• Resistance=Volt1 - Volt2 / Amp
R= (5 - 3.5) / 0.09
R= 1.5 / 0.09
R= 16.66 calculated resistance
I picked and used 18 ohm Resistor as this is the one i have in hand and this is the nearest higher rated 10% resistor
What type of LED to used?See image if your using Low Current or Standard LED.
Step 5: Schematics
Simple and very basic schematics guide to follow.
Step 6: Powered on AC or DC
You can power it using USB Mobile charger as night lamp for reading if powerbank is not available.
Step 7: Result
The result was great.,i was saved from spending to buy a pocket sized flashlight,a flexible flashlight/lamp that i can power through DC or AC anytime.A compact size ,economical emergency light that's easy to carry and very easy to make.
Hope you enjoy reading and wish it helps those who love to build using LEDs.