I'm Manuel and welcome back to another project regarding green energy. Today, we are going to make a tiny little hand crank flashlight from an old DVD player and it can be faithful companion in emergency situations. I know it sounds impossible but it isn't, and i'll demonstrate to you in a minute!
Let's get started!
Step 1: Materials
For this project you will need to buy or held the following stuff/tools:
- Obviously an old DVD player from a computer
- Set of screwdriver (different DVD player have different screws)
- Dremel multi tool (otherwise you can use an hacksaw and sliding cutter)
- Piece of copper tube (10mm diameter and 3cm height)
- About 10cm of 3mm diameter copper wire.
- Soldering iron and solder wire
- Hot glue gun
- Step up voltage converter
- 4 pieces of small wires
- 2 leds
- A small piece of PCB
- 50 ohm resistor (if you don't have it, you can use an higher value but the light will decrease)
Step 2: Basics
Before starting to make it, let me explain better the role of all the components and how the flashlight we are going to build works.
Basically an Hand Crank device transform human power in electrical voltage that could be used for different applications such as emitting light through a led, power a radio or charging your phone.
The main components of this flashlight are:
- DC Motor: every dc motor could be used as a generator. So basically, if we apply a voltage between its 2 pins (positive and negative) its shaft will rotate but the motor can also convert human power (through rotations) into electrical power that can supply a circuit. To increase the output voltage, the motor is always connected with a system of gears that increase its rpm. The more the rpm, the more the output voltage.
- The Step Up circuit: it's used to increase the output voltage of the motor in order to use it. The circuit I used is able to produce a 5V output from a minimum of 0.9V.
- Two LEDs: transform electrical current into light. I used common 5mm LEDs, 3V and 20mA forward current each. I connected them in parallel so each LED receive the same circuit voltage and the total current consumed is the sum of the 2 LEDs current (20mA+20mA=0.040A).
- A Resistor: Its main role is to limit the current flowing into the 2 LEDs preventing them from burning. I calculate the right value using Ohm's Law
(5-3)V= R* (2*0.02A)
Step 3: Take Apart the Dvd Player
Now we are Ready to begin the project!
I started by removing all the four screws from the upper side of the DVD player and, as a result, it opened up.
Now you will see a big green circuit board with a lot of small components soldered on it but we don't need it so I remove it by unscrewing all the little screws. Once I have done it, I also took out the small system composed by a little stepper motor that moves an optical system of lens. Finally I was able to see the plastic rectangular frame with a DC motor and some pulleys and gears on one side.
Using an hacksaw or a Dremel tool I cut the frame section with the motor from the rest of the plastic frame.
At this point, I carefully removed all the plastic in excess from the system.
Step 4: Assemble the Hand Crank Motor
Once we get rid of all the useless plastic around the motor and the system of gear, we are ready to make an arm connected to the gears in order to easy crank the motor.
The arm is made out of a 10cm long copper wire bended to one end to make an handle. The most difficult part was to make a connection between the last gear and the arm. I tried to figure out the simpliest way to do that and I came up with a piece of copper tube. it is glued on one end to the gear and has a little hole from side to side at the other end. At this point, I insert the wire into the hole in the copper tube and, with a 60W soldering iron, I soldered it in place. If you don't have a powerful soldering iron, you can simply glue the two components with some epoxy glue.
Now I had a full working hand crank motor!
Step 5: The Circuit
At this point, I tested the output voltage of the motor and surprisingly... it was only 2 miserable Volts!!
I know, they seems to be unusable but they are enough to power a flashlight with some help.... a step up circuit.
It is a little tiny circuit that basically increase the output voltage of the crank system from 2V to 5V and give us approximately 200mA of current. it has 3 pins: the positive input, the ground and the positive output.
First of all, I soldered two pieces of wire from the two terminals (positive and negative) of the motor to the relative pins (positive input and ground) of the circuit.
At this point I soldered the two LEDs and the resistor (according to the schematic) on a small PCB to maintain the things in order.
Last thing to do is to connect the positive output from the circuit to the free end of the resistor and the negative pin of the circuit of the cathode of the two LEDs.
Step 6: Results
So the project is finished! I tested the flashlight in the dark and it produces a decent amount of light! I'm really happy the way it tourned out!
As I said in the Intro, The aim of this tutorial is to show you how to make a tiny flashlight from scrap that can be really useful in emergency situations such as blackouts. It has no batteries or capacitor so you have just to pick it up and crank and it will never abandon you!
I want to thank everyone who read and follow my project and if you have any doubts or questions please leave a comment! I really appreciate it and I like to help those ones who decide to make their own hand crank flashlight!
See you soon with another DIY project!