Instructables
Picture of Emergency spin-it LED flashlight
Introduction

In emergency a small light source is a must. You may need it to find a more reliable light source like an operational flashlight. This flashlight is built around a super capacitor and a DC motor. Super caps can store up energy fast and release it slowly. These features plus their compactness make them so useful to build emergency flashlights. One can say: Hey, there are quite a few “shake-it” and “pump-it” models available at reasonable prices. That’s true, but my flashlight is a bit different. 1- minute finger spinning gives 5-minute lighting. You may opt to charge this flashlight with a string loop.
Time:  1 hour
Cost: low
Difficulty: easy
 
Remove these adsRemove these ads by Signing Up

Step 1: Materials and Tools

Picture of Materials and Tools
Materials and Tools

You need:
1. A small plastic bottle. Mine is a container for vitamin C pills. It is large enough to accommodate a DC motor and other parts.
2. DC motor. Mine is a 9V motor salvaged from an old cassette recorder.
3. a short length of insulated wire.
Electronic parts: 1 super capacitor (1F/5.5V), 1 super bright 5mm white LED(50cd), 1 – 24 Ohm/0,25W  resistor (red-yellow-black), 1 Schottky diode (1N5819), a micro slide switch (3-pin).

Tools:

Wire cutters
Tweezers
Soldering iron
Drill and drill bits (optional)
Solder

Step 2: Schematic

Picture of Schematic
Schematic

There are only 5 electronic parts : a super bright  5mm white LED (50cd), a resistor (24 Ohm), a Schottky diode (1N5819), a super capacitor (1F/5.5V),  a micro slide switch (3-pin). The resistor limits the current flowing across the LED. The diode prevents discharging across DC motor’s windings.

Step 3: Prototyping

Picture of Prototyping
Prototyping

Solder the parts according to the schematic. Be sure the switch is off. Spin the rotor shaft with your thumb and index finger. Be patient. It takes about a minute to charge the super capacitor. Switch on and check how long it works.
Fearce17 months ago

I've made one of these yrs ago. Still use it to this date.

One of the DC brushless motors I used was from an OLD record player and easily puts out a voltage spike of more than 9v.

This is a great reference video (minus the DC motor as a power source):

https://www.youtube.com/watch?v=ic_yEUV7Y3c

wgsinc2 years ago
"Look ma, No Batteries"... This is my kind of Instructable. Simple with few components.
Make a few of these -and you may be all set for the Myan cataclysm of Dec 21, 2012, if there is a major black-out .
"Supercapacitors" are the batteries of the near future.
(Good work, kostya - but the circuit you drew is not quite correct.
The diode is "blocking" the current from the motor.
Suggest you draw the diode 'ACROSS" the motor with reverse polarity to the motor.
That will protect it and allow the Supercap to be charged also.



kostya (author)  wgsinc2 years ago
Supercapacitors are still pricey here. Thanks for your suggestion.
Check the direction of the diode!!!
kostya (author)  thangtran10242 years ago
I've just opened up the flashlight and checked. You are right. The Schottky is soldered with the cathode to the motor. Thank you!
kostya (author)  thangtran10242 years ago
I've just opened up the flashlight and checked. You are right. The Schottky is soldered with the cathode to the motor. Thank you!
kostya (author)  thangtran10242 years ago
I've just opened up the flashlight and checked. You are right. The Schottky is soldered with the cathode to the motor. Thank you!
this project is awesome! great idea for emergencies
kostya (author)  amandaghassaei2 years ago
Thank you! Vote, please!
A Really neat idea! Thanks for sharing!

An interesting modification would be to have the motor output go to a bridge rectifier (the AC input terminals) so that it can charge the supercap regardless of the direction it is spinning.

One concern: What if you spin your motor fast enough to generate over 5.5V? I think your super cap may not last long. ;-)
kostya (author)  wannabemadsci2 years ago
Thanks! I have got an idea to build another flashlight with AC input, but there will be no DC motor at all. Your can rectify AC voltage with a simple circuitry and charge a super capacitor. As for your concern, I am in a great doubt that somebody is able to spin the motor so fast to overrate 5V. I checked with the multimeter and it showed 3V at most.