Emergency Spin-it LED Flashlight





Introduction: Emergency Spin-it LED Flashlight


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

Step 1: 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).


Wire cutters
Soldering iron
Drill and drill bits (optional)

Step 2: 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


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.

Step 4: Making the Enclosure

Making the enclosure

Remove the label and grease from the plastic bottle. Make a hole in the bottom. I used a hot electric wire and a file to do the job, but you may drill. The diameter should be equal to the diameter of your DC motor’s body. Make a hole right in the center of the bottle cap (5mm in diameter to insert the LED). I used a hot nail to do it. Make 3 tiny holes on the bottle neck to install the switch. I used a small hot nail to prick holes. The enclosure is ready.

Step 5: Assembly


Insert the motor and the LED into appropriate holes. Install the switch on the bottle neck. Solder the parts according to the schematic. You are done.

Step 6: How to Charge With a String Loop

How to charge with a string loop

If you don’t want to be bothered with finger spinning, you may try to charge with a string loop. Take a length of strong string (about 2m.) I think a dental floss will work ideally in this case, but I used what I had at hand. Make a loop and wrap it around the pulley on the rotor shaft. Place the flashlight on flat surface and press it with your foot. Tighten the loop and insert a stick (a pen or a pencil) into the other end. Pull hard downwards on one branch of the loop. Make a dozen of pulls and your flashlight is charged. By the way, string is a must in any survival kit.



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    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):


    "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.

    1 reply

    Supercapacitors are still pricey here. Thanks for your suggestion.

    I've just opened up the flashlight and checked. You are right. The Schottky is soldered with the cathode to the motor. Thank you!

    I've just opened up the flashlight and checked. You are right. The Schottky is soldered with the cathode to the motor. Thank you!

    I've just opened up the flashlight and checked. You are right. The Schottky is soldered with the cathode to the motor. Thank you!

    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. ;-)

    1 reply

    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.