Super Capacitor Flashlight 2.0





Introduction: Super Capacitor Flashlight 2.0

About: My name is Zach Sousa and I'm a Canadian highschool student that has a passion for making.

In this instructable I will show you how to make a super capacitor powered flashlight.
This means that you can make a flashlight that can charge in seconds and last for around 15 minutes depending on your capacitor.

Note: I just finished calibrating my scratch built RAMPS controlled printrbot simple so I will make a lot of 3d printed instructables now Just suggest any ideas for new projects!

Step 1: Parts and Tools

These are the parts and tools you will need to make this project:
1 farad 5 volt super capacitor
5 mm led
Momentary switch
3d printer
USB male cable ( stripped)
Soldering iron and solder

50 ohm resistor(The capacitor max voltage is 5 volts so we want to lower the input voltage)

Step 2: 3d Print Case

Here are the stl files to print this:

Step 3: Make Circuit

Solder some wire to the negative lead of the super capacitor to the negative lead on the led and wire the positive end of the super capacitor to a momentary switch. Wire the other side of the momentary switch to the positive side of the led. Now solder the positive end of the USB male plug with a 50 ohm resistor going to the positive end of the super capacitor and the negative wire from the USB male jack to the negative lead on the super capacitor.

Step 4: Fit in Enclosure

Put all of the parts in the enclosure you may need to file down the rectangular hole for the USB plug.

Step 5: Finished!

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Comment about other ideas for some more projects!



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    11 Discussions


    4 years ago


    Thx. I've been looking for cheap parts sources. Went old school on a few projects. Pulled apart several old tvs. Got a monster cap bank. But, it's huge in size.

    Yes efahrenholz the printer's design is not very good: y axis sag is terrible on this printer so I have to level the print bed in a specific way in order to have it level. I recently added gt2 to the printer and it is keep jamming. Y axis uses fishing line so the y axis slips a lot.

    I think that the reason that my capacitor lasts longer is because it is a double layer capacitor where as most of the other kinds of capacitors are single layer I don't really think that you would need a 1 farad but it does have to be double layer.

    you might consider recalibrating that printer again.

    So what makes the higher capacitance capacitor last for longer time? I have 450 v 220 uF capacitor that gives a strong spark and discharges in milliseconds..

    1 reply

    The energy stored in a capacitor is calculated as:

    U² (voltage) x C (capacitance) / 2 = E (energy)

    If fully chared the capacitor from this instructable could store 5.5² x 1 / 2 = 15.125J.

    Your capacitor however can store 450² x 0.00022 / 2 = 22.275J which is even a bit more. However your capacitor needs to be charged at that voltage if you want to store the maximum energy. It's not only rather complex to generate such high voltages (compared to an available 5V supply) but can also be highly dangerous.

    However those low voltage capacitors can also generate quite large sparks. I have a 2.7V 10F type lying around which does exactly the same. To generate a large spark the capacitor needs to be able to

    1. discharge "a lot" of energy

    2. in a short time

    The only limit is the capacitors internal resistance called ESR (equvilant series resistance) which is specified its datasheet. There is a realy interesting (an entertaining) video on youtube called "Fun with ultracapacitors!!" illustating the enormous current possible.

    An important thing to note is that according to the official USB specifications the voltage can be as high as 5.25V which can damage any 5V rated capacitor. That means you should pick one which is rated at 5.5V (common value) or add a simple diode in series (1N4001 or simliar). The diode will cause a voltage drop of at least 0.3V (the drop is larger at higher currents) and thus protect the capacitor.

    With this circuit the LED will be dim after a short time because the voltage (at the capacitor) drops rather fast. A better approach than the current limiting resistor in series with the LED would be a constant current source. A constant current source can be rather simple and build with only 2 transistors and 2 resistors. Ideal would be a little step-down converter or even better a step-up and -down converter, however this might be a bit overpowered for a simple flashlight like this.


    4 years ago

    I would add a loading resistor, because at the first miliseconds the currend is as high as if there was a shortcut.