How to Make an LED Glow Using Maximum 47 Miliwatts Input?

A red LED requires about 1.7 volts. 47 milliwatts/1.7 volts is about 30 milliamps, definitely enough current to light an LED. If your solar array doesn't have sufficient voltage, you'll need a circuit like a Joule Thief to reach the LED forward voltage.

There are a lot of solar-powered toys around. Some have a magnetic pendulum that swings over a coil to periodically turn on a transistor. This takes just a minute amount of power and will work with ambient light.

https://www.thesolaradvantage.net/best-solar-toys/

These are really cool, I have them along the house as well as the single lights...I have taken some apart for repair, they are probably as good as it gets...

https://www.amazon.com/BRIGHT-Color-Changing-Lights-Outdoor/dp/B01MRSVGVT/ref=sr_1_24?qid=1564585464&refinements=p_n_feature_eighteen_browse-bin%3A5699955011&s=lamps-light&sr=1-24

These lights have a solar panel about 1" square that charges a AAA battery, and put out about 3-4 watts...unless you can store energy, you need enough juice to light the LED, which will require a larger panel than you have there....Typically, the forward voltage of an LED is between 1.8 and 3.3 volts. ...You typically need between 10 and 26 mA for the LED circuit...

http://www.theledlight.com/led101.html

thx for the prompt answer guys, the pendulum will not work , I already try it , the joule thief also don.t work, to achive the best performance I need to create a "piston" with magnet on it which will action on the coil ..... I am looking forward for a constant glow and I don.t wish to use batteries.

I ' ve tried first to create a generator using rotation like in the presented movie, eliminating the friction much as possible, but I wasn,t satisfied. Why to rotate the magnet ? when I can use the gravity and the voltage variator to obtain that dc power and make the led glow constant.

So , if I understand you, and I don't think I do, you are now contemplating some mechanical input to generate some additional voltage? ...rather than just using a bit larger solar panel, that costs about $1...What exactly are you trying to accomplish here?

Why don't you just buy a little hobby generator for a few bucks?

Here is another test, which not satisfied me.....

You just seem to be playing....if you want to build something you have to make a feasible plan....experimenting like this might be fun for you in some way but it has little chance of success....If you're goal is keep the red LED lit, there are several ways to accomplish that, you don't seem to be interested in any of them....Is this some misguided quest for "free energy" perhaps?

• nothing is free ! this is for sure, there is no free lunch. I am not looking for free energy. I don.t wish to buy an educational generator, I am building small generators layouts electric motors and electric scooters (which are not for sale .) lets say a strange hobby.
• if I will use a large solar panel , the led will work without problems of course, directly conected to the panel, but where is the challange ?
• What do I wish to achive ? to obtain 99. 99(9) percentage of the input power....I know imposible.

So you want to improve the efficiency of what exactly? The solar panel? The LED light? I haven't seen any innovation here, no new concepts, nothing really...Your time might be better spent taking some classes in these areas of interest...

there is no inovation it is a challenge: how to light a led using a vimun 3012 - 2a mini solar panel with maximum 47 miliwatts available, if you will succed with a transformer, Joule Thief, step up booster, etc , I will be more than happy to show me how to do this to avoid all the mechanical problems....... As we all know energy input = energy output minus loses. I am triyng to have minimal loses. I wish to mention that youre led should light constant. I AM LOOKING TO REDUCE FRICTION MAGNET COIL to have minimal loses. Ps all my projects are prototypes (this mean inovation)

Why not just scavenge a solar powered set of Xmas lights and use the setup to drive a led and if you don't like a battery why not a super condenser? Just adjust the series resistor to the led to give 10mA and that should be bright enough.

Of course you could get technical and drive the led with a chopper circuit thereby you can vary the duty cycle to conserve more storage energy. A solar panel from a single AA battery powered light will generate about 1.8V at the solar panel from interior lighting and more if it is placed against a window.

I am looking in the direction of energy harvesting , to use each miliwatt available (try to easte nothing I know it is hard this is the challenge...) and I think I am on the suitable forum......

It will be posible to light a led in another way using less then 47 miliwatts ? this is the question ? If the answer is yes , I am waiting to tell me how.

thx

High Efficiency LED's

There are high efficiency LED's which can light up with as little as 2ma of current. There are different voltage requirements down to 1.75v. If you had one which lit well with 2v and about 2ma then the power requirement would be something like 4milliwatts, far less than your available 47mw. You could run something like ten of these off of your solar panel at max output. Just do a web search for 2ma LED to find these high efficiency LED's. Most will be surface mount. One hit I found with quite a few alternative devices is here. You may need to scroll right to see the forward volage ratings and the forward current ratings in their table. LED's vary in the forward voltage requirement so you could sort them by gradually increasing the voltage available to achieve a kind of digital meter of the voltage output of your solar panel. Your bar meter would be using as much energy as the panel was producing at a reasonably high efficiency. You may need some means of limiting the current through already lit LED's depending on their characteristics. A gold foil supercapacitor might be used to buffer the power output of the panel to reduce oscillation frequency of the last LED to light at any specific voltage if you wanted to do that.

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thewildotter

thx, it is a good ideea to fimd a led with the indicated characteristics

https://www.instructables.com/id/DC-Generator-Powered-With-a-Single-Mini-Solar-Pane/

..."single mini solar panel vimun sc-3012-2a 29.44mm×11.6mm×1.1mm, which can make a led glow which provide only 1,25 V X 0.054 ma"...

...as has been said, you don't have enough juice...you are misquoting the available wattage....

Yes, it is me on the instrucrables, I always share, and I aspect people to do the same, I don't get it ? It is just a challenge. This is my office with spinning and moving things. So you are saying that it is imposible to make that led glow more than that ?

https://www.led-professional.com/technology/light-generation/successful-extraction-of-light-from-semiconductors-with-the-highest-efficiency

I calculate the area of your solar panel is 0.00036 square meters. Sunlight has about 1000 W per square meter and a solar panel is probably 15 percent efficient at best. So in high noon sunlight your available power is 150 x 0.00036 W, about 54 mW. So your quoted 47 mW (39 mA) is probably about right for the maximum output in high-noon sunshine. I would assume your office light is nowhere near that bright.

"Indoor Light Levels

The outdoor light level is approximately 10000 lux on a clear day. In a building in the area closest to the windows the light level may be reduced to approximately 1000 lux. In the middle area it may be as low as 25 - 50 lux. Additional lighting is often necessary to compensate low levels."

https://www.engineeringtoolbox.com/light-level-rooms-d_708.html

The voltage of your panel will be 1.2v no matter how bright the light. Voltage is relatively constant but current increases with illumination. An LED has the same kind of characteristics, there about a constant threshold voltage before current will flow and light produced. (The value of this voltage is dependent on color.)

(Single cell - your panel is 2 in series)

http://solarbotics.net/starting/200202_solar_cells/200202_solar_cell_use.html

http://lednique.com/current-voltage-relationships/iv-curves/

Unfortunately, LED voltage is higher than solar panel voltage. To light an LED with a solar panel requires either putting two panels like yours in series or using some kind of voltage multiplier circuit.

The choice of multipliers is limited at low voltage (1.2v). The Joule Thief is the most popular multiplier circuit that works with low voltage.

https://en.wikipedia.org/wiki/Joule_thief

Light intensity inside an office is typically 1/10 of outdoor sunshine.

If 47 mW is your outdoor power (39 mA), a doubler circuit will at least cut this in half. Indoors, you can expect 1/10 of this, < 2 mA after the doubler. This is probably insufficient to produce much LED light.

Bottom line: You can probably make it work outside in the sunshine (with a dark place to view the LED). Indoors, there is probably not enough light.

This is what I am considering it a profesional answer. Thx Rixter !

I won't say it's impossible because you could have a storage device that would store the energy produced by the solar panel, and have a short duty cycle....this is how solar garden lights work, they store the energy produced during the day to light up for a few hours at night...I would think that the possibility of that small inefficient solar panel lighting an LED in less than optimal light, is not probable...cobbling gizmos together is likely to produce nothing but frustration...