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In India There are many villages where there is no light , children can't study at nights.and this is not just in India,
Every developing country have the same issues.There are many available products for solving the problem ,but the light output vs price is not that economical for a poor man. In India it would be much better to buy under 100 but i decided to do it under 1$ 60.

Features of this lamp:

  • Lithium ion Powered
  • Rechargeable
  • Long lasting -once charge can last more than 4 hours(tested max and still running on that charge)
  • Outputs like a 20w ccfl

For making this lamp you will need

  1. Lithium ion battery (i used camera battery)i bought at 40 INR
  2. SMD led i bought 10 for 20 INR
  3. Switch for 1 INR
  4. and a case for 5 INR

Total 66INR equals to 1.00 $

Step 1: Preparing the LEDs

SMD led don't have led so they can't be attached to pref board .but i like to differ in it instead of using legs i rather solder to led directly on the perf board in this , In this way we actually made and array of led , this led are made such that all the 10 are connected in parallel but in 5 each row.

Why using 5 in each row ?

Simply because i wanted the light to be compact and the source to be strong ,if you won't you can use other arrangement . you can tell me how you would do.

What are the led

I actually i don't know what are the leds i brought them from a local shop .they were cheap :)

Step 2: Connecting the Battery and Switch

Choosing the battery

I wanted to use lithium ion as they are light can be easily used in portable projects.

I could have used the 18650 battery but those were too big so i changed it to camera battery, as they were fitting perfectly inside the box i had chosen.

they are smaller than the bl-5c and also they are 1600 mah

decent power for a light

Choosing the switch

I firstly use a small mini switch but later my mind shifted to this switch it looks better and since its only about on and off,
SPDT are great for the work

The connection is given in the figure

  • connect positive to switch end
  • connect other switch end to led anode
  • connect led cathode to battery ground
  • take two more wires and connect that with ground and positive of the battery,this will be connected to rechargeable block(In my case it connects which is two female header ) that connects to a external rechargeable module.

Step 3: Preparing the Case

Any Electronic circuit are incomplete without a chassis ,or enclosure.
I need to put everything inside a enclosure so i used this tiny box for the purpose .i need some drilling specially for the switch . also for the header for the recharge module .

I used a Dremel drill bit and then a sand bit to make the hole in the figure.

Then it was time for putting everything inside the box .

I used a glue gun to put everything in its place firmly also to insulate everything.

Step 4: Painting the Case


I used a transparent case will make light come out from ever corner so it needs to be painted .

I had a matte black paint spray so i decided to use it for painting, but i need to make sure the upper side from which Light will come out be transparent.
So i need to mask it .
I did not had any masking tape so used simple black tape for the work.i used an xacto knife to cut the side of the tape to match the surface of the box.

Then i used my spray paint to paint the box.

Spraying using a spray can

  1. Shake the can well
  2. Spray on the object and keep the spray constant
  3. apply the paint on every surface
  4. Give atleast 30 min to dry depending on temperature of sorrunding
  5. Repeat the step for 3 times
  6. you will end with a sexy matte finished surface(i also painted the switch black)


Step 5: Peeling Off the Mask and Using It

After the paint has dried its time to peel the mask off

CAREFUL

The mask can also pull some paint from the surrounding as the paint is a continuous layer.you need to use the knife to make sure the the masks does n't take the paint of.
i made the mistake , but thanks it could be reverse .
Peel Slowly and gently and nothing shall go wrong but if it goes , use a brush and apply paint where the paint goes out

So last we end with the 1 $ pocket emergency light

i have been using this last week it helps me a lot i just had to charge once and still it is working fine :)

Don't forget to follow me for upcoming projects
and like my facebook page Makewithrex

<p>You can avoid the use of the TP4056 module if you are using a CellPhone Battery, this already come with a little module similar to TP4056, if you disassemble a CellPhone Battery, you will get the horizontal circuit that make the same functions that the TP4056, BUT if you Litium Battery don't have that module already installed, you will need an TP4056 module, please check this tutorial to understand my point.</p><p><a href="https://www.instructables.com/id/DIY-carbon-heated-beanie/" rel="nofollow">https://www.instructables.com/id/DIY-carbon-heated-...</a></p><p>Anyway it's a good idea and if you can recycle all the components from another source, you can make this project more cheap.</p><p>Good Luck. </p>
<p>Batteries usualy have 3 contacts (modern can have 4 or 5) but you can find &quot;-&quot; and &quot;+&quot; mark on your battery.</p><p>My<br>battery has overcharge ic board inside so I can connect it directly to <br>any USB. If you will use unknoun 3.7v battery you should use a charge <br>board like this one:</p><p><a href="http://www.ebay.com/itm/Li-ion-Lithium-Battery-Board-Charger-Module-Li-Board-5V-1A-Mini-USB-Board-/321753747722?hash=item4aea04910a" rel="nofollow">http://www.ebay.com/itm/Li-ion-Lithium-Battery-Boa...</a></p><p><a href="https://cdn.instructables.com/FQ8/5E3V/IFPMG780/FQ85E3VIFPMG780.LARGE.jpg" rel="nofollow"> </a><a href="https://cdn.instructables.com/FO4/PPCC/IFPMG784/FO4PPCCIFPMG784.LARGE.jpg" rel="nofollow"></a></p>
<p>Thanks a lot for the suggestion the question is in my case the battery has two - one plus , so can i charge it directly with 5v usb ?</p><p>will it be safe ?</p>
<p>I suggest that you first learn the configuration of the model of your current battery and if it count with a inner regulator, will be safe to connect directly to any USB 1W, but if you are not sure that you have that regulator, it's better to use a external one. </p>
<p>I suggest that you first learn the configuration of the model of your current battery and if it count with a inner regulator, will be safe to connect directly to any USB 1W, but if you are not sure that you have that regulator, it's better to use a external one. </p>
<p>I suggest that you first learn the configuration of the model of your current battery and if it count with a inner regulator, will be safe to connect directly to any USB 1W, but if you are not sure that you have that regulator, it's better to use a external one. </p>
<p>And also, you can recharge your flash directly connecting it to any 5V USB source easy and fast.</p>
<p>10 LED's in parallel would divide the current 10 ways. I found some similar looking SMD LED's with the ratings pictured below. 300 ma each X 10 = 3,000 mah so it would last 1/2 hour on a 1600 mah battery. Also the LED is only rated to 3.3 volts</p>
<p>Also they cost .53 each too.</p>
<p>My one 0.03 $ each</p>
<p>Sorry but this led are 5630 my ones are 5025 with 50 ma each that equals 500ma theoretically so i should get 3 hours but the it is lasting more than 4 hours but lumes drecrease </p>
good ...but these components are expensive in here <br>that switch is 10 inr<br>battery 150inr<br>.<br>.<br>
<p>where do you live bro, i brought all the things from local market also i buy alot so i get cheap</p>
<p>40 Rs for 1600 mAh battery????</p><p>how 10 LEDs work on 3.7 v battery????</p><h3><p>i can't believe it</p></h3>
<p>Hi</p><p>You are worried that 10 LEDs should need 10 x (3 to 5V). Worry not - these LEDs are in parallel so only need 3V to 5V.</p><p>What you should be worrying about is the lack of any kind of proper current limiting - this innocent may have got away with it - the current will be set by whatever resistance is in the battery/wiring and whatever volts these LEDs happen to operate at. This is a BAD circuit.</p>
<p>Just add LM 317 in TO92 transistor package as current limiter and you should be OK.</p>
With a regulator You Will have too much drop voltage, in order to limit current try to put a lillte resistance or a filament lamp in series.series.
<p>TI datasheet says the min. recommended volts drop is 3V, and it doesn't come in T092. Apart from that...</p>
<p>I myself have in the transistor package. Of course I got these from Singapore. The 3 volt recommended drop is for using it as a voltage regulator and in TO-220 or TO 3 package not for current limiter configuration. There is also another voltage regulator from Panasonic in TO 92 package which can go down to 1.2 V. You will have to search for it. </p>
<p>That would double his price! LOL.</p><p>But seriously, as others have pointed out, LEDs don't tend to share well with others. Just setting up a fixed current of ten times one LED and feeding it to ten in parallel could quickly lead to a really neat cascading failure.</p><p>It goes like this. One LED is selfish and pulls a little more than his share. He starts to overheat and this makes him draw more (an unfortunate side of LEDs). This makes him overheat more... And then he dies in a bright flash.</p><p>Now there are only nine LEDs left to consume your current. One may be a hog...</p><p>As this cycle repeats, you can see how it speeds up.</p><p>Pretty soon you're down to two LEDs getting that ten LEDs worth of current, then one, then none.</p><p>Blink.........blink.........blink......blink.....blink....blink...blink...blink..blink.blink</p>
<p>Then there is an alternative way to play it safer. The LM 317 in TO92 <br>plastic transistor packages are pretty cheap here in India. Directly <br>converting to $ terms would be like $ 0.05 &cent; each. Use one in series <br>with each LED. Cost may double but the components would be a whole lot <br>safer. If one were to use a trimmer, costing around $ 0.01 &cent; each one <br>can really fine tune the whole thing for even brightness. Again Philips 1/2 watt metal film fixed resistors cost like 1/2 &cent; each.</p><p>BTW if you check on the eBay product site there is a very clear warning that these devices need heat sinks to operate. </p>
<p>Then there is an alternative way to play it safer. The LM 317 in TO92 <br>plastic transistor packages are pretty cheap here in India. Directly <br>converting to $ terms would be like $ 0.05 &cent; each. Use one in series <br>with each LED. Cost may double but the components would be a whole lot <br>safer. If one were to use a trimmer, costing around $ 0.01 &cent; each one <br>can really fine tune the whole thing for even brightness. Again Philips 1/2 watt metal film fixed resistors cost like 1/2 &cent; each.</p><p>BTW if you check on the eBay product site there is a very clear warning that these devices need heat sinks to operate. </p>
<p>Hi</p><p>You are worried that 10 LEDs should need 10 x (3 to 5V). Worry not - these LEDs are in parallel so only need 3V to 5V.</p><p>What you should be worrying about is the lack of any kind of proper current limiting - this innocent may have got away with it - the current will be set by whatever resistance is in the battery/wiring and whatever vots these LEDs happen to operate at. This is a BAD circuit.</p>
<p>seriously bro here this is so cheap ,i bought couples of them </p>
<p>hello friend (<br>͡&deg; ͜ʖ ͡&deg;)</p><p>in Kerala you need minimum 150 Rs for this items</p>
<p>I can send you the battery from here if you want </p>
<p>'Why so serious man?&quot; :)</p><p>where is your place buddy?</p>
<p>West Bengal</p>
<p>seriously bro here this is so cheap ,i bought couples of them </p>
<p>Led looks like SMD 5025. The voltage is 2.0 and max current is 50 ma. To be safe it needs a voltage drop of 1.7(3.7-2.0) So it will need a .085 ohm resistance. Ideally LEDs should have individual resisters because the characteristics of LEDs vary Even if 10 are used it needs .85 ohm. (1 Ohm 1 W)Probably the wires + the internal resistance of the battery may account more than that. That is why LEDs didn't burn out. If dry cells are used there should be no problem because they have much larger internal resistance compared to Lithium battery. Is the battery going to be recharged in a cell phone?</p><p>A solar battery from China is very cheap. That will make it a forever light especially in tropics. These days nobody has to buy Lithium batteries with so many discarded cell phones. If cost is not a factor using super capacitors and solar instead of lithium battery will make it a forever light.</p>
<p>Thanks for telling the package size</p>
<p>You are right about using a dropper resistor to limit the current and to<br> use one on each led. However, I'm not sure where the 0.085 ohms came <br>from (see later), but it's way too small. To calculate the dropper resistance use Ohm's Law (V=IxR hence R=V/I where V is in volts and I is in amps, not mA) using the required current and voltage drop. This works out as:</p><p>R=1.7/0.05=34 ohms for maximum current. Therefore in order to limit the current to a less than maximum working current and to increase battery life, the resistance should be increased proportionately, maybe to 47 ohms (36mA) or even 82 ohms (20mA).</p><p>Or just use a dropper resistor calculator;</p><p>e.g. </p><p><a href="http://ledcalc.com/" rel="nofollow">http://ledcalc.com/</a></p><p>So the minimum resistor value should be 34 ohms per led. The wattage isn't too important as the energy dissipated in the resistor (VxI) is only 0.085W (85mW) maximum. (In doing this I now realise where you made the resistor calculation mistake, you multiplied the voltage by I instead of dividing it to calculate the resistance).</p><p>Although supercaps might seem to be a possible replacement for a lithium battery, it doesn't turn out so simple. There are a few problems using a supercap. Firstly, the voltage on a capacitor decays linearly with the current taken, unlike a battery which holds it's voltage pretty steady then decays quicker at the end. This means you need to use a voltage stabilising circuit. Secondly, the actual capacity of a supercap isn't as high as a battery for the same volume. Assuming geekrex's design of 10 leds is running for 4 hours at 20mA per led, this means it is using 2vx0.2A for 4hrs (assuming no losses in dropper resistors etc). To work out how large a capacitor would need to be, you need to use the following equation:</p><p>C=VxQ where Q is charge and Q=It (I in amps, t in secs).</p><p>So, the capacitance needed is C=VxIxt=2x0.2x4x60x60=5760 Farads.</p><p>There are many designs on here for supercap lights but they tend to be for low light/current and don't last very long but work well as quick charge emergency torches. e.g.</p><p><a href="https://www.instructables.com/id/Micro-usb-30F-Supercapacitor-Flashlight/" rel="nofollow">https://www.instructables.com/id/Micro-usb-30F-Supe...</a> </p><p>which lasts for about 15 minutes using a 30F supercap. They are useful because the advantage of the supercap over the battery is that it can be recharged much quicker and it can also have a longer shelf life holding a charge.</p>
<p>Don't forget that the &quot;3.7V&quot; battery will actually be more like 4.2V when it's freshly charged. You should be using that value when you consider the maximum curren, voltage drop calculations for the dropping resistors.</p>
<p>Also super caps are expensive here :(</p>
<p>Your math is incorrect. The correct answer is R=V/I=(3.7V-2.0V)/0.05A=34 ohms for each LED, and if using a common resistor for all ten LEDs it would be 3.4 ohms.</p><p>LEDs don't share current very well when put in parallel, unless all of their forward voltages are exactly the same. This might be the case if they came off the same die, but otherwise it is not. So, the LED with the lowest forward voltage, would take the most current.</p>
Thanks, mikeanton. You are right. I multiplied E with C instead of dividing. I should have used the resistor calculator. Things get rusty with age.
<p>Leds where of same lot </p>
Thanks mikes ton for the correction. I am sorry I messed up the calculation.
Thanks Wobbler for the correction. You are right. I messed up the calculation.
<p>No problem. Everyone does at some time or another!</p>
<p>Thanks for telling me the package size i was totally confused with it, and the battery is going to be recharged in custom charger made from tp4056 .if i used a solar cell i will still need a battery to store the charge yes the charge can be stored in the super cap will try to make a solar version next time</p>
<p>Excellent DIY! Thank you! I don't know that I'll do this specific project; however, you gave me some super ideas and I learned something!</p>
<p>Thank you</p>
OK, got it.<br>I thought it was for that TP4056 module.
<p>The cost of battery is not 100 its just 40</p>
Nice and simple!<br>Here in chennai the battery is costliy, can u pls ship them for me?<br>What abt TP4056? Its cost pls.
<p>it cost 100 rupees max with delivery charges on ebay.in buy one and turn that into a charge kit</p>
ok, i found the TP4056 in ebay.<br>Now, i need the battery, can you pls send it to me, let me know the cost + shipping charge to Chennai address.
<p>I already said the cost of the battery and shipping will be 100 rupees max i guess</p>
<p>What part of India are you in? And what is the source of your components? I have very easy access to Lamington Road electronics market in Mumbai. What would be the cost for shipping the LEDs to say Vadodara (Baroda) Gujarat or Mumbai? </p><p>Would certainly appreciate your feedback.</p>

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