How to Make a LED Flashlight

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Introduction: How to Make a LED Flashlight

HI! I am Junez Riyaz, currently doing Bachelor of Technology in the field of Electronics and Comm...

A flashlight ("torch" outside North America) is a portable hand-held electric light. Usually, the source of the light is an incandescent light bulb or light-emitting diode (LED).

Now I am going to instruct how to make a LED flashlight with less number of components.

Get Started..

Step 1: Components Required

10 W SMD LED -1 ( ebay or amazon)

9V Battery -1

9V Battery Snap -1

Switch -1

Double sided tape

Step 2: Placing Components

Apply a piece of double sided tape at side of the battery and top of the snap.

Place switch on the double sided tape which was on side of the battery.

Place SMD LED on the double sided tape which was on snap.

Step 3: Circuiting

Solder negative terminal of the snap to negative terminal of led.

Solder positive terminal of the snap to top pin (pin 1) of switch.

Solder a wire from middle pin (pin 2 ) of switch to positive terminal of the LED.

Here the construction of flashlight is completed.

Note : I recommend you to use 9v rechargeable battery because normal battery discharges very fast or you can use any 12V rechargeable battery source.When you are using 12V source ,there is a need to add a heat sink to the LED.

Step 4: Construction and Test Video

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Feel free to comment.

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26 Discussions

A 12V, 10W LED means it needs ~833mA. A 9V battery is usually only used for ~ 100mA or less and at this discharge rate is rated at about 310mAH or it would last about 3 hours. See:

http://www.powerstream.com/9V-Alkaline-tests.htm


Now, at a 1A discharge, or power of 9W, close enough to run the 10W 12V LED. The above tests show a good alkaline 9V battery lasting about 0.09 hrs (90mAH/1000mA = 0.09 H) or about 5.4 minutes. The best would last 0.3 hrs (300mAH) or about 18 minutes.

However, this is running the battery down to 0.1 Volts and most 9V applications run the battery down to about 5 or 6 Volts and a 12 V LED would probably turn off at about 6 Volts (this is just a guess I'd have to test one to be sure) and so in all probability the flashlight would last perhaps only seconds before running out of enough power to run the LED.

Now, if you limit yourself to a 3V ultrabright white LED you can use "dead" 9V batteries ~ 4V without a resistor and get hours of use out of it. Been there, done that. If the 9V battery is at about 6V I use two 3V LEDs in series until it gets down to about 4V when I can use the same battery with one 3V LED.

So how long does your 10W, 12V LED last on a small 9V battery?

3 replies

Sounds good! I use "dead" 9V batteries for LED flashlights using a resistor and a 3V ultrabright LED which works really well & brings the 9V battery below 3V. What is the voltage of your 9V battery after it is "dead" for this use? Is it high enough 4 - 6V to use it again with a 3V LED?

I had LEDs that needed 9v, this way I did not add a resistor. It seems to last quite some time.

thats must be have resistor too, because you burn led if not resistro and 9 volt little battery not can use than only few minit. and have empty. not good idea, but if you use 5W resistor, about 10 ohm, 3 pcs 10W led and good li-ion battery and arduino tiny you can made good flash light and save energy more. arduino can code only blink, only fulltime open, or different blinking time what need, or stobe light. easy. and save battery more :)

3 replies

Matt, lol... The way you phrased your wording ?! Hilarious! It actually sounds exactly like the examples of speech my other half contorts!

The LED is I used will not damage at 9v , because its maximum operating voltage is 12V.

Thanks for your suggestion

hi.

You can also get a free Free 9V Battery Connector if you got a dead/depleted 9v battery lying around.

https://www.instructables.com/id/DIY-9-volt-battery-connector-for-free/

1 reply

Very nice Mr.Riyaz. Keep it up.

1 reply

White leds are current mode devices, so to drive it properly you need a constant current source not a constant voltage source. Ideally you want a current mode boost converter otherwise you won't get the best out of the led. Laser diodes are also current mode devices ;) An LM317 can be used as a very basic current source but won't boost the voltage only drop it. All these 10w less are slightly different so some will draw 10v whilst others 12v. Hope that helps clear things up for those that don't know.

1 reply

10w and 9V = this formula

10watts defided tru 9V = your current-1.1Amp

so the battery is verry soon emty.

lets say you got an 1100mAh battery then it wil last 1 hour

so verry suffisiant its not but a simple fast led lighter. and yes at 9V it wil not get very hot. but a little piece of 1mm thik aluminium between it ,wil be better

and to make it a REAL POWER LED, put a little booster between it. then you got a verry bright led. but you must boost up to 16V with these kind of leds. for maximum power