Replacing Old Flashlight Bulb With LED

by chienline in Circuits > LEDs

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Replacing Old Flashlight Bulb With LED

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It was my boy finding this classic flashlight and asking me to make it works. Replacing the batteries with new ones didn't make it work. Then I took it apart, saw that the bulb's flashing wire had broken. Searching all around (my house) I couldn't find a replacement bulb. Seeing two AA batteries (3V) made me think of replacing it with a white LED. Why not? I have plenty of them around ^_^

Parts and Tools

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Parts :

  • A classic 2 x AA battery flashlight.
  • A white LED.
  • 2 cm of small cable [18-22 AWG will do]. We need its jacket only.

Tools :

  • Wire cutter.
  • Solder.
  • A small head screwdriver.
  • Hot glue [optional].
  • File [optional].

Get the Bulb Base

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Take off the bulb from its base. It is small and fragile. You just need to move it left-right-left-right until it get loosen, then pull it out. Clean the whole base using a small screwdriver.

Prepare the LED

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Bend the cathode (-) of your LED forming 90 degrees from the anode (+) of the LED. Well, for instant, the larger piece inside the LED is cathode and the smaller piece inside is anode. So far I keep remembering LED anode-cathode in this way, because I was once wrong when using longer-shorter pins due to factory's fault. For more confirm, please connect the led directly to 3 Volts battery, it won't light up if you put it the wrong way. Then bend the pin connected to the negative (-) of battery just like the photo above.


Get a small piece of wire, we need its jacket only, any wire whose jacket fit the LED pin. Pull out the wire strands, then put the LED anode (+) pin in it. This is to avoid shorting to the negative base.


Now bend the cathode (-) pin down to the former bulb negative solder pad then smoke it... I mean solder it there :)


We are almost done :)

Finishing

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I use clear tape to seal the border of the anode (+) pin to avoid short. Actually I intended to fill it up with hot glue to make the LED steady on its new container but at that time I couldn't find one, while the deadline given by my son was expiring that day :D

So.. I lighted it up anyway.



If you have a file handy, clean up the bulb negative contact which will be touched by the sliding switch connecting it to the negative of battery.


A happy Son, a happy Father, and an old stock brand new Flashlight ^_^