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Versatile compact 9v LED lamp

by Chris J. @ 12:37. Filed under Projects

It’s the same thing every time, no lamp in place when you need one - so why not build a lot of these - always in place !

 

You need:

* 1 fresh 9 Volt battery
* 1 old (empty) 9 volt battery
* 3 high intensity LED’s (white, 25.000 mcd - 3,8 volt and 20 mA - 35 degrees)
* 1 magnet (memory magnet for fridge)

Start with localising the anode (+) and cathode (-) of the LED. Mark them up as I did (with a felt-pen), red for anode (the longer leg) and black for cathode (shorter leg and phased edge on the bottom of the plastic of the LED). I will in the following text write red and black.

Then you need to open the old battery, as we will use the plastic part with contacts on the top. Don’t forget to throw the rest in recycling for batteries.

 

Now to the LED’s. Carefully bend the legs towards each other, hold between the plastic and bending point with a prier as you see in the picture.

 

Solder the legs together, with red to black in all three LED’s, put them as tight as you can and solder quickly,
as LED’s don’t like high temperature. Beware of short circuits between the legs.
Then cut off the rest of the legs outside of the soldering points. Check that you have one black side and one red side of the LED’s with the legs intact.

Place the LED-packet in the plastic top, trim and adjust the black and red legs so they fit to the back of the contacts. The red connects to the contact which have openings, and the black to the round contact (opposite to the fresh battery) and solder carefully and quickly (the LED’s don’t like the heat and the plastic can melt).

 

Adjust the LED’s so they point forward nicely, and check once more that no short circuits have appeared.


Put just one contact together with the battery, and swing the LED-box over the other contact - and see - the three LED’s light up! Just swing back - and you have an integrated switch.

 

The LED’s in this application will not light up fully, they need almost 4 Volt to do that and here they get only 3 Volt - but I think it’s enough, three LED’s give a lot of light.
If you are brave (and rich) why not test with only two LED’s, they will not have a long life - but one hell of a light.

 

What about the magnet? Yes, glue it up on the wall, and your lamp will stick on it - and you always know where the lamp is.

 

But don’t do as I did - I put my lamp on the magnet before the glue was dry and so I had to pick it all up from the floor (but nothing broke - the construction is now tested in both function and strength).

Greetings from P.O. in Sweden - comments welcome for the project, but not to my spelling and grammar ;)