LED Torch-Lamp

I don’t know how many LED torch lamp I had bought altogether. (not mention Christmas lights :-D)

Here the photo of some torch lamp still I have. —– though, with my bad habit, as often I

disassemble them and utilized it for another purpose, many of them are no longer here.

In the left photo, top is a torch-lamp made by OSRAM using 5 ordinary ( 5mm white ) LEDs

powered by 3xAA battery which I bought 8 or 9 years ago. (but I discarded outer casing which was

too bulky )

The second in the photo was made by Ansman, which is using Hi-power Lumiled 1W LED

and 2 lithium battery = it’s mean powered by 6 volts (current was regulated by a resister) —–

quite bright but, as it use lithium battery, very expensive to run.

non

In the right photo, which I found at Tesco was also 1W torch, but using only 2 AA battery !

LED ( Light Emitting Diode ) is, as the name suggests, a kind of semiconductor diode.

To make a diode start to emit the light ( Photon was emitted) it is necessary to give the high-enough

electric energy = higher than so-called Forward Voltage which is for White LED about 3.5V, therefore

if it was powered by the ordinary battery, it is necessary to use minimum 3 batteries (1.5 x 3 = 4.5 V

—– then the LED will work until the voltage drop below 3.5V)

The Tesco torch-lamp which was powered by only 2 AA batteries mean, it is having an electronic

circuit called DC-DC converter which rises the voltage from 1.5 x 2 = 3 V to

more than 3.5 V. = And in fact this circuit can keep out-put voltage near constant 4V until the

battery become almost empty.

And this torch light is using hi-power 1W LED made by Cree. Even more surprise, this torch was

sold £5  (can you believe ?) = So, I bought 4 of them at once. 😀

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—– But funny story here was, as this torch lamp is able to drain the battery until it is completely

empty = on the end of the life, the internal pressure of the battery rise = battery become fatter =

stack inside of the chamber. (Really a hell to pull the stacked batteries out. :-D)  Battery maker

wanted to make their M-H battery having higher capacity (without using rare earth material)

therefore, the easiest way to achieve this is, to make the battery casing larger and thinner.

In the same time the manufacturer of the torch-lamp body wanted to save the material,

therefore made it to the minimum size, just enough to accommodates the standard AA battery.

= this is the situation, a trouble was waiting to happen  😀

—– Yet still, the reason why I bought 4 of them is to make a video-light kind of device.

= If I use only its light head and having separate battery box, it wouldn’t give any trouble.

( 4 W video-light with DC-DC converter which gives constant out-put, for £ 20 is a bargain ! )

Same as Tesco’s torch-lamp, photos above, this LED torche are also using only 2 batteries

= to say, second generation LED torch-lamp.

= It came from Lidl with £15 price and using Cree’s 3W LED.

3W mean, LED draw almost 1A current, hence it needs to use 2xD type battery and quite

solid aluminum structure with water proof O-ring. (pretty heavy though, it is blindingly bright,

and thanks to a built-in mirror the light can concentrate to narrow 5 degree = can see 50m away)

This one, photo left, was also from the Lidl. But this is a cheaper plastic version and a cost £3.

Yet still this is 2xAA battery type. In the photo you can see a LED and a Switch-mode DC-DC

converter circuit.  In the circuit-board, round black component is a coil to induce high voltage, and

together with 2 transistors (one oscillate and other is acting as a feed-back comparator to stabilize

the voltage) supply the power to a LED. (round aluminum block under the LED is a heat-sink).

When the battery is new and giving 3.2V, it supply 130mA 3.5V to LED and even the batteries are

nearly the end of life = 0.8Vx2, converter still give the same 3.5V though much reduced current,

10mA therefore the light out-put is not as bright as on the beginning (still usable).

(This LED is about 1/2 to 1/3 W —– 3.5Vx0.13A= 0,45W on the paper, but it seemed LED is not

a genuine Cree = cheaper copy ?) = Still, this one could be a best buy

= second generation LED torch for £3 !

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Yet still, the battle in a market is so fierce, a torch-lamp, photo right,  looks very ancient which

is using 3 LEDs was found to be also 2xD type which cost whopping  £1 only ! ! !

By using 3 standard LED, heat is not much a problem and 0.1W each x3, the light out-put is more

or less the same as the other one.  The circuit-board has only 2 component with 3 LEDs

—– in one glance,  I thought they are 1 transistor and a register though, they are in fact,

transistor-shaped 3 pin microchip and a coil in a shape of register.

= it was a proper switch-mode DC-DC converter.

With an atmost mean simplification it managed to make a £1 products. (Wittingly or unwittingly)

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  In comparison to those rather elaborated approach,

  the photo left is the opposite.

  It was made in a meanest way —– it’s using

  3xAAA batteries in the traditional manner but uses

  no soldering at all but just push-fit, relying only

  on the friction = Still, if it is only £1 and as long as

  it works, who bother. 

  While using 9 LEDs, it has a reasonable brightness.

  —– But, my intention to buy this was, again for

  different purpose 😀 —– somewhat properly made aluminum

body which got ON-OFF switch and 3xAAA battery holder = it can be used like a battery case or

handle of another device.  Hence, I bought 10 of them. 😀

( to make such parts from scratch, it needs to have a lots of work, and it couldn’t be £1 )

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Whether, to use it as a Torch-Lamp or utilize part of it, they are very useful tool.

= Torch-Lamp is not only looking for a lost coin under the bed. 😀

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