K.  Walraven
About the article

White LED Lamp

White LED Lamp
Nowadays you can buy white LEDs, which emit quite a bit of light. They are so bright that you shouldn’t look directly at them. They are still expensive, but that is bound to change.You can make a very good solid-state pocket torch using a few of these white LEDs. The simplest approach is naturally to use a separate series resistor for each LED, which has an operating voltage of around 3.5 V at 20 mA. Depending on the value of the supply voltage, quite a bit of power will be lost in the resistors.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

R1 = 1k?2
R2 = 68?
C1 = 100µF 16V radial
C2 = 680nF
C3 = 100µF 63V radial
L1 = 200µH 1A
D1 = Schottky diode type PBYR745 or equivalent
D2-D5 = zener diode 10V, 0.4W
D6-D15 = white LED
IC1 = LM2585T-ADJ (National Semiconductor)
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