Friday, October 8, 2010

DIY hard drive clock (part 2)

RGB LED light installation.

Any type of LED light can be employed for this clock design but since my discovery of affordable flexible RGB LED strip I use it in most of my LED based projects.
LED strip has self-adhesive backing and consists of easily separated sections and intended for 12V operation.
Every section contains 3 RGB LEDs with common anode, SMT current limiting resistors and soldering pads on each end.

Electrically all sections in the strip are connected in parallel so whole LED strip can be powered by connecting supply cable to any section. 

Flexible RGB LED strip and more rigid plastic base.

LED strip is too soft and flexible so I've made base ring from scrap plastic and stuck strip to the ring for reinforcement.

RGB LED ring completed.
Fortunately, 9 LEDs strip has the same length as circumference of the hard drive disk so LED ring fits perfectly inside casing.
Ring is secured inside hard drive with hot glue.

LED ring fitted inside hard drive casing.
Control cable for LED ring contains 4 wires:
 - supply voltage  +12V;
 - RED;
 - BLUE.

LEDs of selected color turn ON when corresponding line is connected to ground.

Power consumption for 9 LEDs at 12V:
RED - 43.75mA
GREEN - 32.5mA
BLUE - 34.8mA

All LEDs of one color are controlled by dedicated 2N7000 MOSFET switch (max current 200 mA).

RGB LED strip. Control cable connection.
(part 1)<--- DIY hard drive clock ---> (part 3)

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