This is a cool computer mod which makes use of a customized hard drive LED and driver. It involves only a small amount of money while making the eyes of the skull glow. The HDD Eyez also fades in and out when there are some HDD activities. The schematic diagram of the circuit and the final outcome are shown below.
The HDD LED header of the motherboard provides the pulses by removing the wire that goes to the original HDD LED and replaces it with the wire that leads to the shown circuit. The capacitor that is connected to the base of the built-in transistor will be charged by the optoisolator. When the charge inside the capacitor is getting higher, the ‘ACT’ LED will start to shine more brightly when the HDD activity gets faster. The capacitor will start to discharge through the base leg of the transistor and keep the LED lit when the activity disappears.
As shown in the images below, a power LED and current-limiting resistor parallel to this was added aside from the basic circuit. The LED will be lit when the computer setup is powered ON since this will act as a power indicator.
Although there are lots of other items that can be used to stuck a few LEDs and make it glow, the skull was chosen which can be seen alongside with the circuit below. The back side of the skull is also shown. The skull can be placed or mounted wherever desired by leaving the screw in place. Otherwise a regular hacksaw can be used to cut it out to give a smoother surface to work with.
The holes for the light to channel through were made by using 2mm drill as shown below. A real force in drilling is not necessary since the metal on the thumb screws was fairly soft.
Hot glue is used to me the eyez where the nozzle of the hot glue gun is aimed to one of the eye holes from the back of the skull. The eye will be formed by giving the trigger a squeeze which is also applicable to the other eye. A more or less identical eyez can be obtained by using equal amount of force. The front and back side images of the HDD Eyez are shown below.
For the eyez to get the best possible glow from them, two 5mm LEDs were connected in parallel. More LEDs can be used because the power is being taken directly from the power supply of the computer. Compared to using the HDD LED header power only of the motherboard, more current can be taken from the PSU.
The effects are shown in real life from the following videos where an interesting, purple color is being given when the red LEDs are dimming. The circuit does not affect the motherboard in any way by using the optoisolator. Also, the circuit may be used to indicate LAN activity from the network adapter or keyboard activity or mouse movement, with some little modifications.