When I first took a look at this HDD Eyez project done by Jani ‘Japala’ Pönkkö over at MetkuMods I was thinking big deal, a few flashing red LEDs but the cap does some nice smoothing and results in a mesmerizing display.
Via: Hackolog
“We receive pulses from motherboard’s hdd led header. We get the pulses by removing the wire that goes to the original hdd led and replace it with our own wire that leads to our circuit. Optoisolator will charge the capacitor that is connected to the base of the in-built transistor. When the hdd activity gets faster, the ‘ACT’-led will start to shine more brightly because the charge inside the capacitor is getting higher. After this, when the activity dissapears, the capacitor will start to discharge via the base “leg” of the transistor and keep the led lit. When the charge of the capacitor goes slowly down, the led will get dimmer and dimmer and finally stop shining completely.”
