l'm in the throws of modding my machine and would like to increase the size of the LED. lt's currently (Ooops) got a yellow 3mm beast but l'd like to go for a 5mm one or possibly 2. Can you give me an idea of what sort of current might be available without resorting to any form of relay switching please. The mobo is an ECS P4S5A Many thanks Andy
An Opto-isolator is better then a relay in this case. THe current used from the LEDs is dumped directly into your harddrives. I would not put more then 90mA on that line.
The HDD LED connector on the motherboard is usually a 5V signal with a resistor for a 2V 20mA LED, meaning it can drive LEDs with a higher voltage, but they will get slightly less than 20mA
Actually you can put any led you like in place of the existing one, even a dozen Luxeon Stars in parallel, the onboard resistor will limit the current to a safe value (and your Luxeons will be a bit dim ). But if you want to set the brightness, use the optoisolator circuit. But if you decided to swap or bypass that on-board resistor, I'd not go over 15mA as it's probably a logic chip doing the switching. Normal HDD activity leds run at under 10mA, whatever their nominal rating.
