Nobody makes IDE LED assemblies, nobody even talks about how to make them. So here's the information I've put together on making my own IDE activity LEDs.

The schematic is available here: [pdf] [dwg].

Parts required:

• 2 - NPN transistors (2N3904 or other common signaling transistor)
• 1 - 10kΩ 1/4 watt resistor (Brown Black Orange)
• 1 - 3.3kΩ 1/4 watt resistor (Orange Orange Red)
• 1 - 100Ω 1/4 watt resistor (Brown Black Brown)
• 1 - 2.1v 30ma LED (Resistors can be adjusted to make almost anything work

Of note: This circuit only shows bus activity, with the addition of a diode I might be able to make it indicate a single drives activity. The Signal line in the circuit should be connected to pin 39 on the IDE bus.

A big thanks to CanyonMan, who told me the theory of transistors and pointed out that I was remembering a lot of my DC theory wrong. Also pointing out what a common NPN is, and in general keeping me from being an idiot while trying to do this.