Multicolor LED Circuit for Disk Drive Status

Description

Most PC enclosures provide only a single LED to indicate hard disk access, with the LED being connected to the motherboard via a two-pin connector. However, this LED only works with IDE drives, and if a SCSI disk controller is fitted, its activity will not be visibly noticeable. This small circuit remedies that problem using a multicolour LED. The activity LED for the IDE interface is usually driven by a connected device via one or more open-collector stages.

CNY17-2 Optocoupler

The CNY17-2 is a common optocoupler used for isolating electrical signals. It consists of a phototransistor and a Darlington transistor combined in a single package. This allows for the transmission of signals between two circuits without direct electrical connection, preventing noise and interference. Its use simplifies the design by integrating both components into a single package, reducing the circuit’s size and complexity. The CNY17-2 is a popular choice for applications requiring signal isolation, offering reliable switching and protection against electrical disturbances.

Dual LED

A dual LED is a LED containing two separate LED elements. It is commonly used in this type of circuit to display activity from two different interfaces. The dual LED has a common anode, which is a crucial element for proper operation within this circuit design. This design offers flexibility, allowing the circuit to respond to signals from two distinct sources, enhancing the diagnostic capabilities of the system.

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