Hard Disk Drive Activity Metre

Here i had been working on this project for a long time and finally i was able to compile a working version of the HDD activity meter. The project that i will be showing, is fully tested and working. In fact i have installed in my computer and those interested and who want to have unique gadgets, this is the best project for you all.
This is also a unique project as because which searching in the search engine of instructables i could find none.
The project is quite a simple one and any one who can read schematics can easily assemble one from scratches. What this gadget does is that it tells the activity of the hard drive. In a company enclosed PC there is only one LED given to show the status of the hard drive, but now through this project you can have about 10 LED's to show the activity of the Hard Drive.
And each of the LED's have independent control over the other. So lets start by selecting what are the raw materials needed.

Materials Needed

• PCB board, (can be of any type).
• 10 LED’s whatever color you may use.
• IC- LM3915 or LM3914
• Optocoupler CNY17
• CAPACITOR
4.7uF/16V
• RESISTANT
10K POT type (Variable)
2.5K POT type (Variable)
1K ¼ watt
1.2K ¼ watt
3.9K ¼ watt

This are the primary things that you need to complete the working PCB and how you are gonna enclose the whole board completely lies on your ingenuity and skillful thinking.
For me I enclosed some of the LED’s using neon lighting technique and some I just drilled straight to the enclosure of my PC. You can see a video given in this instructables.
Actually I tried with the two versions trying to get the better position of the LED’s and I am showing both the position in the video. This is my first Version.

Circuit Description

Coming back to the project and giving some technical details. Our source signal that we will be extracting is from the motherboard of the PC will be from the two wires going to the HDD LED. The +ve and the –ve wires will now be going to Optocoupler CNY17 which will be acting as a sensor.
And the heart of the circuit lies in the IC- LM3915 or you may use LM3914. This IC’s are generally used as voltage comparators and here it will be driving the LED’s. The boosted signal that is received from the optocoupler CNY17 from pin 4 will be going to the signal pin 5 of IC- LM3915. Thus when there according to the activity of the Hard Drive there will be fluctuation of the voltage and accordingly the LED’s will jump.
There are two modes in this IC. One is the Bar mode and the other is the Dot mode. In Bar mode you will see that all the LED’s will glow along, and Dot mode is that you will see only one independent LED glowing from the bottom up. You may use either one. The only thing you have to do is when you give positive voltage to Pin No. 9 it will act as a bar mode and if you cut off the supply voltage of this line the LED’s will act as a Dot mode. If you want both modes to be accessible like I did you need to just add a switch to this pin connecting the +ve supply.
I suggest that first you assemble all the components in a Breadboard as it will be easier to for beginners.
After completion you can connect it to your motherboard HDD LED line and power it up. I suggest you don’t use the PC Power supply as it would ease the SMPS. You can make a separate 12v regulated power supply, or you may use a simple 12V lead acid battery like I did in my project. But be sure to have the power supply independent.

Analysis for the Project

Here I am showing how I made one from scratch and how my PC used to look when I bought it in second hand and how it has changed to a new Transformer Prime. Hope you guys like the instructables that I have posted and do comment or ask anything if you have any queries.

Hard Disk Drive Activity Metre