Vilkkuvalot part 2

I had some requests about making a system to place hd led into the keyboard. Too simple so I used counter and timer ICs to make this little gadget.

	Basic idea is to have an "animation" playing when your computer is accessing your hard drive. We use a basic circuit that rotates 10 leds in sequence. The timer chip (555) is used to give us an constant clock pulse. This way the animation plays even when the system is constantly reading the disk. When there are some random reads these pulses will rotate the animation by themselves. If there are a lot of these short pulses the animation literally fly :) We use opto-isolator (TIL198) to separate our circuit from the rest of the computer system. In this way we are protecting the system if something goes wrong in our connection (if?). In the little picture at upper left corner is a basic schematic how to connect the center led in our circuit.
	Sometimes it's best not to show your solders but here it goes. I can only assure you that it really works :) I had to make this as tight as possible. Managed to do that quite well. At the left you can see the brown cable that is used to bring the signal from the motherboard's hd led connector.
	As you can see, there isn't so much spare space. I took +5 volts directly from ps2 connector.
	It would be much easier to assemble this if you choose a different kind of symbol to animate but I managed to get all the wirings done.
	Wow, it worked. When I hear my system reading from the hd, I can see those 10 leds go in circles. If you choose some other color for the leds, remember to calculate right values for the resistors.
	Sorry for the jumpy animation. This sequence is made out of mpeg movie. Note that this animation shows you the sequence as it would be when your system is reading your hd at the constant rate (your hd led would be lit all the time).

So this kind of project this time. It took me couple of days to alter the schematics for this and to solder it together. At least I can say that there isn't many of these kind of gadgets floating around in a world. Hope this inspired you to do something similar for your computer. :)

Questions and comments.

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