first post, not sure if I should post this here or in the electronics section, but anyways... I was staring at the hard disk activity light on my computer and realized that the standard blinking effect is boring and cliché, so I decided to make it do something more interesting. I wanted it to fade in and out depending on how active the drives are. After doing a little research, I made a modified soft on/off switch. Here is a schematic: R1: 4.7k ohms R2: 68 ohms R3: 68 ohms C1: 100 uF Q1 and Q2: any PNP transistors IN connects to the LED output on the disk controller/motherboard OUT connects to the HD activity LED +5V and GND connect to the power supply This circuit gives the activity LED a nice fading/slow pulsing effect, about 1 second in and out. Basically, it smooths the pulses sent to the light from the disk controller, so when the light would normally flash on and off, it shines at half brightness. I'd show pictures/videos of the final results, but I haven't soldered together the final version, and my electronics stuff is 85 miles away right now.
Hm, may have to give that a try... it's definately a cool idea. Of course my electronics knowledge sucks, but wouldn't you get a similar effect by simply adding a capacitor of some sort just before/after the LED (well, just use that)? "out" is the LED right?
i like the idea , its nice to see 'some' creativity on these forums, lately the 'modding' section posts are getting a little [cough] old [/cough]
Welcome to Bit, roboBOT. Looks very Electronic, all them symbols. Moving over. You're showing the transistors upside down (arrow always points positive to negative). The + input is a current-limited 5V and the - input is connected to ground through a diode and transistor switch which comes on with activity, so Q2 should be always off and can be eliminated AFAICS. Q1 will switch on with activity and do all the business, all you need from the mobo is the -pin trigger signal.
Good idea. Makes me think of the HDD activity meter article that used to be on bit-tech. That was a pretty awesome mod
Yeah, I might have messed up the schematic. I did it in Paint in 5 minutes, and I'm not exactly an electronics expert. All I know is that what I did worked. I forget which type of transistor goes which way, but I did have the collectors connected to +5V. The transistors had an "A" and then some numbers printed on them. One more thing: if you replace Q2 and the input with just a regular rocker/push-button switch, it works as a soft on/off switch for other stuff. You might need to adjust R2 and R3, though.
or you could use my adaptation on the hdd act meter with less risk of damaging the mobo? oh I forgot I edited the end to include a transistor to provide the current required for the LED's I've used.
That's the circuit for the light-up skull mod, isn't it? I looked at that, and it seemed overly complicated for what it does. But then again, I thought the project was starting to get a little complicated when I found I needed a second transistor and about 2 hours of trial-and-error to get the component values right. That 4N25 thing looks like it might not be a bad idea, but I don't already have one, and I wanted to work with parts I already had. The transistor switch should provide the isolation from the rest of the circuit that the mobo needs, though. It's better than just hooking the output in directly (which doesn't work anyways).
aint there away to do this using only one transistor and a cap? i thought i had a schematic figured out once but now i cant remember it. I was going to make a dome light fader for my pos car just like the one fancy cars have
OK, so replace Q2 with a photoisolator. Input goes to the LED leads of the photoisolator, and if the photoisolator has a photodiode, it goes across where the collector and emitter of Q2 used to be. If the photoisolator has a phototransistor, then connect it like DarkInferno did.
