How to use the computers HDD LED to control another circ

[Kookie]

Hey, can you guys help me build this circuit? I want to use my computers motherboard hard drive LED to control another circuit. I figure this would be the call for an opto-isolator. In my search I could only find two kinds of opto's, a transistor and a Darlington pair set up. (There should be all different kinds, but I can't seem to find them.) I'm forgetting my basic electronics here (years ago) and I am having a hard time figuring out how to use this transistor to do the work I want.

There are basically two different circuits I want.

1. I want to control this device: Its a scanner light http://www.directron.com/vs400p.html
Here is the spec that I could find on it: http://www.hpdistributinginc.com/PDFs/V ... 0Guide.pdf

I could hook up the scanner circuit to the 12V from the computers power supply. How do I get that third lead to ground through the transistor in the opto-isolator? I also want to light the HDD LED.

I put up this picture to show what I mean: http://mywebpages.comcast.net/Kookie/Scancir.jpg

2. The other circuit is just as simple. Replace the scanner circuit with a 12V motor. Yes a motor, LOL.

here's a pic: http://mywebpages.comcast.net/Kookie/Motcir.jpg

So, If I may, could I tap into your talents here to help me figure this out. I would greatly appreciate it! I hope I was clear about what I wanted to accomplish. I'm just not sure how to set up the circuit with the transistor. Or, if there is a better suited opto-isolator, or a different way all together. Thanks again.

[greg123]

If you just want a ckt to react when the hard drive LED is on, use a photo detector. That will trigger the transistor and can be used to turn on a relay to turn on your devices. <p>An opto would not work as the led would have to be in the package with the transistor<p>g

[Dimbulb]

Let me ask you if I understand correctly.<p>You would like to modify your computer with an LED display.<p>The display is an automotive accessory that has a string of superbrite sequential leds.<p>The unit will be triggered by a photo-diode that is light coupled to the read and write indicator from your your hard drive.<p>The photodiode (or photo-transistor) is buffered to latch on latch off the replacing what would normally be a mechanical. The effect is Micheal the talking car is in your house doing light shows while you are computing.

[Kookie]

Praise be! Responses. Cool. <p>Greg, Yes, absolutely a photo detector at the point of where the LED is, would be the simplest and most direct method of solving my task, while simplifying all the parameters I have concern with. Right on, but to me, that's the down and dirty way. Not that that's a bad thing, but that's the way you'd do it if you had to get it done right now. You know what I mean? Kind of like if someone came to me with this and said, "Have this done when I come back in a bit and I'll pay you... whatever." I could see myself cutting a hole, with a utility knife, in the plastic where the LED is. Placing my detector in the hurried hole. Maybe if its handy, placing a little glue for good measure, and wrapping it with tape. Then run the wires to the components, twist them together, and forget the solder for times sake because you realize that you have to reassemble everything that you took apart to get to that damned little LED. He'll be back any minute without any concern on how it was done, because he must be done with his beer by now. <p>Yeah, I know that's a bit sarcastic, but I was just trying to be funny in further saying that I'd rather tell the guy, "Well... that's going to be quite an engineering feat. This will take many days and will cost you up the ass." You know he's gonna go for it because he's a boob, and you make a nice neat, relatively over complicated, little box that easily plugs into your components that you will give to your friends as well.<p>Again I hope that amused you.<p>I don't understand your statement of:<p>"An opto would not work as the led would have to be in the package with the transistor"<p>An opto, which is typically an LED, that uses photons to trigger a relatively myriad of devices such as transistors, thyristors, jfet's, and my favorite if they could put it in a little tiny black box, a monkey pulling a string. If only huh? But, I think I know what your point is and I believe you misunderstood me in that I want to light the LED in the optoisolator as well as the HDD LED. <p>My concern there, in keeping with the theme of over-complicating this somewhat, is driving basically two LED's off the motherboard. The existing LED and the LED in the opto. I have an NTE3041 (http://www.nteinc.com/specs/3000to3099/pdf/nte3041.pdf) which I believe requires about 60mA, and from the data sheet, I'm not sure at what voltage. I would assume like a typical LED around 2V. (One MB I tested puts out just that, 2V) I'm just paranoid in ruining an expensive MB by drawing too much current lighting two LED's in parallel. Really, I'm sure it shouldn't be a problem, but I thought someone might know for sure. In my drawing, I speculated that I might have to drive the existing LED from the 12V side of the circuit.<p>1206DX:

simply:<p>Q: You would like to modify your computer with an LED display.
A: YES<p>Q: The display is an automotive accessory that has a string of superbrite sequential leds.
A: YES, I believe so<p>Q: The unit will be triggered by a photo-diode that is light coupled to the read and write indicator from your hard drive.
A: Yeah, right on<p>
Q: The photodiode (or photo-transistor) is buffered to latch on latch off the replacing what would normally be a mechanical. The effect is Micheal the talking car is in your house doing light shows while you are computing.
A: Yes, I would assume so, and NO, not really. Although the sequential light thing does resemble the knightrider crappiness, it is more tended towards its predecessor (and a hell of a lot cooler in my opinion) the Cylon thing. "By your command.", thing, ya' know. If you seen how I'm doing it you might think its kinda cool. Well, at least a chuckle I hope.

[josmith]

In your diagram scancir you cannot put two leds in parallel without isolating them with resistors.<p>In the motorcir diagram your hdd led won't light because it's on the ground side. It should be in parallel with the motor with it's own series resistor.<p>If this is a retrofit for the front of a computer using a detector would be good since it would avoid any surgury on the computer. It could be a module that sticks over the hdd light on the front of the computer. The module could either be the entire divice or a trigger module with an led on the front to replace the covered up led and a wire out the side to the main divice.<p>[ March 29, 2003: Message edited by: josmith ]</p>