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| Thread ID: 28946 | 2003-01-05 22:19:00 | anyone who knows much about electronics... | tango (2697) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 111301 | 2003-01-05 22:19:00 | I have a big blue LED, and I want to be able to hook it up to the HDD indicator light, so it flashes and lights up the inside of my box and stuff (I have a window). Anyway I tried connecting the LED straight to the light output on the motherboard, but the voltage coming out is just under 4 volts. The LED's typical operating voltage is 10.5 volts, so I was thinking, I could get a transistor, and use it as a switch, and run the LED from one of the outputs of my power supply. Does anyone know what kind of transistor to use? and how to get it going? and also, is it ok to run the power supply connector, and the HDD light connector onto the same ground line? thanks. | tango (2697) | ||
| 111302 | 2003-01-05 22:25:00 | Is there such profession as a Computer Electrician? Maybe, you could try all of those people! ;-) | ~~~~~ s y ~~~~~ (2054) | ||
| 111303 | 2003-01-05 22:40:00 | LED's have to have the current limited by a resistor, otherwise the LED will instantly self destruct. You wont see any light, even briefly I am surprised by your comment of 10.5 volts, as most LEDs are in 3 - 4 volt range. I wonder if yours already has a series resistor internally??. YOU REALLY NEED TO KNOW! Most LED's require forward current of around 20 mA (milliamps, 0.02 Amps) for nominal brightness, any more can also cause failure. The voltage required is therefore dictated by the value of the resistor and the forward current. 20 mA from 12v supply, (assuming a 3.6v forward drop in the LED), means your resistor should allow 20 mA to flow with (12-3.6) = 8.4 v R=E(volts)/I(current) R (resistor value) = 8.4 (volts)/ .02 (20 mA) = 420 Ohms. Erring on the safe side, the nearest standard value is 470 ohms. However if the LED already has an internal resistor (its just that I have never seen one that has, but its possible) you need to know what its value is. Remember NEVER CONNECT AN LED DIRECTLY TO THE SUPPLY, WITHOUT A CURRENT LIMITING DEVICE IN THE CIRCUIT. Unless you want to buy another LED |
godfather (25) | ||
| 111304 | 2003-01-05 22:53:00 | *Listen to that 'Whooosh' sound as all that flies right over Chilling_Silence's head!* I would say that a New LED would be in order, as most are about 3V, but there are other things to watch out for as godfather has probably described in his post :-) |
Chilling_Silence (9) | ||
| 111305 | 2003-01-05 23:07:00 | haha yeah I guess I should have described the LED a little more... www.dse.co.nz that's it there. if you were to cut a mouse ball straight down the middle, one half of it would be about the size of the LED. I don't see anything about an internal resistor, but I was going to drop the voltage down to maybe 11 instead of 12 anyway. |
tango (2697) | ||
| 111306 | 2003-01-05 23:13:00 | Err.... URL seems to be a dud, taking you to the main page as per normal for DSE... | Chilling_Silence (9) | ||
| 111307 | 2003-01-05 23:18:00 | aaahhhh nuts....ok, go to the home page and search for Z4320 then click the photo to get a full description. |
tango (2697) | ||
| 111308 | 2003-01-05 23:22:00 | OK. It may or may not have an internal resistor, but its the CURRENT you MUST not exceed. If indeed it has just a high forward voltage, and no resistor, connecting 11v will still instantly destroy it. So will 10.5 probably. Now, as for lighting the case - well, it has a luminance of 30 Mcd. High brightness LEDs now have a luminance of 20,000 Mcd. Dont expect it to be very bright. I doubt it will show any "illumination of the case", you will be able to tell if its on or off though, by looking at the LED itself. Play safe, use a resistor for a start, try 150 ohms, 1/4 watt rating. |
godfather (25) | ||
| 111309 | 2003-01-05 23:33:00 | no no..I've already had it going inside my case. I've got it temporily connected to a 9 volt adapter, and it lights up the inside nicely. but I'll check out that stuff about current... | tango (2697) | ||
| 111310 | 2003-01-05 23:40:00 | Look at some of the superbright ones, they are only 5mm in size, but can be used as illumination in torches . They will certainly light your case, even in daylight, but must have a resistor in series . I do suspect your blue one has a resistor internally . Otherwise it would be dead . Its not common to have the resistor internal though so be warned if you try another type . I have torches here that use superbright LEDs, (6,000 Mcd) they are great, batteries last a long time . They require special electronics in the torch though . |
godfather (25) | ||
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