I've read the article on bit tech, about hdd vu meter, but from what i understood from the article, the 20 leds hdd meter version works with leds in pair, basically two raws of 10 leds, lighted at the same time. What i want is a full 26 led bar, hdd vu meter, with led #1 lighted when hdd activity is very low, and led #26 lighted when hd activity is very high, with all the leds between lighted when needed. Can this be built and can work as good as the 10 led version? Sorry if maybe i'm unclear in my explanation, but english is not my native lanquage.
yes, that is possible. Netional Semiconductor's website and datasheet says it is: - Expandable to displays of 100 steps looks like it's only possible in dot mode, not in bar mode...
What's the difference between dot mode and bar mode? What i want is like this, but with 26 leds on each side: http://www.youtube.com/watch?v=gn-0GpQUMYk Is this bar or dot mode?
In "dot" mode you need a small circuit change to turn the top LED of the bottom-half display off when it goes over its maximum onto the next IC. In bar mode no problem, every bottom-half LED stays lit when over its max, so the datasheet doesn't bother to bring it up.
Ok, i've made a mistake when i wrote the title of the thread. It's 26 leds, two raws of 26 leds each, not 20 leds, as i originally posted. I've edited all my previous posts to reflect this. I've made a quick drawing in Paint with my "awesome" painting skills, i hope it gets more clearer to you as what i want to do: I want each of the two led strips to light in parallel, like in that youtube video, posted in my previous post (#5). Is this dot or bar mode? Sorry for being such a newbie...
'Dot' mode a single LED in the column is lit to show the current high point. 'Bar' mode all LEDs up to and including the current high point are lit. Two columns from the same signal isn't a problem, the two LEDs are just wired in series. But you'll need three LM3914s for 26 LEDs. Get the datasheet, it shows how to cascade them.
The thing is someone else will built this for me, as i don't know anything about electronics (all i know is how to solder some leds and put resistors on them, nothing else ). The person i've talked to, said in the case of too many leds (greater then 10 or 15 leds), the signal would be too weak, and the top leds would never be lit, or something.
Try addidng a capacitor and by using 26 LEDS you May need a bigger Resistor and will proberly need to add more amp to it to power all that i'm going to say to have a beeter signal is shorten the cable length as much as you can but not that short that it'll won't be ablke to attach or the cables can be ripped off.
That's probably why the light in my attic is so dim. The electric has got tired going up so high. No, he's wrong. The LED current has to be reduced a bit in bar mode for all the LEDs, compared to what's allowed in dot mode, so the LM3914 chips don't overheat, but every lit LED in the column will glow at the same brightness.
Don't know, maybe i didn't understand what he was saying. Most likely... How much power will draw this meter from the psu? Does it require some sort of active cooling? Does it get hot?
