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316  Using Arduino / General Electronics / Do I need a resistor for these nixie tubes? on: July 11, 2011, 04:00:29 pm
I am using this power supply to power my IN-14 Nixies. Do I still need a resistor on the anode of the Nixie if the power supply is already providing the correct voltage? They work fine without it but then after reading a few articles mentioning the need for a resistor I realized it may still be necessary... Is it?

317  Using Arduino / LEDs and Multiplexing / Re: Lots of independant LEDs on: July 04, 2011, 05:41:23 pm
256 LEDs in total, 64 on at a time. 64* .020A = 1.28A for each scan.
318  Using Arduino / LEDs and Multiplexing / Re: Lots of independant LEDs on: July 04, 2011, 04:59:17 pm
I havn't actually chosen specific LEDs yet. I'm just going off the assumption that they will be approximately 20mA and that 16 LEDs on each 595 will have a load of approximately 320mA at max and each scan of my matrix will have approximately 20mA * 32 pins * 2 LEDs = 1.28A. It seems to me like the easiest way to sink over an amp would be a PNP transistor. Are my math and logic correct? Or should I approach this differently?

The thing about the 5940 is that I don't need full PWM. I just need a few levels of brighness which I can do with the matrix pretty easily. I'm afraid using PWM in a matrix would slow down the shiftout(requires mire info, right?).

I really only have a pretty basic understanding of all this so please forgive the difficulty I'm causing. I really appreciate all of everyone's help.
319  Using Arduino / LEDs and Multiplexing / Re: Lots of independant LEDs on: July 03, 2011, 04:04:36 pm
Since each scan on my matrix will have 64 LEDs wouldn't I need something much higher wattage to sink them?
320  Using Arduino / LEDs and Multiplexing / Re: Lots of independant LEDs on: July 03, 2011, 02:31:28 pm
Thanks guys. Unfortunately, a lot of these seem to be a bit out of my price range so I may have to just stick with the 595s. However I think I've got it mostly figured out. I can matrix 4x32 AND use that to get my low resolution PWM. I only need four levels of brighness so I just have to code them to only go high on ever certain number of scans. I'm going to check out that code when I get a chance though. Then, since I'm not looking for a ton of complexity, I can just have each side mirrored. That means 32 pins with 4 matrix scans split to 2 LEDs each. That's 256 LEDs with all the flexibility I need. I just need to make sure that 16 LEDs on one 595 is not too much current. Can I just use NPN transistors on each 595 pin to ease it's load?
321  Using Arduino / LEDs and Multiplexing / Re: Lots of independant LEDs on: July 01, 2011, 03:34:35 pm
Haha, whoops....

Anyway, I'm looking for maximum brightness. At least for the brightest ones. Then a few levels darker if possible. Sortof to create a comet trail look. I wouldnt want to split them up into more than 4 columns/rows because it seems like they would begin to get pretty dark after that. so maybe 4x32? Can I shiftout to 32 registers quickly enough for a matrix? And even better, could I cycle the matix quickly enough to fake PWM some of the LED's? For instance have four cycles, 1 LED High for all four, 1 for 3/4, the next for 2/4 and last 1/4....Could I shiftout 32 bits 4 times and have the 1/4 LED not appear to strobe?

322  Using Arduino / LEDs and Multiplexing / Lots of independant LEDs on: July 01, 2011, 03:43:29 am
A friend of mine is interested in having me make him an LED face for the front of his music equipment box thingy. It would be a pattern of LEDs that would mostly be controlled independently, although if necessary it could be wired up so that many share the same pins. I've only ever gotten as far as using 595's to shiftout to a few LED's so this is quite a step up for me, but something I'd really like to try.

I think we would be looking at a hundred or two LED's. My first question is, would it be a bad idea to daisy chain a whole lotta 595's? would I have to worry about lag or anything else? Is there an alternative to the 595 that provides more output pins so as to be more economical?

Another question is what are my options with PWM? Are there shit registers that support it? Or would it be possible to simulate PWM myself by shifting out rapidly? That seems a bit unlikely.

Anyway, he seems pretty flexible so I just want to get an idea of that could be done, and how I could approach it. I would really appreciate any info.

323  Using Arduino / Sensors / Re: Detecting human presence - LMI 878 IR detector on: June 27, 2011, 04:26:26 pm
The enclosure will be about 4x8x4 but most of that space will be occupied by components. So I was hoping for something as small as possible. I don't really know the exact dimensions I will have space for because I can't really move ahead until I figure out what I'm using.

Do the ultrasonic ones make audible noise? My experience with them has made them seem pretty noisy with clicks.

I think I'm gone try that component I linked above however I've still got those questions about it.
324  Using Arduino / Sensors / Re: Detecting human presence - LMI 878 IR detector on: June 25, 2011, 08:41:46 am
Yes I'm sorry, LHI878, I must've typo'd at some point and I've just been referencing it since. Any info on how to use this thing would be great but I'm about 90% sure it depends on additional hardware.

As for my range, like I said, I'm looking for movement in a room so 15 feet at least would be nice but I suppose as little as 10 could do. On the low end, as long as it could respond to movement two or three feet away that would do, closer than that wouldn't really be necessary. And for the angle, as much as possible would be preferred but as little as 45 degrees would be acceptable.

I don't need anything fancy. I don't even need to be constantly monitoring movement. I just need to wake up my clock with motion detection and have it turn off 10 or 20 minutes later unless it detects more movement and continues to wait for that amount of time after the last motion is detected.

I was looking at this:
However I am worried about the response time being 30s. If that means that I can only take a reading every 30 seconds that's fine. But if it means it takes 30s to report movement, that's no good for me. I'm hoping for the clock to wake up relatively quickly after it senses motion, like a few seconds at most. Also I wanted to be sure it has everything included to be usable with the arduino unlike as I suspect the LHI 878 does not.
325  Using Arduino / Sensors / Re: Detecting human presence - LMI 878 IR detector on: June 25, 2011, 04:17:03 am
Does anyone know about the LMI878? Should I be able to use it alone or is it useless without some kind of breakout board?
326  Using Arduino / Sensors / Re: Detecting human presence - LMI 878 IR detector on: June 24, 2011, 05:51:18 pm
That looks pretty good. The only problem is that the one that does the range I need is pretty big for my project. Also I'm wondering what the angle is, it seems like it just measures what's directly ahead because there's no mention of angle range. I was hoping for more like 90 degrees or more. I'll keep looking into them but I think these might not quite do it. Thank you though.

Also on second glance I realized the furthest range I could find was 5 feet which it much less than what will do for this project.
327  Using Arduino / Sensors / Detecting human presence - LMI 878 IR detector on: June 24, 2011, 07:38:30 am
I'm trying to detect the movement of people to simply see if someone's around, nothing fancy. Im using the LMI 878. I've got it wired: D to 5v via 10kohm resistor, S to an analog pin and ground to ground. I don't seem to get any usable response out of it unless I'm missing something. I suspect I need a special breakout board but I'm hoping not.

Regardless, I'm looking for an inexpensive, compact way to see if someone walks in front of my project. Preferably even if they are far away(across a large household room), and also preferably not set it off with a fan or something else moving. It's for the front of a clock so I hope for it to not look too awful. If I can do it with just this thing then that would be great, otherwise I would really appreciate some suggestions.

Thanks very much.
328  Topics / Device Hacking / Re: Harvesting an iphone on: June 24, 2011, 06:38:42 am
I figured that would be the case. thanks
329  Topics / Device Hacking / Harvesting an iphone on: June 19, 2011, 04:19:55 am
I was wondering if it would be a good idea to try to use an old iphone for its accelerometer or something else fun to play with or if the parts are too tiny and specialized to bother. Ive got an old iphone 3g with a dead battery and smashed screen. I know its still worth a few bucks in that state but not really worth the trouble of selling anymore. Has this been done? I couldnt find any info on removing and using an iphones accelerometer.

330  Using Arduino / Programming Questions / Re: CD4201B shiftin latency on: June 04, 2011, 08:36:14 pm
Ah, okay I see. But it seems just a bit beyond me, I'll try to find something that suits my needs and give it a try. Thanks.
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