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316  Using Arduino / Project Guidance / Re: Slow discharge, bad for atmega328? on: July 27, 2011, 02:10:47 am
A pot. Does that affect your answer?
317  Using Arduino / Project Guidance / Re: Slow discharge, bad for atmega328? on: July 27, 2011, 12:21:04 am
Quote
A what?
A trimmer

Quote
One second is a long time, though.
Yep. I'd say at the very least 2/3 of a second.

Quote
Are you referring to the Arduino (no, it's fine), or the wallwart (it's likely fine, too)?
I was referring to the ATmega328, as the subject line reads. So if it(the atmega) is ok then thats good news. Thanks.  smiley-wink
318  Using Arduino / Project Guidance / Slow discharge, bad for atmega328? on: July 26, 2011, 06:35:09 pm
I have a standalone atmega328p connected to a wallwart through a 7805 voltage regulator. The atmega is directly powering 6 20mA LEDs and nothing else, just reading a trimmer. I have it plugged into a remote wall socket to directly cut the power and I noticed it take about a second for the wallwart to discharge and turn off the atmega. I assume the current is slowly decreasing in this time.  Is this bad for it? Is there anything I should do to improve it?

Thanks
319  Using Arduino / General Electronics / Re: 595 shiftout capacitor on: July 17, 2011, 04:20:09 am
Thanks guys... Can I ask then, is this tutorial wrong also about the two capacitors on the oscillator pins of the atmega?

http://arduino.cc/en/Main/Standalone
320  Using Arduino / General Electronics / Re: Best way to switch off this power supply on: July 16, 2011, 06:25:57 am
I'll give that a try. Thanks.
321  Using Arduino / General Electronics / 595 shiftout capacitor on: July 16, 2011, 05:55:19 am
I'm using this tutorial to use my shift registers. The text says to use a 0.1"f capacitor on the latch pin and the schematic image says 1uf. I've been searching for the past hour or two for another example that includes a capacitor but I can't find anything. What am I supposed to use?

thanks
322  Using Arduino / General Electronics / Best way to switch off this power supply on: July 14, 2011, 03:21:01 am
I'm working on a Nixie Tube clock and I plan on having it switch off at certain times. I was originally just going to send an unusable code to the decoder to turn them off until I just realized the little neon lamps are directly wired to the +170v. I was thinking it would just be more efficient to switch off the power supply to take care of the nixies and the lamps at the same time. I am using this 555 timer power supply. It will be supplying about 17-20ma but I wasn't sure if the power supply itself uses up more current. I was wondering what the proper way of switching off this PSU would be. I figured I could just cut the +12v but I wasn't exactly sure what things I need to consider to decide how I do that.

Thanks
323  Using Arduino / General Electronics / Re: Do I need a resistor for these nixie tubes? on: July 11, 2011, 04:42:20 pm
Thank you
324  Using Arduino / General Electronics / Re: Do I need a resistor for these nixie tubes? on: July 11, 2011, 04:39:06 pm
So for 170v I'm wanting 68Kohm? does that sound correct?
325  Using Arduino / General Electronics / Re: Do I need a resistor for these nixie tubes? on: July 11, 2011, 04:29:54 pm
The "rated current" is "2.5mA (0.3mA for DPs)" But that's the only info I can find. Is that what I'm looking for or do I need to keep searching?
326  Using Arduino / General Electronics / Re: Do I need a resistor for these nixie tubes? on: July 11, 2011, 04:20:52 pm
Ok. So although I have the correct voltage, I need to limit the current? How do I choose a value of resistor? I only see info on calculating for LEDs.
327  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?

Thanks
328  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.
329  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.
330  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?
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