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1  Using Arduino / Motors, Mechanics, and Power / Re: Silencing audiable PWM signals on: November 20, 2012, 02:13:27 pm
Your post doesn't say if your source of the PWM is an arduino, or even if an arduino is involved here.

The source of the PWM is the Melzi electronics on my new RepRap. The whole system is based off the Arduino Leonardo and utilizes the ATMEGA644P.

Edit: I got everything working just fine now thanks in part to users on the RepRap forums.
I forgot to mention here that I had a 12v regulator between the 19v Melzi electronics and fan. The first couple I was using weren’t quite in spec, but these new ones,  NJM7812FA, work like a charm. With that, the only other thing I included was a 35v 100uF cap on the fan's input.  
2  Using Arduino / Motors, Mechanics, and Power / Silencing audiable PWM signals on: November 19, 2012, 11:10:39 pm
I have this hefty 12 volt fan that has its speed regulated via PWM. It buzzes very loudly when in use and I wish to silence it.
A simple 25v 10uF capacitor on the fan's input lessons the sound slightly. An increase in capacitance lessons the sound more, but limits the range in speed control for the fan. (i.e. 50% duity cycle and up shows no change in the speed for the fan.)

The PWM frequency is 76Hz.
Finally, some brief specs on the fan are:
- Voltage range = 7.0 - 13.8
- Current = 710mA
- Input = 8.52w

Changing the supplied PWM frequency is not one of my options at this time.

3  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 28, 2012, 10:27:34 pm
Final update:

I got everything wired up and it all seems to work well. All I need to do now is add a bit of wood putty along with a few other touch ups, and its on to programming!  smiley-mr-green

Thanks everyone for the assistance.  I've attached a quick photo of the project in its latest state.
4  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 26, 2012, 11:36:27 pm
Ok, slight problem.
I just finished all the main circuitry for the build with only the incandescents left to wire up.
I've been running my example sketch throughout the build, it ran through each segment's output one at a time with no problems.
Now here's the problem I was worried about, I edited the sketch to turn on each output one at a time with an interval of about 200ms. After a very brief time with all 28 I/Os on, the 5v regulator overheats and shuts down. smiley-sad

I figured that the problem could very well be because I'm running  the poor thing off Arduino's maximum rated voltage of 12 volts. So I swapped the 12v supply for a 9v one. Results were better this time in that it did not overheat as quickly, however I shut it down after I clocked the PCB temperature underneath the regulator at a blistering 185F (85C). I don't really have any wall power supplies under 9v, nor would I like to use a second one next to  the already necessary 12v one, so I'm now wondering if there might be an alternative regulator I could use that would accept the 12v input.

On the other hand, the ATmega2560 seems to accept the LED and opto load just fine.

I just found myself a regulated 5v power supply. I paired it up with the 5v rails on the Arduino and everything seems to be getting along just fine... For now.  smiley-mr-green
5  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 24, 2012, 11:28:37 pm
Quick update,
Now that I have everything in hand, I decided to not include the planed seconds unit on this clock. I might instead replace it with a small pair of LED seven segment displays. If not that, then perhaps a single LED "ticker" that blinks every second.

Just to be sure, if I put a combined 580mA worth of LEDs and opto-isolators on the I/Os of the MEGA with less then 20mA each on each I/O pin, everything should be fine, right?

6  Using Arduino / Installation & Troubleshooting / Re: Arduino MEGA Digital I/O Issues on: August 24, 2012, 10:54:09 pm

Did you forget to configure the pin as an output?

Ya, that was the problem... I've been up for way too long..  smiley-sweat

Thanks, and sorry for your time. 
7  Using Arduino / Installation & Troubleshooting / [Solved] Arduino MEGA Digital I/O Issues on: August 24, 2012, 10:46:21 pm
I just got myself an Arduino MEGA R3 for an upcoming project and every digital I/O pin except pin 13 falls at roughly 3.5 volts with very little current.

For example, while running a basic blink sketch on all pins, I can connect an LED to pin 13 through a 220 ohm resistor and It will illuminate just fine. However, if I use that same setup but swap pin 13 for say, pin 12, then the LED will light up very very dimly and the voltage will drop to ~1.5v
Choosing a different ground pin or different LED does not solve the issue.

Any ideas?
8  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 23, 2012, 10:22:07 am
Can you point to the lamps you will be using? Where can you get them?? Sounds cool...  

The bulbs I'm using are the 130V 20W frosted T6-1/2 w/ intermediate base (E17)s.
I found mine on Ebay.

9  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 23, 2012, 09:49:38 am
I'd also consider replacing the bulbs with ultrabright LEDs instead. Using 15,000mcd whte LEDs drawing only 20mA each, arranged as strings of 3 or 6 or 9 per digit and driven from 12V with ULN2803 as the buffer, would be quite bright also and use less energy.

This clock is more of a novelty. The incandescents and relays are a key part of the design.
Also, the input waveform for these frosted 130v 60Hz bulbs will be chopped thanks to some household light dimmer(s). This will maintain a comfortable brightness for a kind of warm look.
10  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 23, 2012, 06:50:26 am
I would use 6 TPIC6B595 latch/drivers...

I was looking at those, but there were two problems I thought I may have with them.

First of all, I can't seem to find any decent tutorials for these 595s. They are fairly new to me and I would have to figure out how to convert a numerical value to a specific pattern of I/O to drive each of the relays. I also already have the code figured out for my original idea that didn't require these 595s.

Another issue I just thought of was that I'm using a ChronoDot for the time keeping, and it uses those same clock and latch pins that these 595s would otherwise seem to use and I'm not sure if they would like to share with the ChronoDot.

11  Using Arduino / Project Guidance / Arduino MEGA current draw predicament on: August 22, 2012, 10:10:43 pm
Hi all,
I'm building this larg-ish scale digital clock using a series of six inch incandescent tube lamps positioned in the form of several seven segment displays. Clear-case relays will be controlling the 120v lights (dimmed of course), and some Toshiba TLP621 opto-isolators will be controlling the relays. Finally, an Arduino Mega will be in charge of the opto-isolators.
There will be a seconds unit on this clock, and with that being said, 43 I/Os will be used. However, while only for a few seconds, a maximum of 32 pins will be powered high at any given time.

My concern is whether or not the Arduino will be able to power that amount of opto-isolators (32). Each opto requires 5-10mA, and from what I found, the MEGA can only supply a collective current of up to 200mA.

Another thing I have to mention was that my original plan included the use of 20mA LEDs wired in parallel with the LED side of each of the the 43 opto-isolators (220 ohm resistor included with each LED). I have since omitted these since it would most certainly exceed the current draw of the Arduino. I still have some other indicator ideas for the other side of the optos, but that would require me to order more parts.  Let me know of your opinion about this indicator idea.

Anyway, I simply ask whether or not the Arduino will be happy when powering all those opto-isolators. It's also worth noting that, a 220 ohm resistor will be in series with each one.

12  Using Arduino / Installation & Troubleshooting / Re: Arduino Regulator: How hot is too hot? on: April 22, 2012, 09:43:00 pm
what about checking the datasheet of the mentioned regulators and see their normal temperatures ( with and without heatsink?!?)
That way you will start getting used to reading a datasheet.

I already did, Its upper limit is 125C. I was just worried because 63C seems awfully hot for the seemingly minimal stuff it's running. (Thinking there could be a bridged set of pins somewhere.)
13  Using Arduino / Installation & Troubleshooting / Arduino Regulator: How hot is too hot? on: April 22, 2012, 09:20:44 pm
When ever I run this Arduino UNO R2 + Ethernet Shield web server for more then a few minutes, I notice that both regulators become fairly hot. I also noticed that the regulator on the Arduino itself operates significantly hotter.

The regulator on the Ethernet Shield levels out at around 106F (41C), while the regulator on the Arduino tops off at 146F (63C), which is almost untouchable.
I'm supplying a steady 9v and nothing fancy is attached to this setup, only the Ethernet Shield's Wiznet chip and its few status and data LEDs.

If anyone can provide some info on whether or not this is normal, that would be great. This little web server may be set up as a long-term thing and I'd like it to last.

In advance, Thanks
14  Using Arduino / Project Guidance / Re: Altering files on Arduino+Ethernet web server on: April 14, 2012, 01:29:18 am
Quick update,

I just finished toying with some HTML GET/ commands (Commonly used in Arduino web servers to send text to an lcd through a web interface.) and I quickly realized how difficult this would be.
I'm sure there is another way to do all this, but currently, I am at a stand still.

I'm still open to Ideas though.
15  Using Arduino / Programming Questions / Re: Arduino web server and PHP on: April 12, 2012, 10:38:43 pm
I meant to ask if PHP scripts could work. Of course basic PHP text will.

For example, this PHP script prints out all files in it's directory.
Code: (files.php)
// open this directory 
$myDirectory opendir(".");

// get each entry
while($entryName readdir($myDirectory)) {
$dirArray[] = $entryName;


// close directory

// count elements in array
$indexCount count($dirArray);
Print (
"$indexCount files<br>\n");

// sort 'em

// print 'em
print("<TABLE border=1 cellpadding=5 cellspacing=0 class=whitelinks>\n");
// loop through the array of files and print them all
for($index=0$index $indexCount$index++) {
        if (
substr("$dirArray[$index]"01) != "."){ // don't list hidden files
print("<TR><TD><a href=\"$dirArray[$index]\">$dirArray[$index]</a></td>");

I know that can be done in the Arduino IDE, but this is about PHP scripts.
Also, the attached screen shot shows how the above code is rendered through an Arduino web server.
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