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1  Using Arduino / Project Guidance / Re: varying frecuency of a PWM on: June 16, 2012, 10:27:32 am
I am on very thin ice here, but the "Arduino Cookbook" by Michael Margolis includes some sub chapters in chapter 18 about changing the PWM frequency. I just bought the Kindle Edition, and combined with my gigantic lack of knowledge regarding the Arduino I don't know if this  make any sense but:

In the mentioned chapters he use the term "prescale factor", accoding to the book TCCR1B ( timer 1) have a table showing the following columns, TCCR1B Prescale Value, Prescale factor (divider), Frequency:
1  1    312500

2   8    3906.25

3   64    488.28125

4   256    122.070......

5   1024    30.5175.....

The sketch in the example use the Serial Monitor so you can type in a digit from 1 to 7 to choose the frequency. The TCCR1B is the only register mentioned for timer 1.

And that is all I understand, sorry if I only added to the confusion!   smiley
2  International / Scandinavia / Re: Arduino + ethernet sende alarm ved indgang on: June 15, 2012, 12:41:03 am
Du har selvfølgeligt tænkt på at computeren kræver strøm ved dette strømudfald ... og det også gælder dine internet router, Arduinoen osv.

.....
Principerne i det du vil er nemme nok (hvis vi har forstået dig ret) - men detaljerne er besværlige. F.eks. de præcise måde Arduinoen kan se at det er HPFI der er faldet ud, og ikke bare en sikring er sprunget ...

Jeg har ikke set en færdig opskrift, men hvad har du fundet af del løsninger? Hvad mener du med "el tavlen har Ethernet"?

Det var også mine oppfølgende spørsmål.  smiley

Jeg antar at HPFI er det samme som i Norge kalles en "jordfeilbryter" (det kan se slik ut ifølge artikkelen om HPFI på dansk Wikipedia).
Antar videre at man via en form for strøm- eller spenningsdetektor kan lage et interface mot Arduino? Men uten flere detaljer er det vanskelig å si.
3  International / Scandinavia / Re: Arduino + ethernet sende alarm ved indgang on: June 12, 2012, 03:42:54 pm
Hei!
Det er nok nødvendig med litt mere informasjon før man kan svare på ditt spørsmål. Har du et diagram eller tegning som viser hva du ønsker å gjøre?

Men, hvis jeg har forstått din post korrekt så ønsker du en løsning der:

HPFI/eltavle -->Arduino-->Ethernet--->PC-->sender email

Er dette korrekt?

Tenker du å benytte en Arduino pr eltavle (med en eller flere HPFI)?
4  Using Arduino / General Electronics / Re: LED matrix and button matrix on same pins? on: June 12, 2012, 01:14:03 am
I imagine (in my head it seems doable anyway) you probably could solve this by using some kind of "bus structure" combined with 3-state latches/buffers and some other logic preventing you from enabeling different latches at the same time.

I' gonna say NO.   It might be possible, but probably not practical...  Maybe it could be done with some kind of additional hardware that switches between the buttons & the LEDs, so that at any moment either the buttons or the LEDs are connected/working. 
But I'm with DVDdoug on this one, its gonna get complicated...fast!  smiley
5  Using Arduino / General Electronics / Re: MC7805ACTG getting very hot on: June 08, 2012, 12:39:37 pm
Is your input voltage 9V like the schematic reads ?

You can test the regulator without any load, it should not get hot at all - if it heats up - something is wrong.

I don't know where you got the 330nF from - 100nF on each side is perfect for at 78xx-regulator.

Yes, its 9V from a wall wart.
It don't heat up without load, but thanks for the tip!
In the datasheet its recommended 0.33uF on the input side, in my head that translates to 330nF.

With 9v on the input side of the regulator and 350mA load, the regulator will dissipate (9 - 5) * 0.35 = 1.4W. So if your heatsink is 31C/W then you can expect the temperature of the regulator to rise by 31 * 1.4 = 43.4C. So at room temperature, you can expect the regulator to run at about 65C.

If the input is an unregulated 9v wall wart, you will probably find that it produces somewhat more than 9V when loaded well below its rated load, which will increase the power dissipation in the regulator further.

I guess 65C would feel pretty hot, so its probably normal.
The 7805 is rated up to 1A....maybe I should test it, and then roast some marshmallows     smiley-twist

Thank you both for input and help!

Cheers
6  Using Arduino / General Electronics / MC7805ACTG getting very hot on: June 08, 2012, 11:21:51 am
Hi!

A question regarding working temp of a MC7805ACTG.
In an attempt at a reboot...or rather a resurrection (we're talking night of the living dead here) of my long-time dormant and half-forgotten knowledge of basic electronics I decided to put together a simple voltage regulator, see attached drawing, to power my first Arduino project.

The 7805 is connected to a 31C/W cooling fin (is that the correct English word?), and I don't have a 0.33 uF capacitor at hand, hence the three in parallel at the 9V input side.

So my question is this:
At 150mA at the 5V side the cooling fin is lukewarm, but if I increase the load to 320-350mA it gets so hot that I only can touch it for couple of seconds.
Is this normal, or have I botched something?

BTW, the purpose of the LED is just as a simple power indicator, I've tried with it disconnected also, same result.

Cheers
 
7  Using Arduino / Project Guidance / Re: How to start a PC program using a switch on: May 26, 2012, 01:56:55 pm
I have limited knowledge of this but you probably could solve it using RobotBASIC also. A book I've just started reading about the Arduino and RobotBASIC have some examples that sounds very similar.
8  Using Arduino / General Electronics / Re: Datasheets, reliable websites, or available ebooks on: May 21, 2012, 02:00:16 pm
What is it about datasheet sites that they have to be so bloody hard to get information?

Half the time there are 20 large/flashing/graphical links to crap you aren't interested in and the real link is in 6 point text at the bottom of the page (if it's there at all).

I don't think alldatasheet.com is that bad but as you say you do have to load about 3 pages to get the PDF which is a pain, it's clear enough, just annoyingly indirect.

Thank You Sir, I second that one!!!

The sites are driving me nuts exactly for that reason!

Thank you to all posters, links and tips are meticulously preserved for future reference!  smiley-grin
9  Using Arduino / General Electronics / Re: Datasheets, reliable websites, or available ebooks on: May 20, 2012, 01:12:32 pm
Thank you, added to my list of bookmarks!
10  Using Arduino / General Electronics / Re: Datasheets, reliable websites, or available ebooks on: May 20, 2012, 02:40:41 am
Thank you for your answers. Browser bookmarks updated  smiley
11  Using Arduino / General Electronics / Re: Datasheets, reliable websites, or available ebooks on: May 19, 2012, 01:26:16 pm
A last question:
Is it feasible to talk about establishing an open source/no profit - wikipedia like site for datasheets??

cheers
12  Using Arduino / General Electronics / Re: Datasheets, reliable websites, or available ebooks on: May 19, 2012, 12:18:18 pm
Thank you RuggedCircuit, the guide is download and reading commenced!  smiley
Appreciate to hear that i am not the only one struggeling with this!
Cheers.
13  Using Arduino / General Electronics / Datasheets, reliable websites, or available ebooks on: May 19, 2012, 11:54:44 am
Hi!
Some questions regarding where to get datasheets (appologies if this is posted in the wrong forum).
I've been searching on the net for datasheets, especially the 7400-series. But either I am doing something wrong, or there is many "false positives". When searching for datasheets I get a lot of links/hits in Google, DuckDuckGo, "insert your search engine here", but none of them have the datasheet I'm looking for ( is this some form af search engine manipulation?).

So if someone could point me in the general direction of:

1 Sites that have a COMPLETE archive of datasheets for the 7400- and the 4000-series ICs.

2. Sites that have complete datasheet books in ebook format (for my Kindle).

I would be eternally gratefull. Don't mind if I have to pay for this, but just can't find them!!! 
 smiley

Cheers
14  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet shield made wireless through laptop? on: May 18, 2012, 04:06:27 pm
Depending on what setup you have, you might get by using "Internet Connection Sharing" in Windows 7. Search for windows 7, internet connection sharing, using ics and so on.
15  International / Scandinavia / Arduinoentusiaster i Norge on: May 16, 2012, 07:19:39 am
Hei!

Kryssposting er ikke god skikk og bruk, men håper likevel jeg slipper unna med en lenke til en post i Community - Local Groups.  smiley-grin

http://arduino.cc/forum/index.php/topic,106081.0.html

Noen som kan være interessert?

Ha en solfylt 17.
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