Newbie needs help...has interesting questions!

I recently purchased two arduino duemilanove boards and a bunch of other accessories (protoshield kit, sensors, leds, lcd screens etc?). I am a programmer by profession so the sketches should come easy. But other than that, I’m completely new to all this? but I have heart and I have the passion for ths. I’m a die hard DIYer?
Here are a couple of questions that came to me. I haven’t actually started working on anything yet so, any kind of help would certainly be appreciated!

  1. How far will a signal travel along a wire? I’m asking because I am ultimately interested in making a home automation system using my Arduino and want to know how far I can place the different sensors from the Arduino board? How long can the wires be? And would that depend on the type of wires? What types of wires can I use?
  2. What is the relationship between voltage and audio? What kind of signal (voltage) is travelling through the wires that run from the computer to the speakers?
  3. How does one identify and gut out parts from an existing device? Is there a way of measuring and finding the voltage and current requirements of a part?
    a. I have a busted mp3 player from which I want to gut out and use the small LCD screen. How do I go about doing that?
    b. I have a Motorola Bluetooth headset that I want to gut out and use as a generic Bluetooth receiver/transmitter. How can I do that?
    c. I have a wireless mouse which I want to gut out and take the RF transmitter/receiver for general use with the Arduino. How?
  4. Like I said in the beginning, I’m ultimately interested in building a home automation system (multi-room audio, light control and sensors – temp, touch, vibration etc). How should I go about it?
  5. For now, I want to start by building a network cable tester. I have two RJ-45 connectors? can someone sketch me a drawing on how to go about it (it’s pretty simple in my head, the logic of the circuit should test for two things, whether the wires are crimped straight or as a cross-over cable)
    Thank you all!!!
    Nahom
  1. How far will a signal travel along a wire? I'm asking because I am ultimately interested in making a home automation system using my Arduino and want to know how far I can place the different sensors from the Arduino board? How long can the wires be? And would that depend on the type of wires? What types of wires can I use?

That depends on the signal frequency and the components on that particular circuit. RS232 - 15m (50ft) but only point-to-point, single wires RS485 - 1200m (4000ft) 32 drivers/receivers, twisted pairs, etc. Good starting point: http://en.wikipedia.org/wiki/List_of_network_buses

  1. What is the relationship between voltage and audio? What kind of signal (voltage) is travelling through the wires that run from the computer to the speakers?

The first question is something like :o. The second part: around 50-100mV. The rest is up to the power amp inside the speakers.

  1. How does one identify and gut out parts from an existing device? Is there a way of measuring and finding the voltage and current requirements of a part?

Well, first take a soldering iron and a desoldering pump. About the parts, there are usually the datasheets.

The rest (4, 5) - google.

Regards, thenoble66

Hello nahomt, welcome to the forum.

Lot of questions, i cant answer all of them ! But can try some:

  1. A wire is a resistance after all, electrons travel trough the wire with a cost: friction, causing some current being loss in heat form Resistance. If wire resistance is too much you can have some trouble (Arduino have a limit of current you can use in each pin, exceeding this value can cause damage to the Atmega chip). Atmega digital signal is TTL http://en.wikipedia.org/wiki/Transistor-transistor_logic and All standardized common TTL circuits operate with a 5-volt power supply, it uses the voltage as logic 0 and 1 http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/logfam.html. Not sure but i think if you respect the max current allowed in the Atmega pins and can achieve the voltage levels as show on the last link it´s ok.

  2. The relationship is higher the voltage signal to the speaker higher the sound it makes http://electronics.howstuffworks.com/speaker6.htm

  3. The best way Identifying parts is searching for it´s datasheets http://www.google.com.br/search?hl=pt-BR&q="ds1307"%2B"datasheet"&btnG=Pesquisar&meta=&aq=f&oq=

3.a. First you need to identify the type of LCD it uses and the right manner to wire it to Arduino and code to get it working, there are some LCD out-of-the-box libraries you can use for the most common ones (serial and parallel).

3.b. Dont have a clue. You will need to identify how the bluetooth is interfaced in the circuit and understand it´s logic. The best way IMO is to start from some bluetooth module.

  1. Start from here http://arduino.cc/en/Tutorial/Blink

Disclaimer: Im not an student or electric engineer just a hobbist, the answers provided may contain grotesque errors :slight_smile:

  • Buy an multimeter
  • Google is your friend

Good luck and have fun :smiley:

Salute,

Rodrigo

RS232 - 15m (50ft) but only point-to-point, single wires

I currently have 2 arduinos communicating quite reliably over 50m using software serial at 9600 baud over cat5 cabling with the cabling snaking through mains cabling and over florescent light fittings in a suspended ceiling. It was quite happy when testing running through a 100m reel still on the reel. Thats just the TTL 5v stuff used by the Arduino. If you turn the speed down you can get it to go further still. This was to get around the around the maximum 10m distance I could get dallas digital thermometers to work from the arduino. In a previous life we had "real" RS232 working reliably at 9600 over 250m

Using a ground, armored cable should be a way to go also.

Using a ground, armored cable

Not the right word it is in fact "shielded" not armored which implies it is bullet proof. Thought you would rather know. ;)

Thanks, pluggy

I currently have 2 arduinos communicating quite reliably over 50m using software serial at 9600 baud over cat5 cabling

You're right.

The distances I mentioned earlier are just taken from standards. Generally the standards are made to provide some good starting points for those who are relying on them. The technical limits stated in standards are not absolute maximum/minimum values, like in IC datasheets. Certainly, the more closely a manufacturer (hobbist) will rely on a standard, the more reliable will be his/her system. Am I right?

Thanks again. thenoble66

Not the right word it is in fact "shielded"

Sorry Grumpy_Mike, english is not my native language and sadly it´s the plain translation of "armored" in brazilian portuguese the right word, google show me some outputs on http://www.google.com.br/search?hl=pt-BR&source=hp&q=%22armored+cables%22&btnG=Pesquisa+Google&meta=&aq=f&oq=

I was totally fooled by myself :o

I just wanted to acknowledge and thank all of you for your answers. I will certainly take all your advice and try to put it in action and will post here my progress and any further questions. Thank you!! Nahom