The Uno's ports are 5V outputs.
Be aware that the ports with PWM capability can show lower voltages when measured due to using PWM.

Sheers

Please paste the complete code in code tags!

You can find a very good library and tutorials on bildr.org
This can surely help you out.

Cheers

The majority of IC's need a stable powersource to function properly.
This is all dependent on the function and use of the IC.

I would advise you to read a lot about basic electronics and principles.
On the net there are loads of tutorials etc.
This way you can gain knowledge about electronics and recognize the specs that are use in the spec. sheets of IC's.

Unfortunatly there is no shortcut to obtain knowledge :-)

Happy reading...

Check these links :
http://www.arduino.cc/en/Tutorial/ShiftOut
http://bildr.org/2011/08/74hc595-breakout-arduino/

With shift registers you can control a lot of leds without a hassle.
When using the library presented by bildr.org it is also easy to program.

Enjoy!

There is nothing to limit in this case, the led is powered with less than it's forward voltage and will use almost it's nominal current.
You have to check if the current the led uses is not exceeding the current limits of the port it is connected to.

Cheers

Depending on the led's you are going to use and the powersource, this is a feasible project.
I think it is best to use FET's.
Using leds in series you can limit the current use of your powersource and skip the need to use resistors and such.

If you share more details about the project, i and others can provide you with better answers.

Cheers

Please post the complete code in a code block.
This makes it easier to debug for us.

Your secondsPerDelay variable is declared somewhere else so we cannot see how it is declared and where.

Cheers

First you need to check with only a led and a resistor (180/220 Ohm) if the output is turned high.
Have you defined the port at output ?!


If the led is litt like it should, you know your sketch is working.

You need to check if the arduino can deliver the current needed for the relay to switch.
Be aware of the fact that is the voltage to the relais switches to "low", there can be an enormous voltage spike that can ruin you're arduino.
Check on the forum and site how to avoid this by using a decoupling diode with maybe a transistor to switch the relais.

It is always best to deliver the complete code between code block tags!!!

Cheers,

If you want help, you really need to ask the right question.

What is your exact problem, have you tried something?
Did you break you sketches down to small pieces controlling only one piece of hardware?

Did you try something at all?!

If you want help, you need to tell us where the problem lies!!!

Cheers

Just check the other arduino boards and see if one matches your criteria.

he he , how to create a lot of confusion, just ask  ]

No offence 

You do not have to step down the voltage for the arduino to 5V there is a regulator on board.
The Arduino itself has a pin that can provide 50mA at a voltage of 3.3, so no need there as well.

Basically you do not need to step down a lot, check the specs for the servo, they tend to operate at a voltage of 6V.

Btw, using resistors for this purpose is not a good idea because of the power loss in the resistors.

Use voltage regulators instead, they are made for that purpose (78xx series).

Cheers, Peter

This is correct, the arduino can only send packets to nodes on the local subnet.
It has no knowledge of "default gateways" etc. Therefor cannot send packets out of the local subnet.
Basically, the arduino cannot find the "door", it is living oblivious in it's own little world.

Cheers, Peter

Sorry, but you are missing the point.

Whatever you do with apps, phones, routers etc will NOT work unless...
you have a gateway in your lan on the subnet the arduino is on.
There is no way at present an arduino with ethershield can send traffic out into the word by itself because it simply does not know where to send the traffic to.

So,... no it will not work with an Android phone on a different subnet (or out on the internet for that matter).

Cheers, Peter

Just a little addition, because i see it works on the local subnet.

What you can do is send the command to a host on your network and let this host handle the routing and forwarding to the Arduino.
If you do not use a host on the local network then it will be very difficult if not impossible.

Cheers, Peter