Hi, I have a question on how to arrange a series + parallel combination circuit.
I will connect that circuit with arduino later but for now, I want to verify the correct way to arrange a series + parallel combination circuit.
I am thinking to connect 10 LEDs in series and make this series three.
And then, connect those series in parallel.
Please check this picture and tell me whether it is ok.
that can work, but all the led are in parallel, not in serial...
hum, and you will need a way to control the current... at least in form of a resistance...
yes, that's what I was worrying about.
To me, it is also looked parallel. But I need to connect all the LEds in series so that the voltage goes up according to the number of the LEds and current remains.
Your LEDs are all in parallel.
The vertical strings need to be series.
Hi, then, could you show me how to take care of the polarity of the LEDs to make it series? Because, i am totally confussed.
Series just means repeatedly connecting anode-to-cathode, just like batteries in series.
(sorry,no current access to drawing tools and my ASCII art sucks)
A poor analogy would be a stack of coins, with the heads facing the tails, so wherever you cut the stack, the top of the stack has a head, and the bottom of the stack has a tail.
As you've drawn it, all your coins are side-by-side, heads upwards.
(like I said, it isn't a great analogy 
Hi, then is this a right way to make series circuits in a parallel circuit?
That is correct, there should be a resistor in each vertical bar for current limiting and you'll need a decent voltage across them to overcome the forward voltage drop of each led. 10 leds at say 2v each + say 5v to get the current something like correct = 25v between top and bottom. (Its very difficult to get a predictable current if the supply voltage isn't significantly above the total forward voltage of the LEDs)
Hi, How are you?
then, when the LED's maximum forward voltage is 1.7v, the forward current is 100mA and the supply voltage is 5V, should I connect 33ohm like this drawing?
Could you tell me how to chose the wattage of that resistor?
I'm OK thanks 
.You can't feed 10 1.7v LEDs in series from 5 volts (you could try, they wouldn't light up). Realistically you'd need 20 - 25 volts. 100ma sounds like a lot of current for an led (20mA is more usual). If it was 100ma and you used 25 volts for 10 1.7 volt LEDs 25 -17 = 0.1 * X ohms. 8 volts at 100 mA = 80 ohms. The wattage is the voltage drop across the resistor * the current. 8V * 0.1 amps = 0.8 watts. Or 1 watt in obtainable sizes.
If you wanted to use 5 volts, wire them in parallel with 1 resistor for each LED and make sure you've got thickish wire feeding the array and a meaty power supply, they'll use a lot of current.
Thank you very much. I appreciate that.