# wiring sequence leds

#### mick97

Jul 31, 2011
10
Hi,

Im kinda new to this so bear with me please
My question is as follows.

I want to put a series of leds together. 50 of them to be exact.
Only one will be on at a time,and they will be connected to a button(switch) for foreward,and backwards.
So what would the process be.
Solder them all together end for end,and then the first one and the last one will go to a battery?
Wondering if I would need 2 double AAs ?
They will probably be 2mm diffused im thinking so far.
Would i also need a current limiting resistor?

I know red color runs about 1.8 to 2 volts.
I will also have a blinking light at the end of the string,and a really small speaker that makes a sound..not sure of the speaker rating on voltage as i haven't been that far yet.

Any feedback would be appreciated.
Thanks,
Scotty

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
You should first read this. Then come back with other questions.

#### mick97

Jul 31, 2011
10
Ok so i need resistors for each one.Alot of work lol...

If I bought a led strip(all connected in series already) what would i need to only make one light up at a time through the switch i use to go foreward and backwards?
The strips all light at once,so i need something that goes in between the switch and lights i would guess,, so only one light would spark each time i hit my button.
Scotty

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Presuming you have sufficient voltage, you can place a number of them in series with a single resistor.

For 50 LEDs and a battery (with sufficiently high voltage) you can wire up (say) 10 strings of 5 LEDs -- with each string having a resistor (thus 10 LEDs). For red LEDs, you would probably require 18 volts or more to do this -- preferably somewhat higher.

With 2 AA cells, and excluding your use of some magic (boost SMPS) the best you can do is 50 individual LEDs, and yes, preferably each with their own resistor.

#### mick97

Jul 31, 2011
10
Ok I used the chart page i found and it looks like every 6 leds i need a resistor.Thays kinda a kewl tool
only one light will be lit at a time,so a AA will not be enough you think?

I wasnt sure of the voltage source so i put 12.
That may be wrong as 2 AAs use 1.5 volt x 2 = 3 volt.

Ok i just did 3 volt and it shows a resistor per led,so yup your correct for resistor each.Alot of work lol
Im not sure if i can get a series or strip leds to squeeze into the little space i have,but am looking into it.

#### mick97

Jul 31, 2011
10
Does this wiring diagram look correct?
I went through the steps below to come up with this..............

Just put in these numbers I have below into the chart,and this is what I get...

Source voltage (3) Using 2 AA batteries,as 2 AA equals 3w as they are 1.5 a piece...
diode forward voltage(2.0)
diode forward current (mA) (20) as Im doing this one for RED diode.
number of LEDs in your array.. 120 led's im using.
I used this chart (( http://led.linear1.org/led.wiz ))

R = 56 ohms
So 56 ohm or 1/2 w would work.
The color code being (((Green-Blue-Black )) 560

Not sure if 2 AA batteries is what I need but guessing so as it is going to only run (1) light at a time,so not alot of power here.

==============================================================
Any ideas on this would be appreciated as far as the 2 AA.
Mabe it would need 3 AAs.
Scotty

#### mick97

Jul 31, 2011
10
Does this wiring diagram look correct?
I went through the steps below to come up with this..............

Just put in these numbers I have below into the chart,and this is what I get...

Source voltage (3) Using 2 AA batteries,as 2 AA equals 3w as they are 1.5 a piece...
diode forward voltage(2.0)
diode forward current (mA) (20) as Im doing this one for RED diode.
number of LEDs in your array.. 120 led's im using.
I used this chart (( http://led.linear1.org/led.wiz ))

R = 56 ohms
So 56 ohm or 1/2 w would work.oops,I mean 1/4 w.
The color code being (((Green-Blue-Black )) 560

Not sure if 2 AA batteries is what I need but guessing so as it is going to only run (1) light at a time,so not alot of power here.

==============================================================
Any ideas on this would be appreciated as far as the 2 AA.
Mabe it would need 3 AAs.
Scotty
--------------------------------------------------------

#### TBennettcc

Dec 4, 2010
292
If you only want one LED lit at a time, that "chart" page will not do it. You will definitely need some control circuitry, possibly one or more microcontrollers.

If you wired that diagram, with all of the LEDs on at the same time, it's telling you the array will draw 2400mA. Standard AA's are about 2700mAh, which means they will sustain a current draw of 2700mA for about an hour before completely dying. Keep in mind the voltage of the AA's will drop as the energy stored in them is depleted. This means the current through your LEDs will decrease as well, as Ohm's Law says V = I x R, or V / R = I. This shows that if the voltage drops while the resistance remains the same, the current will also fall.

#### mick97

Jul 31, 2011
10
Any ideas on how to do that Tim?
The tools online only go so far I guess.lol
Scotty

Replies
2
Views
123
Replies
5
Views
154
Replies
13
Views
202
Replies
1
Views
163
Replies
4
Views
199