Question about led's

[kahless78]

I hope this doesnt sound stupid but I have no experience wiring led's so here is my question?

Can i wire a bunch of White 3.3vdc 8000 mcd 5mm led's say 30 of them mixed with a couple of blue and red ones. Each light will have a resistor of
200 Ohm . Can all of this work off of a single 9 volt battery?

[USS Atlantis]

I hope this doesnt sound stupid but I have no experience wiring led's so here is my question?

Can i wire a bunch of White 3.3vdc 8000 mcd 5mm led's say 30 of them mixed with a couple of blue and red ones. Each light will have a resistor of
200 Ohm . Can all of this work off of a single 9 volt battery?

Ok - LED-101

1) Yes, you can mix colors so long as you have the correct resistor attached to each one

2) Need to know the current rating of the LED as well as the voltage - normally will be listed as ??ma

3) To calculate the correct resistor for the LED - (Vs-Vd)/A

Vs - is the source voltage - you've stated this as 9v
Vd - is the LED voltage drop - again, stated as 3.3v
A - is the current rating of the LED - unstated, but I'll use 20ma or .02A (that's what the LED's I get are rated at)

So - (9-3.3)/.02 = 285

So you should have at LEAST 285 Ohm resistors for the Whites

Blues are normally the same as Whites - so use the same rating

Reds are normally in the 1.8v-2.2v range - so recalculating

(9-2.2)/.02 = 340 Ohms

So you'd need at LEAST a 340 ohm resistor for each Red

Now - notice I said "at least" - NEVER use a resistor less than the calculations state - sometimes the calcs will designate a value that's non-standard

Get the next HIGHER rating in a standard value - all this will do is dim the light output a little bit

Going to a resistor LESS than the calculated value has a chance of having your LED blow - no light

Hope this primer helps a bit

[kahless78]

Ok I get it thanks man but how many of those led's can I power off of a 9 volt battery 100? is there a exact number?

[USS Atlantis]

Ok I get it thanks man but how many of those led's can I power off of a 9 volt battery 100? is there a exact number?

Actually, it's not the Voltage, but the Current that matters

9 volt batteries are notorious for having low capacity - 120-1200maH (milli-amp hours)

Basically - if you hook up 10 standard LEDs that rate 20ma each - you'll get from 1-10 hours of light

Add to that, all those resistors cutting the voltage down by 2/3 to 3/4 will also generate heat

Personally - if you're going to go with batteries, I'd suggest a 3volt system - a pair of AA's

1) Current NiMH rechargeable batteries hold 2300-2700maH - twice or more what a 9V holds

2) Using the lower voltage source will require smaller value resistors, generating less heat

With 100 LED's, you're pulling 2000ma - so the 9v will last between 3 and 36 MINUTES - the AA's will last 61-81 minutes

Still not a great deal of time

Better yet - get a plug-in AC/DC adapter (like the charger for your Cell-phone/Palm/whatever) - make sure it's a REGULATED output, then so long as you got an outlet nearby, you got light

Again, with 100 LED's, your pulling 2000ma (2 amps), so get a wall-wart (that's what we call them) capable of handling your needs

[kahless78]

Ok so here is another question I am sorry about all of them lol

Where do I get a regulated plug-in AC/DC adapter? do they come as a kit with the connectors? Do i just wire it up negitive wire to negative wire positive wire to positive? How many led's can I run off of the adapter say 200?
I greatly appreciate the help guys sorry for being a noob.

[Ziz]

How many LEDs goes back to the issue of milliamps. Add up the amperage of your LEDs and make sure the power supply is rated for equal or more than that amount.

Look at it like a water pipe.

Voltage = the diameter of the pipe = how much water can go through it.
Amperage = the pressure of the water = how fast the water can go through.
Current = the drain = how fast the water empties from the sink after it comes out of the pipe.

So, just like you can never fill a sink with a huge drain using a drinking water fountain, if the current your LEDs pull (voltage x amperage) is higher than what the power supply can give it, eventually your power supply will burn out, be it batteries or wall adapter.

In the end, "how many LEDs" is a relative question. If you want to add more LEDs, do the current math and get a bigger power supply to match it.

[kahless78]

Ok I think I understand now but let me tell you what I am doing so that way you guys understand

I am building a pl 1/350 refit and I want to light it.
I need a total of 62 led's to do this.

58- 5mm white 20ma 3.3 vdc led's
2- 5mm red 20ma 2.3 vdc led's
2- 5mm blue 20ma 3.1 vdc led's

I am looking for a wall wart thats rated at 1240 ma or above like the 2000ma ones correct?
So now I need to know how many volts the power supply is then I can see what kind of resistors to buy correct?

Once I have that figured out all I have to do is wire everything up and bingo we have lights.

Now here is another question I want to be able to turn on different parts of the lights using multiple switches example would be to have the window lights on then be able to turn on the deflector and spot/running lights when ever I wanted. So do I need multiple power sources or can this be done with a single?

[kahless78]

So my next question will be this I found a 12v 2000ma ac/dc regulated adapter but where do I get the part that i wire the lights too? I have no idea what it is called and I think I will need a least a 300 ohm resistor on each led. lol This is so confusing I think I almost got it but I am not sure I have wireing and soddering skills so I think i can do this I jus need you experts out there to help me lol

[USS Atlantis]

Ok I think I understand now but let me tell you what I am doing so that way you guys understand

I am building a pl 1/350 refit and I want to light it.
I need a total of 62 led's to do this.

58- 5mm white 20ma 3.3 vdc led's
2- 5mm red 20ma 2.3 vdc led's
2- 5mm blue 20ma 3.1 vdc led's

I am looking for a wall wart thats rated at 1240 ma or above like the 2000ma ones correct?

Correct - I'd go for a 1.5a or 2a (1500ma or 2000ma) just to have a little to spare

So now I need to know how many volts the power supply is then I can see what kind of resistors to buy correct?

Again, correct - I'd go with a 4.5v or 6v, and make sure the supply is regulated; un-regulated supplies can have a variation in the voltage that could be hazardous to your LEDs

Once I have that figured out all I have to do is wire everything up and bingo we have lights.

Now here is another question I want to be able to turn on different parts of the lights using multiple switches example would be to have the window lights on then be able to turn on the deflector and spot/running lights when ever I wanted. So do I need multiple power sources or can this be done with a single?

Nope, just a single supply can do it

Imagine a shower - starts out as a single run (the supply pipe) but at the head, it gets split apart into separate streams.

You can run multiple wires from the power supply, one going to each LED/resistor combo - between the power supply and the LED/resistor, you can put in a switch or even a small circuit that controls the LED (blinky lights are common to SF Modelers)

Then all those lines come back together to the ground of the Power supply (streams join up to go down the drain)

[USS Atlantis]

So my next question will be this I found a 12v 2000ma ac/dc regulated adapter but where do I get the part that i wire the lights too? I have no idea what it is called and I think I will need a least a 300 ohm resistor on each led. lol This is so confusing I think I almost got it but I am not sure I have wireing and soddering skills so I think i can do this I jus need you experts out there to help me lol

If it has a plug on the end, you need the correct socket

Most parts can be gotten at Jameco, Digi-Key or {wince) Your local Radio Shack

And my calculations show that you need 435 ohm resistors for the Whites, 445 for the Blues and 485 for the Reds

BUT - you can put LED's in series

SO from a 12v supply

White - White - White - 105 Ohm resistor
Blue - Blue - 135 Ohm resistor
Red - Red - 370 Ohm resistor

So your two blues can link together and so can your two reds

Better still - since the ma rating is the same

Blue - Blue - Red - Red - 65 Ohm resistor

So in summary, you can link up 3 White LED's in a line and use a smaller resistor - helps with that heat build-up problem mentioned earlier

AND you can connect your Blues and Reds together

This has the effect of using smaller value resistors, less individual wire runs and everything can still be run off the single 12v power supply

[kahless78]

ok kool thank you so much. So one last question. I can hook up all white led lets say for my windows add a switch and they will be able to be turned on and off.

for my deflector and impulse crystal i go from the power wire that has all the other lights wired too to that with different switches to another switch, then to the blue leds then to the red ones for my impulse engines then to the ground having all the right resistors in place so that way I can have my deflector and impulse engines turn on at a single switch. just like how I want to do the lights on the windows and spot/running lights So in short just get what you said then have fun wireing everything up lol as long I have the right resistors and I havent went over my power supply I am good to go? So in short use the resistors you told me for the blues and reds and whites and thats it Also and this is where i am confused how do you wire the leds to the socket the power suppy connects to? do they have a positive and a negative wire?

[USS Atlantis]

ok kool thank you so much So one last question I can hook up all white led lets say for my windows add a switch and they will be able to be turned on and off.

for my deflector and impulse crystal i go from the power wire that has all the other lights wired too to that with different switches. to the blue leds then to the red ones for my impulse engines then to a switch then to the ground having all the right resistors in place so that way I can have my deflector and impulse engines turn on at a single switch. just like how I want to do the lights on the windows and spot/running lights So in short just get what you said then have fun wireing everything up lol as long I have the right resistors and I havent went over my power supply I am good to go? So in short use the resistors you told me for the blues and reds and whites and thats it

Here's a little ASCII diagram for the Blues & Reds

12vps (+) > switch > +blue- > +blue- > +red- > +red- > 65 Ohm Resistor > 12vps (-)

So, in talk - start at the Positive Side of the Power Supply, wire to one side of the switch, other side of the switch goes into the Anode of the first LED, Cathode of #1 to Anode of #2, Cathode of #2 to Anode of #3, Cathode of #3 to Anode of #4, Cathode of #4 to resistor, resistor to the Negative Side of the Power Supply

NOTE: make sure you know the Anode from the Cathode on the LEDs - wire them backwards and you'll have anything from non-working to blown

For the Whites

12vps (+) > switch > +white- > +white- > +white- > 105 Ohm Resistor > 12vps (-)

Repeat as needed to wire up all the LED's

The switch is optional, you can have it to control the lights or leave out to have the lights on all the time

[kahless78]

So I dont need to wire each led with a resistor then? So on one section All i need to do is to go from the power wire to a switch to the led anode to led cathode then the next one will go back to the anode then to the cathode so on and so until i have 30 of them together or how ever i need then add the resistor then to the ground? So i dont need a whole lot of resistors then just enough for each section of lights. I will not be mixing any colors so i think thats what u r tellin me lol oh and the anode is the positive longer wire and the cathode is the negetive shorter wire . If that is right I am ready to start this build lol god I hope so Tis has been rackin my brain now for hours tryin to figure it all out lol

[USS Atlantis]

So I dont need to wire each led with a resistor then? So on one section All i need to do is to go from the power wire to a switchto the led negetive to positive to led to led so on and so until i have 30 of them together or how ever i need then add the resistor then to the ground? So i dont need a whole lot of resistors then jus enough for each section of lights. I will not be mixing any colors so i think thats what u r tellin me lol

No, can't do 30

Simple calculation

LED's in series (hooked up plus-to-minus) add voltage requirements
LED's in parallel (individual runs of wire) add current requirements

30 White LED's in series would require 30*3.3 = 99 volts

Using a 12v power supply, the most you can hook up in series is 3 (9.9v (4 LEDS would need 4*3.3 = 13.2v - more than the 12v the PS can handle))

So for the 58 Whites - your best best is 18 runs of 3 LEDs each then 2 runs of 2 LEDs each

So you'll need 1 each of the 65 Ohm resistor (for the blue-blue-red-red run), 18 each of the 105 Ohm resistors (for the 3 White LED runs) and 2 each of 270 Ohm resistors (for 2 White LED runs (PS+ > +white- > +white- > 270 Ohm resistor > PS-))

[kahless78]

≠♀§#&@(§ LOL ok here we go let me see how this works

Ok 12 volt power supply i need to run at least 35 white leds for the windows in both the saucer and the secondary hull so on this strand i will go from the power supply to switch to a 105 Ohm resistor then to led then repeat this untill I have all 35 together each with a resistor then to the ground.

next strinng will be for the spot lights that will need 22 white leds
12 volt power supply to a switch then to a 105 Ohm resistor then to the led then repeat this until I have all 22 each with a resistor together then to the ground

next will be the defector dish deflector crystal and impulse engines. this will need 4 led 2 blue 2 red
12 volt power supply to switch then to 65 Ohm resistor to led repeat util all 4 are together with resistors then to the ground

shutle bay

5 white leds do this the same way i did on the other white strands?

God I need a dam diagram lol

[USS Atlantis]

≠♀§#&@(§ LOL ok here we go let me see how this works

Ok 12 volt power supply i need to run at least 35 white leds for the windows in both the saucer and the secondary hull so on this strand i will go from the power supply to switch to a 105 Ohm resistor then to led then repeat this untill I have all 35 together then to the ground.

next strinng will be for the spot lights that will need 22 white leds
12 volt power supply to a switch then to a 65 Ohm resistor then to the led then repeat this until I have all twenty each with a resistor together then to the ground

next will be the defector dish deflector crystal and impulse engines. this will need 4 led 2 blue 2 red
12 volt power supply to switch then to 65 Ohm resistor to led repeat util all 4 are together with resistors then to the ground

shutle bay

5 white leds do this the same way i did on the other white strands?

Not quite - let me try again

For 12 volts, the max number of White LED's in a single string is 3 - so

Power supply to switch to White LED to White LED to White LED to 105 Ohm resistor to ground

Now, if you get a switch that can handle 250ma of current, then you can hook up the 12 individual runs off the one switch

Actually, let me run up a schematic and post a link, maybe a picture is better - give me about 20 minutes

[kahless78]

I really appreciate this bud thank you so much my past build of his model i just used battery powered led light strips that i placed in the hull. I want to go all out but cant afford trek moddelers light kits.

Part of the reason I am so confused is because i want to do a build like this guy I think his name is Raytheon and on his model he uses two switches and the thing works I would need twenty switches and ALOT of wires that i couldnt fit in the hull if I did it the way i think you are telling me

[USS Atlantis]

Ok

For one - Ian (Raytheon) is considered one of the guru's of ST Lighting - it's a good goal to shoot for, but even I'm not ready to challenge Ian in the lighting arena

Two - got a basic schematic worked up

http://i287.photobucket.com/albums/ll13 ... n/LEDs.jpg

We can't post inline images here, so you'll have to refer to the image as I describe it

From the Power supply (J1) you can either run through a the switch (S1) or directly to the first LED in a string

Each string has a maximum of 3 White LEDs (LED 1-3, LED 4-6, LED 7-9)

Each string ends with a single resistor (R1, R2, R3)

From the resistor, you connect back to J1 Ground, completing the loop

You can have as many strings as you have power - running this way, your 58 White LED's would be on 20 strings - so 20*20ma = 400ma or 0.4a

So you can get by with a smaller power supply by running them in series-groups

You can also add more switches if you want separate controls for different groups of lights - Just add another switch in parallel to S1 and run the other strings of 3 off the second switch (or third or fourth)

[kahless78]

ok i understand now

for the white leds

from the power source i have a positive and a negetive.
using one switch I can connect as many strings as I want. but they can only be 3 lights in a string. After I connect positive to negetive, positive to negetive, positive to negetive I then will put a 105 ohm resistor to the negetive wire that goes back into the power supply. I do this and basically branch them off the same main power wire unti I have the desired number of lights needed for the hull.

now on to the spot lights since they are white I will use the same main power wire and basicaly repeat what I did the first time.

next the deflector and impluse i will use the main power wire again with switch but go blue led blue led red led 65ohm resistor then back to ground on supply

while using the same power and ground wire for each string just branching it off like a tree but dont excede more than 3 lights per branch so to speak.

So just keep track of what you are doind and your good to go? could I still use a 2000ma power supply?

[USS Atlantis]

Yep

Always check the calcs for the Resistor

(Vs-Vd)/A

For the 3 Whites, the calc is (12-(3.3+3.3+3.3))/.02 or (12-9.9)/.02 = 105

For the Blue-Blue-Red-Red (12-(3.1+3.1+2.3+2.3))/.02 or (12-10.8)/.02 = 60

For your strings of 2 Whites (12-(3.3+3.3))/.02 or (12-6.6)/.02 = 270

To calc the total ma needed add up the number of strings

You can use the 2000ma supply, unused power just sits there, it doesn't do anything - and using a supply with more than enough capacity also lets it run cooler, extending it's life

[kahless78]

sweet I get it now I hope lol just need to make a really long power and ground wire lol. so my final question for you my friend is this. I promise that this is the last one

Using 63 led I will have a total 21 strings all running off the power wire and conecting to the ground wire on the 12 volt supply. I beleive that I am still under the 2000ma on the power supply so a 12volt 2000ma supply will work?

[USS Atlantis]

sweet I get it now I hope lol just need to make a really long power and ground wire lol. so my final question for you my friend is this. I promise that this is the last one

Using 63 led I will have a total 21 strings all running off the power wire and conecting to the ground wire on the 12 volt supply. I beleive that I am still under the 2000ma on the power supply so a 12volt 2000ma supply will work?

21 strings @ 20ma per string is 420ma - about 1/5 the rating of the power supply

Even if all 63 LED's were hooked up individually - 63 strings of 1 LED each - you'd be safe - 63*20= 1260ma or 63% of the rating

[kahless78]

wow thank you so much you taught me how to use and wire leds over night now I am sure I can wire up my own light kit and make it work with different switches the way I want it to lol now about what type of wires to use lol

[USS Atlantis]

wow thank you so much you taught me how to use and wire leds over night now I am sure I can wire up my own light kit and make it work with different switches the way I want it to lol now about what type of wires to use lol

For all my wiring, I use Wire-Wrap - it's 30 gauge, solid, insulated - will handle 500ma current - since your setup runs at 420ma - you're safe using thing

Jameco has some here, $7 for a 100' spool

[macfrank]

The LED series/parallel array wizard is probably one of the easiest ways to calculate the resistors and current required to drive an array, with any source voltage.

[kahless78]

ok so after figuring out how many led's I need i came up with this number

I need 51 led's total
48 white 5 mm 3.3 at 20ma
2 blue 5mm 3.1 at 20 ma
1 red 5mm 2.3 at 20 ma

now I have a total 16 strings I will be running off of a 12 volt power supply my power supply will be a 2000ma one

for each string of 3 white leds i will need a resistor of 120 ohms
for the blue - blue - red led combo I will need a resistor of 180 ohms

I used the calculator and this is what it gave me

[USS Atlantis]

ok so after figuring out how many led's I need i came up with this number

I need 51 led's total
48 white 5 mm 3.3 at 20ma
2 blue 5mm 3.1 at 20 ma
1 red 5mm 2.3 at 20 ma

now I have a total 16 strings I will be running off of a 12 volt power supply my power supply will be a 2000ma one

for each string of 3 white leds i will need a resistor of 120 ohms
for the blue - blue - red led combo I will need a resistor of 180 ohms

I used the calculator and this is what it gave me

And using my old fashioned method - ya, I have that site linked too, but I always believe in a backup (I have a slide ruler to back up my digital calculator)

Looks right to me - and you upped the ohms rating to the next standard size - which is correct

Don't forget to post pics of your progress someplace and link to it to keep us updated (posting pics directly here is a no-no)

[kahless78]

kool I am 100% confident I can do this thanks for all your help guys