Question, how to wire this LED plan?

[DOMENECH1776]

I'm building a small model, that I really want to light, but I've never done lighting before. So I'm not really
sure where to start. I have experience soldering, but no experience with resistors or LEDs.


The diagram has a rough schematic of the model(not to scale and proportions of schematic are off)I have room
for 4 LEDs either 3mm or 5mm. Also I have multiple 1.5 volt batteries that will fit in the model.

http://i222.photobucket.com/albums/dd30 ... 776/Nx.jpg

I'd appreciate any answers, but if someone could point me to a source to learn more on my own that would be great.
Looking for a simple "idiots" guide to LEDs.

These are just questions that I can think of at the moment.

1. If I buy LEDs that work at 1.5 volts with the batteries I already have, do I need a resistor?

2 If I use 2 1.5v batteries stacked, is it still 1.5v output or is it now 3v? 3 batteries = 4.5v?

3. Will a 1.5v LED still emit light at a lower voltage?

I assume that I will have more questions once these are answered, I just don't know what they are yet.

Thank you

[USS Atlantis]

I'm building a small model, that I really want to light, but I've never done lighting before. So I'm not really
sure where to start. I have experience soldering, but no experience with resistors or LEDs.


The diagram has a rough schematic of the model(not to scale and proportions of schematic are off)I have room
for 4 LEDs either 3mm or 5mm. Also I have multiple 1.5 volt batteries that will fit in the model.

http://i222.photobucket.com/albums/dd30 ... 776/Nx.jpg

I'd appreciate any answers, but if someone could point me to a source to learn more on my own that would be great.
Looking for a simple "idiots" guide to LEDs.

These are just questions that I can think of at the moment.

Let's look at these one at a time

1. If I buy LEDs that work at 1.5 volts with the batteries I already have, do I need a resistor?

No, so long as the supplied power does not exceed the LED voltage, no resistor is needed

2 If I use 2 1.5v batteries stacked, is it still 1.5v output or is it now 3v? 3 batteries = 4.5v?

Stacking watch style batteries can be either - looking at the battery, you have the outer disk wrapping slightly over a smaller disk - if you stack them LsLs you're adding voltage, so yes, that would now be 3 volts - if you stack them LssLLs, then you're adding current, so the voltage would remain 1.5, but your light will last longer as the circuit has more current (life) available

3. Will a 1.5v LED still emit light at a lower voltage?

So long as the voltage doesn't drop below the threshold - which is variable based on the LED, then yes - it might be quite dim depending on how much lower the voltage is than the normal, but it will light up

Why not use AAA batteries instead - the available current in a watch battery may light this setup for maybe a few hours or so, where as a pair of 2000ma AAA's (standard for current rechargeable batteries) running 4 LED's rated at 3v will last 33+ hours

Or plug it into a wall-wart and they'll never fade out

I assume that I will have more questions once these are answered, I just don't know what they are yet.

Thank you

You're welcome

Atlantis

[en'til Zog]

Hi, DOMENECH1776.

First, what color do you want LED 1 to be? If it's lighting portholes do you want YELLOW light or WHITE? Using an LED that produces the color you want, without having to put a filter on the LED, is the most efficient way to get the color you want. WHITE LEDs typically need 3.6 volts or thereabouts to operate properly. A slightly lower voltage will give slightly less light, but longer life for the LED. YELLOW LEDs typically need less voltage - 1.9 to 2.8 depending on the specific LED.

The other three are apparently RED ones, which should run at from 1.8 to 2.8 volts each, typically. The very bright LED-94 LEDs from All electronics ( www.allelectronics.com ) need only 1.8 volts to reach full power, at 0.020 amps ( 20 milliAmps ).

If you want a WHITE LED and 3 RED LEDs in your model, you could use 3@ AA or AAA batteries in SERIES, and separate resistors for each LED. Or you could use a 4.5 volt REGULATED DC "wall wart" or power supply and a separate resistor for each LED.

Have you read all the ANNOUNCEMENTS in this forum? There's a lot of information there.

HTH

[DOMENECH1776]

SCC-7107 USS Atlantis

For your answer to question 2, does the following diagram match your answer?

http://i222.photobucket.com/albums/dd30 ... teries.jpg

As for the AAA batteries, they won't fit in the model. Yeah, it's gonna be small. One of these will go to a friend, who will want to hang it, so I can't use a wall-wart, at least not without it ruining the effect.

en'til Zog

LED 1 was a toss up, but I'm thinking of going to yellow now. The other three were going to be white, with a transparent red plastic for the light effect. But maybe I'll go with red LEDs and use a white transparent plastic for the impulse drives and bussard collectors, They are usually a white gray, when powered down anyway, IIRC.

If I use the yellow and red LEDs, the voltage requirement will be lower.

I have read the announcements and searched throught this forum, but I didn't see an answer to the battery question. And I tend to get lost with a lot of the technical terms, so even if the answer was there, I could have read it, and just not understood it.

Thanks to you both, I'm about 2 weeks away from trying this out. I'll keep you posted.

Chris

[USS Atlantis]

SCC-7107 USS Atlantis

For your answer to question 2, does the following diagram match your answer?

http://i222.photobucket.com/albums/dd30 ... teries.jpg

Exactly right, and the text is correct as well. Probably want to go for three in the stack to make it easier to access both Positive and Negative. When stacking batteries in Parallel (right hand diagram) standard is to use odd numbers of batteries, in Series (left hand diagram) any number is possible.

As for the AAA batteries, they won't fit in the model. Yeah, it's gonna be small. One of these will go to a friend, who will want to hang it, so I can't use a wall-wart, at least not without it ruining the effect.

en'til Zog

LED 1 was a toss up, but I'm thinking of going to yellow now. The other three were going to be white, with a transparent red plastic for the light effect. But maybe I'll go with red LEDs and use a white transparent plastic for the impulse drives and bussard collectors, They are usually a white gray, when powered down anyway, IIRC.

If I use the yellow and red LEDs, the voltage requirement will be lower.

I have read the announcements and searched throught this forum, but I didn't see an answer to the battery question. And I tend to get lost with a lot of the technical terms, so even if the answer was there, I could have read it, and just not understood it.

Thanks to you both, I'm about 2 weeks away from trying this out. I'll keep you posted.

Chris

Ya, yellow is probably your best bet, for whites, you'd need 3 volts normally and the 1.5 would probably drop the intensity a little too much.

Reds and Yellows are good choices for a limited voltage setup like this one - though if you went with a 3v stack, you'd need a resistor for the reds to prevent burn-out.

Atlantis

[Sparky]

Where have you seen 2 Amp AAA rechargeables? 2000mA is 2 amps. I had some 2 volt 2 amp-Hour cells they where ruffly %20 larger than a D battery.

[USS Atlantis]

Where have you seen 2 Amp AAA rechargeables? 2000mA is 2 amps. I had some 2 volt 2 amp-Hour cells they where ruffly %20 larger than a D battery.

Sorry, the AAA's run 750-1200 ma capacity - depending on the brand

I was thinking my AA's, which are 2000ma; though you can find some that have up to 2600ma capacity

Energizer and Duracell have AAA's in the 750-800ma range; AA's in the 2000-2400ma range - available at any big-box retailer (Target, Wally-World, etc)

And yes, these are all NiMH rechargables

Atlantis

[Mr. Engineer]

Can I post a suggestion here?

Anyway, I am not sure how "small" is small but when it comes to using watch batteries, they tend to drain off pretty quickly. So, if you need to display it lighted up most of the time, maybe a wall adaptor would be a better idea, IMHO.

The model looked like the first Warp ship by Zephram Cochrane (in Star Trek: First Contact), right?

[DOMENECH1776]

The model won't be lighted all the time. And the "small" is small. So for batteries, watch batteries will have to do.

No, it's not the Phoenix, but more in line with the warp 2 project ship, but carried a few decades later.