To illuminate and/or animate your model you need 4 components:

• 1. Source of electrical power;

• 2. Wires to transfer this power;

• 3. Source of light or motion generator; and

• 4. Control components.

First, let’s talk about all of those components and parameters 

Component number 1: Source of electrical power – under this name lies regular battery or (in case of stationary displays) – transformers and AC/DC converters (not musical bands)

Selection of batteries in stores today is quite wide – from micro-miniature batteries for hearing aids apparatus to quite bulky half-brick sized batteries for emergency lighting units. Best suitable for modeling purposes are 9V and/or AA/AAA batteries, because of their compact size and produced voltage.

Parameters to consider during selection process:

• Generated voltage; (measured in Volts)

• Dimensions; (you should store it somewhere, so pay close attention to size of it)

• Stored energy (or capacity, which is measured in Amper*hours or milliAmper*hours – higher number means, you would have more usage from it)

9V batteries are producing 9 Volts, AA or AAA batteries are producing 1.5 Volts, but quite easily could be connected in “chains” to increase Voltage to required level (3, 4.5, 6 Volts).

Battery has 2 contacts or terminals, marked as “+” (positive) and “-“(negative). To increase Voltage you connect + terminal of one battery to a – terminal of other one and resulting element will produce 1.5 + 1.5 = 3 Volts. It’s so simple! (Based, that you are connecting two AA or AAA batteries. For 9V batteries output would be 9+9=18 Volts)

Second component in our list: Wires

There are plenty of different wires out there, but for our purpose we need quite thin INSULATED wire. For American readers – RadioShack has product called “Insulated wrapping wire (30 AWG)” or different colors, for Metric-system countries, please look at your local radio-electronic supplies stores for wire with diameter of 0.25mm.

Having several wires with different insulation color will help. You can use RED wires for Positive (+) and BLACK or WHITE for negative (-). This color identification will help you to avoid mistakes of miss-connecting and thus burning components. 

Next component in our list is actually a visible part, generating this “WOW” from a public: source of light or motion.

In this article I will concentrate on lights only, but same principles applies to motors, too.

Electrical power could be converted to a light using multiple methods, but we would concentrate our attention to 2 of them: incandescent lamp and LED, which is first letters of phrase “Light Emitting Diode”.

Each of them has its own pluses and minuses.

Biggest Plus of LED: it does NOT burn, which makes it probably the best suitable for models – dare to replace bulb, hidden inside of glued wing?

Biggest Pluses of Lamps: they are producing light in wide specter of colors, and to show required one you can use filters, or simply paint lamp in required color. LEDs are generating light of only one wave-length, and you attempt to turn red LED into green by using Tamiya Transparent Green will produce no light….

Another plus of lamp – you can change intensity light, generated by lamp by varying Voltage on it. LEDs are not so easily controlled.

Negative side of lamps: they generate heat! Your model won’t resemble burning stove, but in some cases prolonged usage could damage plastic, so test your installation on piece of sprue from SAME kit (due to variation of plastic parameters being used by different manufacturers or between different models of same manufacturer), to eliminate unpleasant surprise later on.

Parameters to consider during selection process:

• Working Voltage

• Nominal Current

• Size/Shape

• Color (for LEDs)

• Mounting type

- Working Voltage for lamps could be between 1.2 and 12 Volts. For LEDs range is smaller – between 1.2 and 5 Volts. Both of them – Lamp and LED will burn if applied Voltage is exceeding working range. Since LED is a Diode (component, allowing electrical power to flow only in one direction), power to it should be applied accordingly – Positive (+) side of battery should be connected to “ANODE” of LED, and negative (-) side of battery should be connected to “CATODE” of LED.

- Nominal Current is measured in milliAmpers and we will use this number later in our calculations.

- Size/Shape: Smallest lamp I am aware of is “grain of rice” – those lamps are measured 3/32” (2.3 mm) in diameter and 3/16” (4.6 mm) in length. Their working Voltage is 12 Volt and Nominal Current is 30 mA.  Smallest LEDs are much smaller – they are about measured about 1/32” (1 mm), but they are harder to work with because of size. Most popular LEDs are 5 mm (7/32”) and 3.5mm (9/64”) in diameter, but other sizes/shapes are exist and not so hard to find. Plus, LEDs are made of plastic and you can cut, sand and polish them! As long, as you are not touching non-plastic part, you are safe.

- Color should be considered only for LEDs. Following colors are widely available now:

• Green

• Red

• Yellow

• Blue

• While

• Orange

- Mounting type: Most household light bulbs are screw-in type of one of standard size, but when it comes to miniature lights and/or LEDs there is different world. In most cases those components are intended to be soldered to another components or wires, and will have exposed wires or leads for it. Some LEDs (especially miniature ones) do not have any wires or leads – they are designed to be soldered directly to a printed circuit board, and they have contact areas directly on their sides. Those are quite hard to work with, but could be placed almost anywhere, even inside of wing-tip of 1:144-scale model or under cockpit’s instrument panel! 

Last component in our list is called “Control Components”. In most cases it’s a regular ON/OFF switch, but it could be time-delay circuit, which will turn taxi lights On 5 seconds later after navigation lights, or it could apply power sequentially to different engines of C-130 to simulate real-word scenario, when engines are being started one-after-another. Of it could be circuit, controlling flash-blinkers on your plane model. Your own imagination is limit here, not technology. 

If you are intending to “light up” your model, you have to start planning for it BEFORE any assembly steps. All process should be planned up-front.

First, you have to decide what you want to do with this model.

Modern planes got quite a lot of lights in them, so you have to decide what to light-up and what to left out. For example, Boeing 757 has 5 (Five!) separate lights on its front nose gear leg. Most of modern airliners have both – color marker and white flasher lights mounted in wing-tip. Taxi/Landing lights are multi-light units in most cases also.

So you have to make a decision on number and types of lights.

In my opinion lighted model MUST have ALL navigation lights (red/green wingtip, white tail) and flashers, but it’s my personal opinion. For passenger aircrafts it would be nice to light up interior of passenger’s cabin, but it would require actual holes in fuselage to represent windows to be present. Quite a few older kits lack them, presenting windows with decals. Another possibility – lighting up cockpit interior and instrument panel. Taxi/Landing lights, Logo lights (on airliners), Formation lights (of military planes) – possibilities are endless, so be creative… 

So, now, when we are on “same page” with components and you know how many lights you want in your model, let’s start talking about how to do it. 

For sake of this article let’s consider that we are building modern plane and we want following lights to present:

• 1. Port-side red wing-tip navigation light;

• 2. Starboard-side green wing-tip navigation light;

• 3. Tail white navigation light;

• 4. Top and bottom-mounted red blinking lights

This represent minimal external lighting, but it’s quite common to see plane with those lights on. 

This article represents my personal opinion and experience, so I would tell you why I chose what I choose.

Since I did not want any problems with burned lamp later on, I would choose to use LEDs in model. So, first question comes to mind: where batteries should be located: inside of plane or outside of it? If battery is located inside of model, some removable cover should be designed and build, and there is a danger to convert your model into tail-sitter, if battery would be improperly placed or in worst case – plastic undercarriage will break under much heavier load. So, ideal place for batteries – outside of a plane, which will require some base (piece of apron?) and some kind if device to transfer electrical power thru base into model.  This could be accomplished using ground connection cables, connected ground handling equipment, or using wires, hidden in undercarriage. It’s quite important to plan to make all those connections easily re-connectable, otherwise it would be a challenge to transfer model to a competition or just simply replace battery. 

So, let’ plan on our plane.

LEDs are being used as a source of lights,

Batteries located outside of a plane and power would be brought into plane thru connections on MLG (main landing gears).

Looking on internet for a adjustable flashing module, I found product called “Adjustable flasher” on FiberOpticProducts.com (http://www.fiberopticproducts.com/danise/cart.pl?db=stuff.dat&category=Flshadj)

This product allows you to adjust both ON and OFF time of a flash, giving you more control.

This module requires 9V, and this makes a decision of Source of Electrical power quite trivial – 9V battery.

Most LEDs are requiring only 2.5 or even less Volts to be feed to them. If you would give them 9V directly from battery they would burn out, so what should be done to “marry” 9 Volt battery and 2.5 or even less Volt LED?

There 2 at lest 2 solutions to this problem:

First – you can connect LEDs in sequence, like X-mass Tree garland, so each LED will receive allotted amount of power. In this case if something wrong happened with one of component or contact between them you would loose everything, connected to this chain.

Second approach – “eat” extra portion of 9V and feed only required Voltage to LED.

To drop Voltage to required level we would use Resistor. But hot to calculate resistance of this resistor??? Here we would do simple math. But do not worry, it’s very simple! 

The photo at the top of this article is a sample representation of a desired schema: (please forgive me for such a crude drawing). 

Here is a formula: Resistance_in_Ohms = (Power_Supply_Voltage – LED_working_Voltage)/ LED_Nominal_Current. 

So, let’s calculate resistance of resistor which could be used with green LED (considering that our chosen LED would have Working Voltage 2.6 Volts and Nominal Current of 20 mA)

R = (9 – 2.6) / 0.02 = 6.4 / 0.02 = 320 Ohm.

See, we even did not use calculator! It’s so simple! 

For Red LED values could be 3.5 V and 25 mA, but calculations would use same formula:

R = (9-3.5) / 0.025 = 5.5 / 0.025 = 220 Ohm. 

Your calculation may generate some quite un-even number, but for our purpose +/- 10% will work, so do not be shy to round it up to a next whole value, and then you can even round it up to next ten, so 247.85 Ohm could be presented as 250 Ohm.

You can ask me a question: how do I know what is a Working Voltage and Nominal Current for this or those LED? This information is model-specific, and should be available from your retailer or supplier.

Here is one of them with HUGE selection and easy ordering process:

www.digikey.com – they are not only online retailer, there are many-many more, but this company is HUGE and they won’t mind to ship you 1 or 2 LEDs or 200 thousand of them.

You can use brick-and-mortar retailers like RadioShack, but you would pay more. However, at RadioShack you could ask for advice, so there is some pluses and minuses in each case. 

Considering you have all parts (battery, wires, LEDs and resistors) let’s start connecting pieces together! 

LEDs are requiring specific polarity to be connected. Its mean that Positive (+) terminal of battery should be connected to “+” ANODE connector of LED and negative (-) terminal of battery should be connected to a CATODE (-) connector of LED.

In most round-shaped LEDs ANODE (+) connector is longer, but do not take my words on it – check technical documentation of your LED.

Let’s start with port wing-tip red light. Take piece of red wire slightly longer that length of wing and remove insulation from both ends of it. Do not try to expose a lot of wire – ¼ of an inch (6 mm) would be enough. Wrap one end of it around positive (longer) electrode of LED. Take piece of another wire of same length, remove insulation from both ends and wrap one end of it around negative (shorter) “leg” of LED. Make sure, that  LEDs electrodes are not touching each other. Spread those electrodes apart. Take resistor and wrap exposed end of second (not red) wire around one electrode of resistor. Now it’s time to test! Connect red wire to positive (+) terminal of battery and second contact of a resistor to a negative (-) terminal of a battery. Ta-da! You should see bright light coming from LED. If you do not see light from your LED, check all connections and polarity.

Sure, we do not want wires to be just wrapped around each other. You have to master your soldering skills. It’s not hard, but I won’t tell you here how to do it.

To make sure, that you isolate positive from negative you can use heat-shrink tubes.  Take piece of tube of smallest possible diameter which will fit over your soldered contact, cut to length, slide over exposed wire, touch it with tip of your soldering iron and voila – you got perfect insulation wrapped around your wire. 

Repeat same process for each LED, or you can link several LEDs together. To do this you have to connect POSITIVE (ANODE) electrode of one LED to a NEGATIVE (CATHODE) electrode of another one. To calculate required esistor use same formula, but LED_Working_Voltage  should be calculated as a sum of this value fro both LEDs.

Let’s say that we want to connect RED and GREEN LEDs together, and in this case

Working Voltage = 3.5+2.6=6.1V

So, using same formula R = (9-6.1)/0.02 = 2.9/0.02 = 145 Ohm. So simple! 

You can even add third LED to this schema and this will eliminate a need for a resistor!

If you would use 2 RED LEDs and 1 GREEN you will have 2*3.5 + 2.6 = 9.6V, which is in 10% range of 9V, provided by battery. This should work, but you better test-run it before closing your model. 

So, you made several separated “chains” of LEDs, what to do next?

Next, you can connect all of those chains into one piece. Connect all red (Positive) wires together and all Negative wires together, you should gave only 2 points, where electricity from battery should be “fed” to your LEDs. Test it. If some chains light-up, and some not – check connectivity and polarity. 

Next you have to decide where to place LEDs and wires. In some cases it’s impossible to place regular-sized LED to required place. Wing-tip light would be a perfect example of this place. You have 2 choices here

Option 1: use small (and I mean SMALL) LEDs. They are very small – 1*1.5*0.5mm and intended to be mounted directly to a PCB (Printed Circuit Board). So, because of this they do not have electrodes or wires, sticking from them. Instead, contacts are provided on sides of LED itself, requiring some more soldering experience (or luck).

Option 2: place LED anywhere where it would fit, and use FIBER OPTIC CABLE to run light. As wire transfer electricity, FIBER OPTIC CABLE transfers light. FIBER OPTIC CABLE made from special glass or plastic and does not emit light thru its sides. You have to polish both ends of FIBER OPTIC CABLE, attach one end to a LED and you will see light coming from another end. You can bend this cable, tie a knot from it, and light still won’t be interrupted! (As a general rule bent radius of FIBER OPTIC CABLE should be more than 10 diameters of cable itself). 

If you decided to put some of your LEDs inside of fuselage or wing or other parts of your model, you have to paint internals of those parts in black or any other light-masking color, preventing wing from glowing from inside, creating illusion of fire inside of wing.

As alternative solution you can wrap your LED into metal foil. If you decide to place LEDs inside of fuselage, make sure that seems painted with black paint (I used self-adhesive metal foil inside of fuselage to prevent light coming from seams). 

Another important decision to make – how to transfer power from battery, located outside of model to LEDs, located inside of your model. I run wires from wheel wells, like hydraulics lines to bottom of wheel boogies, and put small pieces of square metal tubes to a base, and attaching electrical wires to those metal blocks from under base. Just drill small holes in a base and run wires thru it. This method allows me to lift model from base and put it on any surface without being afraid to break connection of contact. On opposite side – since those metal blocks are glued to base, model could be illuminated only being carefully positioned in one place.

Other possibilities: fuel lines, connected to a plane during refueling, ground power lines, passenger bridge for people hauler or boarding ladders for military planes, etc… 

Sequence of assembling steps could be different, based on model. When I did Boeing 747, fuselage of this model got a “hole” in bottom, which is being covered with special part later in assembly process. This allowed me to assemble wings with LEDs inside and wires sticking out, then glue together fuselage halves, and before putting final cover on fuselage belly I covered all seams inside of fuselage with self-adhesive foil, installed fuselage lights, blinking module, tail light, hooked up all wires (left and right wings, tail light, blinker, fuselage lights) together. Your model may not offer you this kind of access, so be creative, and think about whole process up-front.

Do not worry about LED being buried inside of plastic too deep – just put CA glue on top of it and sand and polish it later. You will have perfectly blended curves.Leo Dashevskiy