| NF-3RC extends the capabilities of the NF-2RC unit with a greater number of circuits and more flash lights regimes. Just as NF-2RC it has two position lights circuits. It has also two landing lights circuits and two flash light circuits. Switching on/off of the second landing lights circuit is delayed by 1 second against he first circuit. That produces an effect of phased switching by the pilot. Eight different combinations of flashing can be selected for the two flash light circuits. Three couplers (jumpers) are used for selection.
The customer can propose possible combinations and try them using a program simulator and ask them when ordering. The program simulator is available on the Web.
One second is split into 16 parts. It is possible to set during which parts the light should be on (1) and off (0) to both flash circuits. Such a couple of sequences of 16 ones and zeros represents one combination of flashes. Eight such combinations (couples of sequences) are saved in the unit. By default, the unit contains six combinations of 1, 2 and three mutually shifted flashes plus two flashing modes 1:1, one with the period 1s, the other twice faster. The last two regimes are designed especially for helicopters owners.
A coupler is used for selection of 2- and 3-positional control regime as in NF-2RC. If the 2-position control is selected, in the first position the position and ant-collision lights light, in the second position the landing lights get switched on, too. In the three-position regime, in the first position, all lights are off, in the second position the position lights and anti-collision flash lights are on and in the third position, all lights are on. The unit can be used also in no-control mode. In that mode, position and flash lights are permanently turned on and the coupler for regime selection switches the landing lights.
Thanks to a galvanic separation of the receiver’s and power circuits (by an opto-member), the illumination can be powered both from a common source or from an independent accumulator. The NF-3RC unit can be used also as a basis for your own constructions for excitation of MOSFET power transistors.
The circuit is extended with detection of failure of the receiver's signal - it is indicated by permanent flashing of the anti-collision flash lights and the landing lights.
NF-3X (eXtra) compared with the NF-3RC has a strengthened second landing lights circuit so that it can power reflectors with 350 mA or 500 mA. LED Luxeon models and/or crypton bulbs can be used.
NF-3XL (eXtra Large) has, unlike NF-3RC, all position and flashing circuits strengthened for supplying 150mA LED diodes and for the landing reflectors circuits of 350mA. Moreover, it has an extra illumination circuit of 20mA for cabin illumination or for background illumination of board instruments. The circuit is switched on together with position lights.
Units compared:
|
type |
P1 |
P2 |
F1 |
F2 |
L1 |
L2 |
I1 |
flashes |
control |
dimensions/ weighth |
|
|
mA |
mA |
mA |
mA |
mA |
mA |
mA |
|
|
mm / g |
|
NF-1 |
20 |
20 |
20 |
|
|
|
|
1x |
|
45 x 24 x 5 / 4,7 |
|
NF-1RC |
20 |
20 |
20 |
|
20 |
|
|
1x |
2p |
45 x 24 x 7 / 7,2 |
|
NF-2RC |
20 |
20 |
20 |
|
20 |
|
|
1x, 2x, 3x |
2p/3p |
55 x 24 x 6 / 8,0 |
|
NF-2m |
5 |
5 |
5 |
|
5 |
5 |
|
1x, 2x, 3x |
2p/3p |
32 x 15 x 6 / 2,3 |
|
NF-3RC |
20 |
20 |
20 |
20 |
20 |
20 |
|
8 variants |
2p/3p |
55 x 24 x 6 / 8,6 |
|
NF-3X-150 |
20 |
20 |
20 |
20 |
20 |
150 |
|
8 variants |
2p/3p |
72 x 24 x12 / 13,0 |
|
NF-3X-350 |
20 |
20 |
20 |
20 |
20 |
350 |
|
8 variants |
2p/3p |
72 x 24 x19 / 13,7 |
|
NF-3XL* |
150 |
150 |
350 |
350 |
350 |
350 |
20 |
8 variants |
2p/3p |
75 x 52 x19 / 36,2 |
explanations: Voltage units range:
P1,P2 = Pos = running lights NF-1 and NF-2 line : 6 - 14 V, typically 9 V.
F1,F2 = Flash = flashing lights NF-2m type: 4,5 - 5,5 V , typically 5V
L1,L2 = Land = landing lights NF-3 line: 5,5 - 14 V, typically 9 V.
I1 = Inter = cabin lights Voltage of receiver’s circuits 4,5 - 5,5 V (all lines).
2p : a 2-position switch selects: 1st pos = P+F; 2nd pos. = P+F+L.
3p : a 3-position switch selects: 1st p. = off, 2nd p. = P+F; 3rd p = P+F+L
2p/3p : 2p or 3p regime can be selected with a coupler.
Model illumination for flying at night:
Recently, a new hobby has emerged among aircraft modelers: flying at night. Sometimes it is a new part of night program at modeler's competions, sometimes a modeler gets attracted to it by the desire of new experiences. Who has once tried it will agree that the experience is worth it. I became personally enchanted by night flying myself.
There are different solutions of aircraft illumination available: some based on chemical cold light (sticks), others based on miniature bulbs and others based on ultra brights LED diodes. The chemical sticks are designed for one-time use, but you have just to activate them, attch them and fly. This is an ideal solution for a one-time show that does not require change in the aircraft's construction. But it is more model-realistic to use bulbs or LEDs.
The advantage of small bulbs is in their price and availability. They are available for different voltages and power and you can probably find bulbs that can be attached to accumulators directly. However, one must expect power consumption in the degrees of tens and hundreds of mA. Thus the domain of bulbs is among the big models that do not lack greater accumulator capacity. The light of bulbs is more or less omnidirectional. The model is visible in any position. If bulbs are used as position lights where by deafult green (left) and red(right) color lights are used, it is necessary to color the bulbs or color them. It must be anticipated that it results in reduction of light intensity of the bulbs.
For illumination of smaller and slower models, ultra bright LED diodes are sufficient. Their advantage is a low energy conspumption - typically about 20mA for 5 mm diodes - and they are available in all required colors including white. Their disadvantage is in a higher price and their directional characteristics, they normally emit light in angles of 30 - 70 degrees. Sometimes diodes with angles under 10 degrees are available (these can be used in reflectors.) Therefore, it should be kept in mind that the diodes' directional characteristics for position and flash lights must be adjusted. If it were not, the model would not be equally visible from all the angles which might lead to disastrous consequences. The easisest way to do that is by roughening the tops of the diodes with emery paper. Another possibilty mentioned is by dropping some adhesive from a fuse pistol on the diode. I have also seen solutions based on directing the diodes so that they partially illuminated the wings. I find the first method to be the simplest.
Position of the lights on a model:
The outer lights of real aircraft fall into several groups: anti-collision lights, navigation/position lights, landing and taxi searchlights. The modern military aircraft are furthermore equipped with lights for flying in formation and eventually with special lights for at-flight refueling.
The position lights are on the wings (the left one is red and the right one is green) and on the fuselage (often at the highest point of he tail in white.) Anti-collision lights are on the top and bottom of the fuselage in red or white. They flash with 1s frequency, are phased or independent. Landing and taxi reflectors are white, in the frontal part of the fuselage, on the wings or on the landing gear.
Visibility of lights in all regimes of flying is crucial for controlling of the model at night. I recommend, as long as it does not affect the quality of your model, to use couples of diodes at the ends of the wings. Always put one diode on the entering side, oriented forwards, and another one on the trailing side oriented backwards. If the model is above your head and the diodes are roughened, everything is OK. But when you fly farther on the horizon, some diodes get hidden behind the wings and the fuselage. Getting orientation just based on one or two faraway lights is tricky. In the beginnings, always make sure you do not fly out of visibility range.
It is suitable to add at least one light on the fuselage to the position lights so that the position lights form at least a triangle. You will appreciate it when you start with acrobacy - each light becomes priceless. You cannot count on the anti-collision lights as the 1s break between flashes may be longer than eternity.
The landing and taxi lights are not necessary for flying although they may contribute to tye model's visibility and orientation as long as they are on during the flight. They are certainly spectacular. My first impression on my first illuminated model was somewhat mixed, though. Since I live near the Prague airport, I am used to seeing Boeings and Airbuses pull out their landing gear and switch on the lights as the light beam penetrates through the skies. In my case, there was no beam and the effect seemed somewhat weak to me. I intentionally used a white 10 mm diode with the angle 10 degrees and I did not roughen it. I thought it would be the right reflector. When the model is on the ground and you illuminate something, it is spectacular. But when the model is in the air, the light does not illuminate anything and the light beam is not visible. You can only see the intensity of light when you stand in the line of the model but the surrounding spectators cannot see the effect. It is suitable to combine the narrow reflector with wide angle diodes.
The simplest LED linkage:
The voltage under which an LED lets through the nominal current depends slightly on the type and producer, but first of all depends on the color. The lowest voltage is required by red diodes (around 1.8 - 1.9V), then yellow ones (1.9 - 2.0 V), green-yellow (over 2V), green (around 3V) and finally blue and white ones(3 - 3.5V). After this limit is exceeded, the current running through the diode increases sharply until the diode gets destroyed.
If you to decide to place on the model only permanently lit position lights, you basically do not need any other electronics. It is the cheapest and the lightest solution. The LED must be connected in the circuit through a resistance that will limit the current to the nominal value. The resistance value must be calculated so that it would burn the difference between the accumulator voltage and the voltage required by the diode. 
We compute the resistance value using the equation R = (Ua - Ud)/ Id, where
Ua = accumulator voltage,
Ud = voltage in LED diode at the nominal current
Id = nominal current through the diode, usually 20mA.
In order to not overload the diode, we must count with the voltage of a fully charged accumulator. As the accumulator's voltage decreases, so will the luminosity of the diode. You will certainly install more than one diode on the model. Then you can repeat this serial combination any number of steps. Five diodes with a current 20 mA connected purely parallelly would take 100 mA. That is just a few percent of the drain of the engine. In ten minutes flight such a connection consumes approx. 17 mAh which amounts to 2,5% of the capacity of a 700mAh accumulator. A substantial part of that energy is lost at the compensating resistances. The higher is the voltage of your accumulator, the higher will be their share. For a 7-cell- accumulator that amounts to 75% of the total power supplied for illumination by the accumulator.
But it is possible to connect more diodes serially. If you have the above-mentioned seven-cells accumulator on your aircraft, three red or two green diodes can be connected serially. So in two branches you can light five diodes at 40 mA only. It is possible to combine different colors in the branches. The resistance is calculated by setting Ud equal to the sum of nominal voltages of the different diodes. Resistance decreases as the number of serially connected diodes increases but at the same time, as the accumulator voltage decreases, the current running through the diodes will decrease till they stop emitting light when the accumulator voltage falls to the value of sum voltage.
Powering LEDs from a power source:
 It is better for LED diodes to be supplied from a power source than through a resistance. In such case, it is not necessary to calculate the resistance values. The current running through the diode as well as luminosity is constant in the wide range of supplied voltage as long as the source voltage is high enough (1.2 V).
Installation procedure:
The typical connections are shown by the schemes for the different types of NF. Number, color as well as position of diodes in circuits in a specific model may vary. You may check function of the unit by connecting it to the accumulator. The function of circuits can be checked by putting diodes on the circuit's contacts. In that way it is possible to check the diode's color as well. If the entrance voltage is observed, there is no danger for the diodes. Reversal of polarity on the contacts is not destructive. Trying diodes. DO NOT TRY the diodes by connecting them directly to the accumulator. Without a compensating resistance you would destroy the diodes.
The next step is design of location of the LEDs and wires. It is useful to keep certain rules to make sure the model is visible in all positions and that night flying be safe. Unlike bulbs, ultra bright LEDs are narrow directional light sources. They light with angles 15, 23, and 30, rarely 70°. The directional characteristics of diodes should be adjusted so that they not are badly visible from certain angles. The easiest way to do that is by roughening them with emery paper. It is also possible to drop some adhesive from a fuse pistol on the diode, or combine these two methods. For instance, if the wing has a thick profile that could hide the position light in some angle, it is better to put two lights there, one on the trailing edge and the other one on the entering edge and direct one forwards and the other one backwards.
Installing the lights on an accomplished model is not trivial. It is easier to start with a new model. With models made of EPP it is possible to cut in the material two slots of approx. 2 mm depth and push a thick enameled wire into them, and once in every couple of centimeters drop adhesive on it. If working with thin enameled wires, it is important to avoid mutual contact. Enamel is not suitable for flexible joints, it could break or wear through but it is lighter than the included wire. If the weight is important to you, you may combine enamel with the included flexible wire. The wires should not form surface loops. Both wires should go as close as possible to each other. The do not produce interference. However, they should not run in parallel with the antenna. They could affect its sensitivity.
An independent power source can be used to power the illumination but it is easier to connect a NF-1 RC unit to the engine's accumulator as shown on the picture. The total average current consumption taken by the unit from the source, counting all the circuits is approx 55 mA at a seven-cell accumulator. During a 10 min. flight the illumination only consumes a little more than 1 % of the 700-mAh-accumulator capacity.
The cabling must be designed with respect to disassembling of the model. It is possible to use additional connectors or serial adaptors that can be made or ordered. It is not possible to use servo-cables adaptors for serial connection of diodes (those are for parallel connection.)
At serial connection of LEDs it is necessary to ensure that the sum of voltage on the diodes plus approx. 1.8 V (for the NF function) be less than the source voltage. If the supplied voltage falls to this value the regulation stops working and the current running through the diodes and the luminosity falls. In calculation, do not use the voltage of a freshly recharged accumulator; rather measure the voltage after landing. Table 1 shows orientation voltage values on the ultra bright LEDs depending on the color. The circuit regulates the current by burning the voltage difference between supplied voltage and the diodes voltage on a transistor. The least favorable situation is when the circuit is powered with a high voltage and a short-circuit happens on the output. At this moment all the power (current multiplied by voltage) is converted to heat in the transistor. The used transistors cannot burn more than 0.25W in the long term. At the given current that represents a maximum voltage of 12 V. If at least one diode is connected in the circuit, that improves the situation of the transistor leading to a maximum operational voltage of 14 V (12 V transistor + 2 V diode). With a higher number of diodes, it is theoretically possible to use the circuits with voltage up to 17 V (12-cells-accumulator.) However, the guarantee does not apply to such use.
When connecting the diodes one must observe the polarity. The positive pole has a longer outlet (a) The negative pole has a trimmed edge (b) and normally has its own chip and extends inside the body (c) See the picture:
Making the cabling:
Whether you use the supplied cable or your own material, it is necessary to prepare cables with a sufficient reserve. A few centimeters in excess can be hidden but just one missing centimeter will cause you trouble. Before connecting the diodes remove the insulation from 5mm of the cable and tin the diode and the cable. This will shorten time needed for soldering. If you put insulation over the connection, prepare 9mm-long pieces of insulation. They shall be pulled on the wire beforehand as far as possible from the intended soldered connection – if not, they could dwindle in a wrong place. After soldering in both stems and cooling pull the insulation on the connection and heat it gently from all sides with the solder so that it would dwindle (you need to try it). It is recommended to heat at a place behind the tip where the solder is clean. Thus the insulation will not be contaminated with remnants of tin and resin.
After fixing the diodes and checking the length we must connect the connectors. They could be crimped without soldering but if you have the solder in hand and do not have the tools for crimping, I recommend soldering. Divide the couple of wires for about 20-25mm and remove the insulation of 4mm of wire and tin it. If you are not fast, the insulation will recede a little more. Shorten the un-insulated tinned wires to 2-3mm. Break off two sockets and gently clamp them parallelly in a clamp at a distance at which they will be in the connector. The included fork adaptor can be used for clamping as well. Ideally you fix the sockets and the wire on a surface area. Drop a little tin in the middle part of the socket, not too much. The thin tube tin is easier to dose. Put the wire in the farther socket and heat it so that the tin connects. Then repat it with the closer socket. See to it that the wire and the socket would be in line. If your hand slips, you can heat the wire again and when it gets released, fix it. Keep eye on the solder temperature, you might lose the insulation. Keep the same polarity with all the cables, it is aesthetical. If you e.g. solder the diodes’ positive pole on the farther socket, the locks of all connectors will be oriented upwards. Bend the borders of the channels round with flat pliers. Then bend the plates around the insulation and finally put the sockets in the connector so that the locks would lock on. If there is resistance, gently try to lift the lock on the connector with a tip. Not too much, otherwise it will stay open forever. Lean the tip at the edge of the socket and gently move it forward. You probably used too much tin or bent the borders too little.
Interference check:
The NF circuits have short-circuit-proof sources that are functional until the circuit's limit supply voltage is exceeded or it is overheated. Thus the circuit protects itself and the connected LED diodes against a sort-circuit of the lights circuit. However, the circuit cannot resist big short-circuit currents and interference frequencies that come from outside sources and pass through power distribution. Therefore we recommend a spatial (and on big models also an electrical) separation of the lights circuit, the power circuit accumulator-regulator-engine and also the receiver's antenna.
At today's currents running through engines, an insufficiently shielded engine is a source of interference that radiates into a space of approx. 20cm of supply cables. If lights are connected to the same source, up to 2m of cables may be added. That is up to ten-fold growth of length of radiator that will not improve the situation in the model. Thus it can happen that an aircraft that used to fly without problems starts plucking after installation of lights and stops responding to control in certain stages of flight. After installation it is better to check the model's behavior on the ground first.
If interference occurs, it is necessary to check the installation of the power part and it is suitable to connect a small anti-interference member to reduce the degree of penetration of interference in the lights circuit. The best is suppressor and if it is not available, an RC unit is sufficient. The resistances are more easily available and furthermore, they can safely limit a possible short-circuit current.
Starting:
You may ask the question: Will the model be really visible? Will I be able to pilot it? It is not that worse than at daytime. For your first flight, go out after sunset, before the sky is really dark. Try a circle and you will discover that you can't really see the lights and you pilot based on the dark silhouette you see. Land, and start again after 20 minutes. The sky is quite darker, the model's silhouette is totally black and when the model flies close by, you will notice glimmering lights. No, that cannot work. Land, and try again after another 20 minutes. It is totally dark. You can touch the model on the grass only thanks to the fact it is bright and there is starlight (do not forget your own light). Turn the power source on. The light will blind you and you will discover that the model can illuminate the land when lifted above your head. Take off and fly, not too far nor too wildly. Then you climb until you can just sense the lights, make sure you do not fly too far away, and then go down and a low flow around so you illuminate the ground. The experience is worth it. You will find that flying at daytime is rather boring. | 
