Confederation Marine Modellers
(latest at the bottom)
Neat wiring
Winter storage of our batteries.
Building tips - Radio & Electrical
Connectors are something that we don't normally need to be interested in or concerned about. They generally come with the parts we buy. If we need to connect two devices which have different connectors, it's usually a personal preference which one we change.
Most connectors are either single wire or two wire, the exception being servo connectors which are 3. The advantage of the two-wire types is that they are usually polarised, meaning you cannot connect the positive to the negative and vice versa.
The best connectors are gold-plated, because gold is an excellent conductor of electricity, but for most modellers it won't make a noticeable difference to use a connector which is not gold-plated.
Mating connectors are referred to as male and female, and this always refers to the pins, not the connector casing.
1. Bullet (Panduit)
These are commonly fitted to the popular Mtroniks Viper range of marine ESC's. Best information available suggests they are made by Panduit and are mainly intended for automotive use, since they can be obtained locally from Canadian Tire or Sayal. No amperage ratings have been found and you would have to assume that they are good for the rating of the wire they are meant to be used with. They are crimp-type connectors.
2. Tamiya
These are also fitted to the Mtroniks Viper range. There are similar connectors made by Molex, which may or may not be interchangeable with the Tamiya. They are rated at 15 Amps maximum and were once very popular, but other styles are becoming more common. They are quite large for the 15A maximum current they can handle. Tamiya connectors are easy to plug/unplug and have a sprung locking tab. They require crimping the wire to the pins but you can also get them with short wires already crimped allowing you to just solder the wires to your device or battery.
3. Mini-PV (Servo)
These are the 3 pin plugs which are fitted to servos. The outer white or yellow wire is the signal wire and is not fitted when these plugs are used for power supply. They are rated for 3 amps steady load. Another crimped connector, but usually available with short wires.
4. JST RCY
These are often referred to simply as 'JST' plugs but their correct identification is 'JST-RCY'. They are rated 3 amps at a steady load. Also a crimped connector available with short wires. 4f is the female plug and 4m is the male plug. There seems to no requirement as to which plug is used for the battery - it will be as required by the device.
5. Deans
These were the first heavy-duty connectors and are rated at 60 amps steady load. There are many clones available, some good, some bad. Some have textured surfaces, which makes them easier to separate. The ones with smooth surfaces can be difficult to disconnect and benefit from having a piece of wet-and-dry paper glued around them. The plastic body on Deans plugs is fairly heat-sensitive so you have to be careful while soldering to avoid softening the plastic which can loosen or misalign the connector tabs. Some clones actually have better heat immunity than the originals. They have flat strip solder tabs on the back which need to insulated with heat shrink.
6. XT
The XT range of battery connectors comes in 3 sizes, XT30, XT60 and XT90, the numbers indicating their amperage rating. With all XT style connectors, wires are soldered to small external hollow pins on the back of the connector that also need to be insulated with heat shrink afterwards. This also makes them easy to desolder and replace/reuse. The connector housing material used is very heat resistant so XT style connectors are more resistant to pin loosening due to overheating while soldering.
7. Bullet connectors (Gold-plated)
If you search on the internet for 'bullet connectors' this is the style you are most likely to see. Some brushless motors and ESC's are supplied with these on the connecting wires; because there are 3 wires bullet connectors are the only option. Some batteries and devices have bare wires so again these are a good option. Ratings range from 20 amps for the 2mm diameter to 200+ amps for the 8mm diameter.
8. Traxxas
Traxxas batteries are now supplied with Traxxas' own design of connector. They are available with several adapters included, enabling them to connect to other styles. They are easy to plug and unplug but can be tricky to solder wires to.
These are not the only connectors you can find, but the most common ones. For more information try these websites:
https://www.rchelicopterfun.com/rc-lipo-battery-connector.html
http://www.tjinguytech.com/reviews/rc-connectors
If you are thinking about using Lipo batteries for the first time, or are looking for a refresher, take a look at this webpage: https://rogershobbycenter.com/lipoguide/.
Reliable wiring
Elevon control - an explanation by Rowen
There will be occasions when you want more than the 90° rotation that manufacturers set their servos to. Most of the servos I have come across are capable of more than the 90° rotation that we normally use. In fact, many are capable of as much as 180° rotation.
One method of getting the extra rotation uses a feature found in some modern radios. You may discover that it has an "end point adjustment" facility. If you only need a little more than 90° rotation this facility may be all you need.
If you need more than the radio can provide, or your radio does not have the facility, the second method is to connect a "servo stretcher" between your radio and the servo.
There are two varieties of servo stretcher, with and without end point adjustment. Some servos cannot rotate the full 180°, and a stretcher without end point adjustment may try to make your servo rotate the full 180° or more. If your servo rotation hits an end stop and cannot get the rotation that the stretcher calls for, then the servo motor stalls, keeps trying to reach the set limit, gets hot, and may burn out. To ensure you don't face this situation, you have to limit the amount of rotation.
You may be able to limit the rotation using your radio's end point adjustment, otherwise a stretcher with the facility is necessary. Robotzone make a stretcher with adjustable endpoints, currently available from Servocity and Active Robots. Stretchers without end point adjustment are available from a number of suppliers.
Servo stretchers.
Prevent chafing
Servo plugs
Here are four servo plug and wire lead diagrams. We've included these for all those
pilots and modelers who like to swap radio gear between airplanes, or who like to mix
and match receivers, servos, and battery packs. Note that the plus (+) and minus (-)
leads are common across the receiver bus.
However, make certain that these leads are not reversed in the servo plug! as such a
situation will likely cause damage to the servo, resulting in a trip to the repair shop. Also, you should know that while in most cases the signal to the servo is interchangeable between brands, there are certain brands that utilize a different shift on the signal—either positive or negative.
Information from 3-D Flyer magazine.
Doug showed the meeting an example of using the copper tape which is common in doll houses. The tape consists of two conductors side-by-side on a self-adhesive backing. THe tape can be stuck to internal walls, soldered to, and painted over to conceal. For more information:
http://tinyfixation.blogspot.com/2012/11/tutorial-tape-wiring-dollhouse-basics.html
Rick told us about some epoxy which he had obtained from Noah's Marine in Etobicoke and was very economical, at $28.30 for 12oz. Look for Ark Composites Epoxy Repair Kit.
Hints and tips - LED drivers: eliminate the resistor.
Hints & tips - Servo plugs
Soldering wires
Stick a piece of Velcro to a suitable place on the hull or frames, then arrange the wires across it. Trap the wires by pressing the matching Velcro piece over them.
Have you struggled trying to hold a couple of wires together while you solder them? There are a number of tools to help you.
The most commonly-advocated tool for doing this is the “helping hands” or "third hand" tool which has a couple of crocodile clips, at the end of a bar, which can be rotated to different positions. This tool is great if the bare wires are looped and twisted together so they're locked mechanically before you apply solder, which is the method most professionals recommend. It works well if you are soldering a wire to a connector, if you can mechanically fasten them together.
However, many of the connectors we use have no provision for a mechanical connection, you simply lay the wire on the terminal and apply solder. Many of our wire-to-wire joints work fine when they are only held by solder. A disadvantage of the above tool is that, if you just want to hold the bare wires together for a simple, low-strength, soldered joint, you can't get the clips near enough to each other to hold the wires firmly close together, without a lot of fiddling. You could use two 'helping hands', then you can position two clips as close as you want. This is better but suffers the problem you have with all crocodile clips. The jaws of the clips are serrated, and the grooves don't line up neatly. So the wire goes off at an angle you didn't expect. The wires themselves can be bent and twisted to line them up; sometimes they don't want to stay where you want them to. With patience you can juggle around with the wires and clips and line them up.
Yet another tool, no clips this time, has a set of tapered slots set in two vertical ribs. You push the wires down until the slots grip them. There are no clips to rotate, so you can only bend the wires to get them into position. It works, but not a lot better than the other options.
All of the above will work, some require more patience than others. My near-perfect solution works quickly every time. I have two pieces of tacky putty (blue or white, whatever you can find), set 1/4” to 1/2” apart, attached to a base. You press each wire into the putty, or a wire and a connector, so that the bare ends are in contact in the space between. It's easy to get the two ends in line. Simple ! What's more, this simple little fixture lets you solder wires in tight spaces where none of the other tools would fit. This 'tool' can be made very easily from scrap wood, shown here, or scrap styrene.
Even if you can hold the wires firmly in position, don't forget the other criteria for making a reliable joint.
- make sure the wires are in contact; with stranded wires you may be able to push them end to end into one another a little way
- make sure the iron is up to full temperature
- apply just enough solder to the tip of the iron to wet the surface
- touch the iron to one side of the joint and the solder to the opposite side; when the solder melts you're sure that both wires are hot enough
- the finished joint surface should be shiny; if it's not you probably moved the joint as it was cooling. So reheat it.
Rowen has used this technique on his models to control brushless motors. He found that using differential motor control for steering could be difficult. The brushless motor response is so rapid it is impossible to do anything gently. For steering he tends to use rudder control on the LH stick when running at slow speed or when in confined waters, and turns using Elevon differential motor control on the RH lever at speed or on open water. Differential control will probably be smoother when using brushed motors.
In his article above, Rowen mentions the use of a LED driver. These are extremely useful devices and can take all the headaches of figuring out how to wire your LEDs. Simply insert one into your circuit and your 20mA LED will light up as it should.
This simple device limits the current through itself to 20mA. When a voltage is applied (anywhere from 2 to 45V) it will actively adjust it's own resistance to allow just 20mA (+/- 3mA) to pass through. This makes it a perfect replacement for current-limiting resistors in LED circuits, and you won't have to calculate resistor values or worry about a varying voltage source.
The current limiter can be placed anywhere in the loop with LED's, but needs to be placed with the proper orientation, or it and your LED's could be damaged. The board has 0.032" solder holes which can accommodate wire down to 22AWG (tightly twisted) or standard 0.1" header pins. Note that at least ~2V across the current limiter is required for proper operation - below that and the current output will start to decrease and the LED's to dim. Multiple current limiters can also be placed in parallel to add current (40mA, 60mA, etc...).
Units are provided on a scored circuit board that can be broken apart using pliers and/or strong fingers. Size: 0.334 x 0.100 x 0.077".
More information can be found at: https://lighthouseleds.com/20ma-led-current-limiter-driver.html .
NA number of members have looked enquiringly at the version of this radio that I own.
Some years ago it was available from Harbor Models in the USA, but not recently.
It is now available from two suppliers in the UK, Howes Models and Cornwall Model Boats.:Howes Models F14 and Cornwall Model Boats F14. This version contains one twin-stick, ideal for twin-prop control, and one single stick. It is an 8-channel radio. The single stick could be replaced with another twin-stick if desired, available from Robbe in Germany.
These versions operate at 40MHz so they must be converted to 2.4GHz for use in North America. Fortunately this is fairly easy to do using the Assan 2.4GHz hack module available from Hobbyking: Hack module., a conversion that I have already done. Step-by-step instructions can be found on Youtube.
That's the good news. The bad news is that the radio will set you back £200 (~CDN$330) and the Assan hack module US$50 (~CDN$63).
Update: Mar 2023. The Robbe radio and the Assan module appear to have been discontinued but you may be able to find an equivalent via the internet. Roy C.
Wiring and epoxy.
Robbe F14 Navy radio
1
2
3
4f
4m
5
6
7
8
Resistor values for LED's.
If we have a need for 300° rotation in a servo it has been necessary to get complicated to achieve that. Even getting more than 90° has required the use of a servo stretcher added to a standard servo. This 'goBilda' servo is capable of 135° out of the box. With the addition of a servo stretcher it will produce 300° rotation.
The servo costs US$28 from Servocity. and gobilda.
Save your servo wires from chaffing on bulkheads and when passing thru fiberglass holes by making little grommets out of scrap fuel tubing. Slit them length wise and slide over servo wires. Keep them in place with wire ties or a little Zap glue.
If you will not be using your LiPos for more than 24 hours, then put them into storage. Charge or discharge them to 3.8V per cell, securely place them into a LiPo Safe Bag, and find a shaded area that is at room temperature.
Remember, if you treat your LiPos well, they will treat you even better. When properly maintained, LiPos can typically last you up to 2-3 years.
Do take care to install neatly arranged, easy-to-trace wiring throughout the model. Solder all connectors to insure current flow and keep all wires up out of the bilge area to prevent exposure to normal bilge water.
Connectors
Affix two brass bolts so that they protrude from the transom. Connect these to your battery terminals, if desired via a changeover switch, with the positive (red) terminal on the port side, and the black (negative) terminal on the starboard. These become convenient charging terminals. They could also be placed on deck and take the form of brass bollards or cleats. This idea eliminates the need for another terminal in the radio box, where a charging socket would usually be. Use alligator clips to connect the charger.
Most of us are delighted when our model just responds to radio signals and performs properly. Typically, we use a “lever” style transmitter (Tx) and on a twin motor vessel, if seeking individual motor control, one motor is controlled by the up/down movement of each lever. This works well but has some limitations. Both hands need to be used and rudder effect is easily masked by inadvertent motor operation. This is particularly apparent on faster models with a brushless motor installation.
There was an article published in “Model Boats” magazine in March 2019 suggesting another approach. All of our RC equipment was generally developed for model aircraft, for that is where the volume market is. However, sometimes features are offered that boaters would not usually use. On some of the more sophisticated Transmitters (Tx) both “Elevon” and “V-tail” mixing are available. These link two radio functions together so one control lever can operate both features. I will describe the “Elevon” as it is the one I use on my Flysky Tx, although both functions are offered.
"Elevons" are control surfaces on delta wing aircraft where the functions of elevator and aileron are combined. My Tx is the “Mode 2” style where elevator and aileron controls are on the RH lever. In aircraft with separate wings and tail, the Forward/Back stick movements operate the 2 elevators and cause the aircraft to pitch up or down, and side/side movements operate the 2 ailerons and cause the aircraft to roll. When the 'elevon' control method is used, the same stick movements cause the same aircraft motions but operate only 2 elevons.
On a model boat, elevon control puts both ESCs on the RH control lever. Moving the lever up operates both screws in the forward direction and down into reverse. Going from side to side speeds up or slows down either motor, so the boat goes in the direction the lever dictates. Rather more intuitive than before. After setting this function up and then testing it, I decided it works well. This was accomplished by:
- Establish the Tx Stick mode, mine was # 2.
- Considering Elevon, determine which layout allows the Aileron and Elevator controls to be operated by the same lever.
- Use 'Elevator' for throttle (fwd & astern) and 'Aileron' to “turn”. The 'Aileron' will accelerate the motor on the outside of a turn.
- Reallocate channels on the Tx so Port & Starboard motor ESCs become channels 1 & 2 respectively. Use these channels on the Rx for the appropriate ESC.
- Select “Elevon” mode on Tx.
- The RH lever now controls both motors.
- The LH lever (side to side) can now be used for rudder and the up /down function for any other feature needing proportional control. I use it for the centre brushed motor on my triple screw model.
Your Radio instructions should give detailed information on setting up the radio.
If you are fitting LED lighting to your model, and need to work out what value of resistor you need, refer to the quick reference guide here.
Building Tips - Radio and electrical
Servo with 300° rotation.
All you need to know about LIPO's
Member's tip from Garth: Use an empty Tylenol (or similar) bottle to house your receiver and to make doubly sure it doesn’t get wet, seal it with tape or Silicone.
Regarding year-round storage of Lipo batteries:
External charging terminals
Protecting your radio receiver
Bob Ide ©