Norcim rc electronics club page 7……

SOME USEFUL LINKS……NITROTEK GLIDERS

THE BEAUTIFUL LOBMASTER FISHING BOAT BY KYMODEL This superbly hand finished model boat comes complete with 40 MHz radio equipment and fully installed electric motor with forward and reverse speed controller. The packaging of this delicate model has been really well thought out to transport the goods around the world without damage. The full size four channel transmitter (SPRING RC FM TF412S) and fully installed receiver uses only two channels with two to spare. Unfortunately with the sample supplied, the two used stick movements, left stick forward/reverse, right stick left/right rudder, were very stiff (see picture showing left and right sticks not centring). (Oddly the other two unused control stick movements had perfect centring). With a boat perhaps, this did not matter too much. If however the transmitter was used with a model aircraft (35MHz version) then the stick problem would cause difficulty. The Transmitter is supplied for use with eight AA dry batteries. Unfortunately with new batteries installed and the antenna extended, the boat steering servo and speed controller produced only frantic erratic movements. The fault was not ‘swamping’ with the Tx too close to the receiver as testing with the Tx some distance away produced the same erratic lack of control. With trial and error it was found that if the Tx was switched on with the antenna collapsed…….then control was available. If the antenna was carefully extended at this point, control remained available.

Without further testing with a spectrum analyser it would seem that some form of RF (transmit section) instability was causing the fault. The Tx is supplied with a charge socket so perhaps the lower voltage of rechargeable batteries may help? (the IKEA alkaline batteries were giving 12.5 volts…..rechargeable would give a lower voltage of 9.6 volts). Initial testing with uncharged nicads showed that this could be the answer but after a full charge of the NI-MH batteries used, the problem still existed. The 150 milliamps current with the Tx antenna extended (200 milliamps closed) should give around ten hours running time with 2000 mah rechargeable batteries.

So at the moment The Tx has to be switched on with its antenna down and then the antenna slowly extended. Only a shine at a spectrum analyser would show whether RF instability is the cause of the fault.

Update…Reducing the Tx to seven cell NH operation seems to have cured the instability problem. The reduced  (if any) output from the Tx is barely noticeable and the battery indicator (green) still operates OK. Lowering the battery pack to just seven cells was done with a 50mm length of 5mm dia round silver steel rod (any metal would do). Some caravan Calor gas rubber tube was used around the outside of the rod to effectively look like a standard AA battery! It simply replaces one (any) of the eight cells.

Update 2….The spring centring of the joysticks was greatly improved by reducing the length of the tiny springs in the joysticks by two turns. This was a fiddly job and time consuming.

My Guess about the above problems is that these transmitters were initially intended for aircraft use and set up for 35 MHz. However the immediate problem with joystick centring made them unsuitable for aircraft flying.  40MHz is not too far away from 35MHz so 40MHz xtals were tried and seemed to work. The time involved in taking the Tx apart to re-tune and fix the mechanical centring problem simply was not economic. So this Tx found its way to a model boat environment. Having said that, the SpringRC transmitter is of superb build quality.

The boat battery supplied is a sealed lead acid 6 volt 4 amp hour and should give well over an hour with normal speed control use. These are pretty standard batteries and I have just got another spare one from my local radio store for just £6.00. Unfortunately, these batteries have standard auto spade type connectors and the boat input connector is of the Tamiya type. So before any playing about could be done, we had to make up a suitable ‘Spade to Tamiya’ connector lead. (Two Lobmaster freight cartons were opened to see if a suitable lead had been left out but both the same). The charger supplied with the boat battery (model CH24-1.8T) gives a very safe automatic cut-off charge. A red led indicating charge. This turns to green when charge is complete. Full charge can be relatively quick in around five hours. Part charge taking less than this with auto cut-off. The receiver switch is mounted under the deck. This means that at the pond, all the rigging needs to be unhooked and the decking removed to switch the receiver on, followed by re-fitting the decking and rigging. It is a simple job to reposition the switch above the deck (see picture showing the existing switch above deck and hiding in a hole made in the wheelhouse to keep it away from water). As the current draw from the drive battery is very low with the Rx switch ‘OFF’ (Just 15 milliamps, giving over 200 hours in this ‘standby’ state) you can plug the drive battery in at home before going to the pond, and unplug when you get home! That way the decking/rigging does not need to be disturbed at all at the pond.

First launch with the LOBMASTER showed an obvious list to one side. Checking the position of all the installed components did not answer the problem. In the end four ounces of ballast was added to the left hand side of the battery to get the hull looking level in the water. (see picture). The shiny cylindrical thing used for ballast is an auto plug spanner! As the present transport to the pond is diesel then this keeps the plug spanner thinking it’s still doing a useful job…!!

The ‘SPRING RC’ system comes with no instructions. The Tx has RED/GREEN/YELLOW Led’s . Plus an audio bleep system. At switch-on, all Led’s illuminate. The Yellow indicates that a Xtal is inserted and working. The Green indicates battery condition and begins to flash WITH BLEEPING if battery is low. A continual BLEEP means YOU AINT GOT MUCH TIME LEFT !  The Red led illuminates at switch-on and does not seem to do anything except ‘go out’ when the battery is completely exhausted.

At around £150 for the whole package, The Kymodel LOBMASTER represents brilliant value for money. Just hope the above problems were a one off and not a result of a bad batch of R/C systems. Availability of genuine ‘SPRING RC’ plug-in crystals for a change of frequency spot, or replacement, appears to be a problem at the moment.

FLYING HAS INCLUDED THE ART-TECH WING DRAGON  (Looks like a model of a real Micro light!) This version is the one with ailerons and comes almost ready to fly with completely installed radio gear! The four channel transmitter has really good sticks with ratchet flight trims and servo reverse facility is there should you need it. Best of all at the package price is the CE approved 35 MHz plug-in Xtal specification so you can fly the model at your local club too. At the model end, there are four superb micro servos (one in each wing!), a mini receiver and a 30 amp speed controller for the 400 pusher electric motor. Included also is a Flight Simulator CD to stick in your computer and practice flying before the real thing.

OK…so much for the goodies in the box but is the Wing Dragon just another Xmas toy that doesn’t really fly well enough for the real veteran R/C modellers out there. Well I’m one of those privileged people and after the first few minutes of flying, I can honestly say that the Wing Dragon is one of the most beautifully controllable machines that I have ever flown….and I can’t wait to get back to the field for another session! The climb-out from a hand launch is without worry or hassle and altitude is easy achievable. Once up there, loops, rolls, and tight turns make the model so easy to place just where you want it. Landings can be those nose down things if you wish, with a last minute flair-out which slows the model to an almost snail pace…still with complete control…..almost helicopter like in a 10mph breeze!.....MAGIC !! Throttle response is instant and completely proportional. This is a really nice model to fly and the designers simply have to be complimented on this one.

With the R/C gear switched on for the first time I noticed the elevator and rudder were slightly off centre. Using a pair of pliers to grip the piano wire control rods, a few turns of the connecting clevis sorted this. The ailerons were spot on. The first flight was completed without any necessary in-flight trim!

Even a CG check was done with the battery installed……Perfect!

Using the supplied wall charger for the flight battery, I did initially notice a rather short flight time. Following this up I found that the charge time suggested by the manufacturers of 3 or 4 hours maximum in the instructions must have been well on the conservative side! The supplied wall charger Model Number 35090030-B2 was charging the eight cell 1000mah battery at around 120 milliamps. So to get the battery from exhausted (last flight with the motor cutting out) to a fully charged condition, then many more hours were required! Mathematically we needed 9 to 10 hours at which point the battery becomes slightly warm indicating a full charge. This resulted in flight times increasing by two to three times.

As the flying site used, is a typical grass farmers field…….I removed the wheels to help with skid landings. NitroTek stock the 2.4 GHz version now which is the way to go.

HAVING A PLAY WITH THE ‘ART-TECH’ FLIGHT SIMULATOR  Almost the day after the above was written, a very nice man from Parcelforce here in the UK handed a large box through the door! Within minutes the contents were out of the box and the CD was into the computer…..BINGO! It actually works with Windows XP, using the full double joystick transmitter case supplied….at last I was able to fly a simulated model looking at the computer monitor. The behaviour of the model is extremely real and is without doubt a superb educational tool for the beginner to model flying. There are also hours of fun for the experienced flier on a rainy day. Different types of models are available to fly, including helicopters. Different flying backgrounds can also be used. To make things easy for the first few flights you can even slow things down via ‘simulation’…’properties’….then change the ‘sample time’ from 0.005 to say 0.05. When you get the hang of things then a more realistic flight speed can be had by changing the ‘sample time’ back to the default setting of 0.005 secs.

This package at around £30 plus p&p is absolutely worth buying even for the veteran flyer like myself. The package includes a complete transmitter case with two joystick units including in-flight trims. A CD is included to copy to your computer. The internal circuit board in the joystick box uses a pre programmed mini computer chip and a 2 Metre USB cable is included to plug directly into the USB input of your computer. Excellent value!

My package arrived With the throttle on the RIGHT of the Transmitter box……although I can fly this way, I can fly better with the throttle LEFT. With four self tap screws to take off the rear of the case, and a fiddle with springs and throttle ratchet spring I finally had the control box working with a left hand throttle. There is an alteration of the channel sequence required, this comes up when setting up the ‘calibration’ on the PC monitor. Simply delete the numbers shown and replace with (from the top) 4312 4312.

The downloading of the CD puts a shortcut on the desktop. Double clicking this, immediately starts the model take-off and this keeps going till you crash! To start again, simply go to ‘simulation’…and click ‘initialize’…make sure you have some throttle on and the model starts again. MAGIC for a rainy day! Several model designs are available in the download including the Wing Dragon and they all behave differently. So if you are eventually going to fly the above Wing Dragon…..then practice will help to make perfect.

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Flysky FS-i6X 10CH 2.4GHz AFHDS 2A RC Transmitter With FS-iA10B Receiver £44.79! (useful link)

AN INTERESTING WEBSITE!......they supply some hard to get items, such as…suitable output transistors for the 35MHz transmitter circuit shown in the Norcim page 3….2N4427, 2N5109, and MRF237 are all possible TO39 package devices. A possible surface mount output transistor is also listed as BFG193. Also there are items of interest such as the MC3361DW which is the surface mount version of the 35MHz receiver chip circuitry (Norcim home page). Other items include suitable ceramic FM receiver filters….CFWS455G and CFUM455G. Ferrite beads are there too and an interesting ‘Quad Coil’ with possible use for the FM discriminator coil in the receiver (may need a damping resistor across the coil to keep the discriminator output down to around 0.7 volts….try 270K or lower!). There is also another possible radio control receiver chip listed…the SA626D but it would need development based on the 3361 circuitry. These people can be found at http://rfcandy.com/

WANT TO TRY A 2.4 GIG SYSTEM BY JUST USING YOUR POCKET MONEY?

Well this Combo will knock you back just £26.00 ! plus post and packing! You will need a few spare standard servos and a receiver battery. The four channel transmitter AND six channel receiver come in a plain cover box (so nobody including the postman will know what you are buying!!)  WITHOUT instructions! However, as the transmitter case is so similar in layout and build quality to a basic Futaba system then all the controls and usage will be familiar to the average flier or boat user There are simple instructions available to download from the site. The Tx has servo reversing switches and even a mixer switch in the battery compartment! The quoted 800 metre ground range of this FHSS (Frequency Hopping Spread Spectrum) system, make it well suitable for flying. The six channel receiver is small and uses a hard case (not just heat shrink) and looks remarkably like a Futaba product!. The transmitter and receiver have to be ‘registered’ to each other. (This procedure is similar to registering a wireless keyboard or mouse to a USB receiver.) With both Transmitter and Receiver switched ON, simply press the small (No not ‘small’) very tiny button on the end of the receiver, you will need a tiny screwdriver for this and you will feel/hear the button click. A green LED flashes, inside the transparent case, for a couple of seconds and Bingo, the servos begin to work and the system is ‘Channel Hopping’ and ready to go, as they say.

There is also a six channel version of the system if you are prepared to save your pocket money up for a couple of weeks!

This system was installed and working in a boat within minutes. Servo reversing switches very handy and used. Now several hours sailing with rock solid control and literally out of site range! The Tx is very comfortable to hold with the sticks perfectly positioned under the thumbs. Joystick movement is smooth and centring excellent. The throttle stick ratchet is light and gives thirty positions, perfect for aircraft. Smooth ratchet trims too! The 95 milliamp current consumption of the Tx means typically 20 hours use from NH batteries.

Hey……no more checking who’s on what frequency, no more bent aerials, no more washing line pegs, no more box of crystals, no more waiting for a frequency, no more poking some ones eye out….just simply join the crowd at the lake or flying site and switch on! This is leading edge R/C technology at a fantastic price.

The above Combo was purchased last year and to date has clocked over fifty hours of boating time in the LOBMASTER fishing boat…. OK, OK, not a very taxing job for an R/C system but it must be said that the combo has worked impeccably. The range is out of site. The boat was fitted with an ultra bright LED lamp with pencil beam a couple of months ago. This can be seen in daylight conditions providing the boat was pointing back at the transmitter. The boat can be taken out of visual sight but using the beam can be steered back without problem. More recently a miniature video camcorder weighing less than an ounce was fitted to the boat. This not only shows impressive playbacks when the memory card is plugged into the computer but also records the sound of the speed controller. Even at extreme range, the speed controller can be heard completely smoothly working without any erratic operation indicating any possibility of edge of range condition. This is a truly impressive 2.4GHz transmitter/receiver combo without even mentioning the unbelievable competitive retail cost. Little wonder that many modelling nuts keep going back and ordering more of these units. Incidentally, even after fifty hours of use, the joystick feel and centring is still among the best. The combo was bought some time ago from NitroTek but is not now a stock item.

THE LARGEST COLLECTION OF VINTAGE RADIO CONTROL SYSTEMS IN THE UK has been achieved by two guys called Phil and Shaun of the ‘Single Channel Website’. A latest input to the site includes a rare forty year old micron transmitter and receiver. The age of multi channel R/C systems had well arrived but Micron thought there was a niche in the market for a single channel system for guided free flight models. The transmitter was simple. It consisted of their servo tester with a simple transmit stage. The receiver output plugged direct to the servo. There was no need for any decoding circuitry. As a result the Combo could be offered at a very competitive price. The package failed however and the ELF was taken off the market with less than 100 units sold.

 Phil and Shaun not only collect antique R/C systems but also service and fly many of the examples. The ELF was donated by Phill Wigley.

If you have an old R/C system and want it to live on forever (well nearly) then do consider donating it to the largest vintage collection in the UK.

See Phil’s video about the Elf ?.........

http://www.youtube.com/watch?v=kMhWA2YbqR8

Thanks for reading. ! !