Building Models
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Remote
Controls
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Müritz
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Skipper
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Terra
Crusher
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Radio Remote Controls
At some time during the 70th I started to get interested in remote controlled models. Buying a remote control was for different reasons no option, so I thought to build one myself. Getting a good instruction book is always a good start. So I got myself the below edition of one of our most popular authors at that time. Full of enthusiasm I started the new adventure, still thinking "What's all the fuss about? That can't be too difficult".
Well, there was one thing I had to take care of first. I needed a permit. Living in good old East Germany, nothing was easy when it came to radio transmission equipment. First it needed a permit to build the thing. One had to explain why and what one wanted to build it for. One also had to submit schematics and technical specifications. Then, in case the desired permit was issued, there was a one year time frame to build the thing and present it for final acceptance. If everything was to the liking of the experts, one finally got a license to use it.
The
paper above was issued for my second system after I sold the first one to
a colleague. I actually needed a new permit to sell it and I think you guess
right: YES, my colleague needed to apply for his own permit to be able to
by the stuff from me. Gosh, we really liked permits those days ;)
There was a little funny thing happening when I submitted my first transmitter
for final acceptance. I dropped it off at the workshop where the experts of
our "Deutsche Post" were supposed to check it during one weeks time.
When I came to pick it up again, the guy said in a very friendly manner: "Well,
it seems to work. But I have no idea how you want to control a model with
hardly 10 mW HF output of your transmitter." I was quite surprised as
I before measured about 300 mW myself, which was good enough for a 500 meter
range. The explanation came simple: they had about killed the batteries during
the week! I was quite surprised, the "experts" didn't find out ;)
Of course I kept my big mouth shut and without further problems I got my much
desired sticker to glue to my first brand new radio control transmitter. Whoa,
was I proud.
27,12 MHz AM, 4-Channel Push-Button System
My first system was a very simple 27,12 MHz, 4 channel with push button action only. Though looking back it seems simple now, I admit, I had my problems. Luckily enough I had some friends and colleagues who helped me through it and finally I really got it to work. The range was about 400 to 500 meters. I'm showing the schematics here only for information. Nobody will build such thing anymore.
4-Channel Push-Button
Transmitter
Very Simple Receiver
TF-Selective Switch
(four in total)
Though some time ago my colleague has confirmed the system is still alive and working, I have no pictures of it to show here. There is only this blowup from the Müritz picture that vaguely shows the transmitter.
27,12 MHz AM, 7-Channel Digital-Proportional System
By the end of the 80th I wanted something better. The result was this 7-channel system. As always, about everything is homemade. I was especially proud of the cross control stick. That thing was as difficult as I could handle it at the time.
Below picture shows the receiver with 2-channel decoder underneath, 3,5A speed controller, 4,8V battery and on top a servo from shelf. Originally I even had a self build servo, but it got lost over the years :(
Down here to the left the first 2-channel decoder, right the new 7-channel.
The whole system is presently being build into the "Skipper". Of course one can buy those things today quite cheap and with better performance too. To me that's not the point. Doing it myself is most of the fun. Once things are finished, I loose interest.
Cabin-Cruiser "Müritz"
The Müritz was offered in the 70th as plywood kit. I bought mine about 1972 but did not finish it before 1980. It was controlled by my first 4-channel RC-system as described above. Power source were 4 pieces of 4.5V flat-pack batteries for the motor plus an additional lead-acid battery for the receiver. Controlling the boat trough the 4-channel push buttons was not really that comfortable but it worked.
I believe this picture to be from 1982. We used to go camping at that lake. My daughter and I are preparing the Müritz for launch. I nearly lost the boat at that occasion. There was a stiff wind coming up just when she was about 200 meter off shore. She took a couple of waves and the water coming inside made the receiver stall. I was already preparing to jump in to get her back but she finally made it on her own. That was really close! Later in the 80th I sold her complete with the RC to a colleague. When I met him around the turn of the millennium, he told me that she was still alive and doing just fine :)
Speedboat "Skipper"
The speedboat Skipper has it's own history to tell. Many years ago one of my cousins got a plastic kit for a toy boat. It was a quite cheap one, with not much of quality at all. Except I liked the form of the hull. As the original boat never really got finished, my cousin didn't mind me taking the hull.
Hull & Deck
The way
is was (very thin thermoplastic), the hull was of not much use. So instead
I used it, to create a mold of plaster and form a new hull off glasfiber-resin.
Once the hull was ready I sort off lost interest for a long time and only many years later, while cleaning up my little workshop, I rediscovered it. As the old RC-system was also still around, collecting dust, I decided to put it both into use.
First I glued a plywood frame onto the hull to carry the later deck structure.
The initial intention was to paint the hull red. After this early trial I thought it looked to much like a toy. Therefore I decided to go back to simple white instead.
This little stand was needed to avoid damage of the boat as well as to enable easy work at it.
This picture is ahead of the actual work progress but it shows nicely the elegance of the hull.
The deck was constructed from ledges of pinewood, glued onto a carrier of 2 mm plywood. Some wider ledges were stained in mahogany, whereas the thinner ones stayed with their natural bright color.
Once again ahead of progress but the picture shows the deck in it's final shape before installing details.
Detail Construction
Here is the cockpit ready. All parts except LED's and switch are homemade. The switch connects the battery either to the receiver or charger socket. The red, yellow and green LED serve as capacity control for the battery.
As a little extra I have connected the steering wheel to the rudder servo. Turning the rudder from the RC-system makes the wheel turn too.
Though cockpit and windscreen look OK, the deck still is quite naked. Making the windscreen was more trouble than expected. The material is 2 mm acrylic glass that was formed by use of a hot air gun. It took me several trails to get temperature and procedure right. Finally the result was not as good as desired but acceptable.
The front hatch and searchlight are ready. The hatch serves for checking on the motor but also to connect the battery charger. The searchlight is made from solid brass. Light source is a white 5 mm LED that has a light power of 5600 mcd. It is unbelievable bright. I'm very pleased with it.
The picture shows flagpole and back hatch with hinges and lock. The flag is temporary, only made from paper to check size and color.
This shows the inside part of both locks. A small spring pulls the bolt into locking position.
Almost the whole electronics are installed. What's missing are the two digital switches for lights and siren and the speaker. It really got quite crowded.
Time
for a first bathtub test. And of course Murphy's law hit again. The fact that
the nose points slightly down is OK, I think. When speeding up, it will be
pushed up enough (I hope). What's worst is, that it leans to the left too
:(
That means digital switches and speaker must go to the right and maybe it
even needs some ballast weight.
Electrical Schematics And Components
Block Schematic Skipper
Schematic and function is simple. There is only one battery, consisting of 8 pieces NI-MH AA cells 1,2V 1,3 Ah. The 9.6-5.0V DC-DC module generates the 5V needed for the receiver.
Power Module
This is the DC-DC converter. Only IC1, C1 and C2 are used to convert 9.6V battery voltage to 5.0V for the receiver. The rest is only for battery capacity indication. IC2 is an old East German type. It is partly compatible to the UAA180 and designed to operate LED chains. The LED's show available battery capacity from green to red (high to low). Instead of having another LED at pin 10, that signal switches relay K1, witch in turn activates the siren. After all it's hard to see those cute little LED's from shore ;)
That's the DC-DC board design. I'm using Lochmaster 2.0. I think it's quite a good program especially for optimizing position of elements and board size.
Here we have the finished 9.6V to 5.0V DC-DC module.
Siren
The siren has got an old fashioned schematic. Nothing special here, though it needs a bit of playing with the dimension of some parts to get the sound right.
Once again a picture of the finished siren module plus speaker (50 ohms).
Digital Switch
This switch is supplied by Conrad Electronic, Germany. It's available as kit under number 23 47 70 and ready assembled under 23 47 37. I bought two kits for the Skipper that work just nicely.
Some Mechanical Details
Instruments
The dashboard should get some instruments. I took a mail-order catalogue and scanned pictures for several instruments that were offered. After some editing and adjusting size with Photoshop, the images were printed and laminated in plastics.
Here is the original
scan plus the picture after editing
On my little bench lathe I made three tiny rings of brass. The below schematic shows how they are designed. The scales are glued inside those rings (shown green).
Below picture shows the finished instruments in relation to a European 1 Cent coin.
Finally the instruments were being glued into tight holes of the dashboard.
More Pictures Of Details
