Fiber Optic servo extension

[Forgues-Research]

Hi Everyone, I would like to speak about large scale airplanes with electronic safety in mind
Some years ago, I developed Fiber Optic servo extensions for a full size airplane project I had, because the servos wouldn't work on the length of the extension that I was using, so I had to find a different way of doing it.
The Fiber Optic extensions were born, although that particular airplane never materialized. That's another story.

But after developing these extensions , a whole bunch of qualities became known.
First , of course, I could use these at up to 250 feet from the receiver if I so wished , of course we don't use such long extensions but at least I knew there was no longer any limits of the size of Giant Scale airplane I could build, but that's just the beginning.
Stay tuned for next installment and at any time if you have any questions, feel free to ask and I will do my best to answer all of them

 

[Forgues-Research]

I will be setting up a video shortly . but for now, here are a few other facts. Some years ago people started using two receivers to equalize the amperage load on large airplanes with multiple servos . Not for redundancy.
But there is a better , never plug the servos , any servos directly into the receiver. Let the servos have there own larger battery and the receiver can operate on a smaller lighter battery. How you may ask, well a few ways, one is to connect the negative of both batteries together and the positive of the smaller battery for the receiver, and the positive of the larger battery for the servos. Simple but there is a slight problem with this setup, the servos and receiver still has an electrical connection in common , the negative wire. You might ask "so what?" Here is why, if for any reason at any time, a servo goes bust, caput, it can and usually will feed back to the receiver , and guess what that does, you got it, fail safe with no chance of recovery, "crash" not good.

You need to isolate and I mean totally isolate the two batteries optically so if that servo goes bad, it might start draining the servo battery but the receiver is intact and continues working perfectly.
Another reason to optically isolate the receiver from the servos, is there is never any current spikes and receiver works at its optimum, yes better, much better, no more brown outs, no more current spikes , just clean signal.

There other reasons, for instance I am presently using a radio system with 8 channel receiver but I can get the full 16 channel by using Sbus system, yes other then Futaba has this possibility. but the problem with SBus on my 50% Dalotel or 55% Pitts special is you have 4 channels for each decoders, add another 3 decoders for the full 16 channels, all coming from a single output on the receiver with a 22 gauge wire which can support an grand maximum of 7 amps, not a good prospect. and yes I am using the full 16 channels this way on the Dalotel, Ok here is how I do it . instead of plugging servos on the Sbus decoders, I plug in the Fiber Optic encoder, draws less then 20 ma each so now you have 16 times 20 ma and you have 320 ma plus what the receiver draws lets say another 30 ma for a grand total of 350 ma. you can see why lets say 1000 ma lipo would work very well , then on the other end of the fiber optic cable, you have the decoder which draws less then 15 ma each, so you have a total of 240 ma,
Now each decoder supports a servo or many servos , I prefer to use one servo each so each servo has its own channel.
Now we come to the servo battery/batteries, this battery powers all the decoders plus all the servos used
Another tidbit , the reason most radios today are not very good at handling more then two servos on one output is simple, the signal output voltage is a bit more then 3 volts, so you can see where this would be a problem, now with Fiber Optic extensions, the decoder produces the same signal voltage you use from the servo battery, in my case 7.4 lipo,
Once I have a decent video, which I'm not very good at making I will post it here. stay tuned

 

[pawnshopmike]

 

[Forgues-Research]

Here are some photos of the components and a video will follow

 

[Forgues-Research]

Here is the video as promised,

 

[acerc]

Not trying to be rude or anything, but I don't understand what this would add that we are not already capable of doing with simpler methods. We can isolate servo power by not running it through the receiver, easily done. We can add multiple servo ports cheaply via multi port boards of which I make my own.

 

[Forgues-Research]

Not trying to be rude or anything, but I don't understand what this would add that we are not already capable of doing with simpler methods. We can isolate servo power by not running it through the receiver, easily done. We can add multiple servo ports cheaply via multi port boards of which I make my own.

If you read up, you will see I have mentioned how to run servos with there own battery, This method and the only one , is isolating optically, while the other method the negative wires of both servo and receiver battery are still connected , and when you have a physical connection, then the receiver is not protected from feedback from the servos incase something goes wrong, which like I said, failsafe kicks in and you crash.
A friend of mine did exactly what you said by having a separate battery for each the receiver and the servos, , He told me he didn't need the extra expanse of fiber optics, but rather have a super "bling" carbon spinner.
I guess you know what I'm leading at, he did have a faulty servo and it fed back to the receiver and yes fail safe, and totaled it, and yes he is now using the Fiber optics....

 

[Wacobipe]

Where do you buy the fiber optic components? I've never worked with anything like this before but it seems like a significant safety improvement.

 

[Forgues-Research]

Where do you buy the fiber optic components? I've never worked with anything like this before but it seems like a significant safety improvement.

I purchase all of the electronic components from DigiKey . I use components that are over rated for the job but safer in the mean time.

 

[Forgues-Research]

I would like to expand as to the components used for these fiber optics and how they are assembled for reliability
First, as I said earlier I use the very best of components, when a 1/4 watt component is good enough , I use 1/2 watt, things like this, the circuit boards are designed by me in house, and have them manufactured by a company in the US. Then after assembly, I test them rigorously, once I approve them , I coat them with GOOP which does not conduct electricity and keeps everything in place including the wires soldered on the boards. With the heat shrink on, I do a severe vibration test, that no airplane can ever muster even in a crash. Then and only then I'm good to go.
The US Army have been using them in 45 foot dirigibles and universities also in there large weight lifting aircraft competitions
So far, there has been Zero defects or broken down components .