Satellite lead for MB

[sutty]

All these little electronic projects that Raf has been building inspired me to attempt one of my own.

Well, to be fair, he did a lot more than inspire me, he pointed me in the right direction on more than one occasion, including checking out my final circuit diagram, and giving it the thumbs up.

Anyway, the project was to build a Spektrum satellite adaptor for the MicroBeast, so that on the 250 I can do away with the main receiver, and all of the wiring. I was just going to buy one, but £15 seemed an awful lot to me, particularly for what it was. It wasn't that I couldn't afford it, I mean it costs quite a lot anyway to convert to FBL, so what does another £15 matter, but it was just a matter of priciple, it felt like a rip off. That and it would be good fun to see if I could actually do it.

I got lots of ideas and tips by reading about it in the MB forum in a thread about building them. See here. You know why I am posting in here, but I will probably add a shorter version in there another time. No need for all the detail in that thread, as a lot of it is covered, but here, I thought it might be nice to pull it all together.

So the reason they aren't just a straight forward lead is that you have to provide Spektrum satellite receivers with a regulated 3.3V, and you have to be able to provide that voltage from whatever voltage is running on the MB bus, which is likely to be the voltage that you have your ESC or BEC set to, unless you are running something a little more complicated. Anyway, I am running at 6V from the ICE, so I have to get 6V down to 3.3V regulated, and pass the signal, which needs to be pulled up to 3.3V, as well as some capcitors etc to ensure a clean supply. The voltage regulator has to be able to provide 3.3V from a voltage which may come down as low as say 3.6V, so it has to be a suitable type, if I remember right I think they call it low drop out type.

Raf drew me the following, to help me get going.



Then we added some values to the components based on some advice from the developer from BeastX who posted in the other thread which I mentioned earlier and I then modified Raf's circuit to come up with this messy layout for the veroboard.

image1a.pdf

He checked it and confirmed it was okay, and so I tried to make it today.

I know I complain about my shaky hands, but boy were they ever evident in this little project. I was surprised I could even keep it on the bench sometimes. My soldering iron tip would move around by 3 or 4 millimeters, as I tried to keep it steady, and the solder would be the same, so how I ever got this to work out is a bit of a miracle. Oh, and if you're thinking 3 or 4mm doesn't sound much, that is with my hands resting on walls, and benches, and anything else I could think of to pin them down, and it is much more than the width of those bloody little tracks.

Anyway, here it is.





and here is a real one.



Not too bad in the end, although my capacitors are a little bigger than I expected, but I didn't really know what I was ordering, so that can't be helped. 25 years since I did anything like this, and judging by how hard it was, it may well be years before I try it again. If I could have kept my hands steady and not have to keep resoldering it, my solder would have been much more shiny, but this was the best I could do.

Here is the spec sheet for the voltage regulator used.

LP2950.pdf

One last thing, if you are wondering where one of the capacitors is, it never got delivered, so I will have to add it before I shrink wrap it. Won't be a problem though, as this one will be small, and I know where it will go. I'll add the picture when I get it.

Total cost for my home made version:

Burnt fingers and thumbs, eyestrain, stress, and the grand total of £30, for all the things I needed to buy, to be able to do it! Still can make a good few more with all the bits I have left over. Sadly I don't want to now, for the obvious reason that I have already done it now.

Oh, and one last thing, it only bloody well works. Varied my power supply from 3.5V to about 15V, and out from the little device came a constant 3.27V. Not sure if the error is the regulator or my meter, but it only needs to be between 3.1V and 3.3V for the receiver anyway, so even this tiny difference still has it in the required range, not that it would matter.


Cheers

Sut

[Tomstoy2]

Damn impressive. I like that a lot!

[redbird300]

Nice job Andrew, I know how hard these tiny circuits are to solder, congrats, you did great, IMHO.

And well said about the low drop voltage regulator, the normal ones won't do the job, as they need a higher input voltage to achieve a given output voltage.

I hope that after adding that last capacitor and putting that piece of shrink wrap around it, you will enjoy it a long time. It will make for a much cleaner wiring job on the heli, without that separate receiver. And you could always use the receiver for your next heli, lol.

[Tjomp]

Nice job, Sut.
While you didn´t gain anything economically by making this yourself, you can proudly say "I made this". And I bet you learned a thing or two in the progress.

[sutty]

Cheers guys. Sorry about the delay replying but I thought I'd already posted. You're right Tomas, when I get my next MB for the 250, I will get an extra little bit of pleasure when I see it flying, knowing that part of it is something I made myself. Well, I made it following Raf's instructions at least. I'll also get pleasure doing away with half of the wires, and ending up with a spare receiver, for which, as Raf pointed out, I will obviously have to buy another heli, otherwise it will just be sitting around doing nothing.

Anyway, before I do get another MB, I need to suss out what head to get for it. The guys in the MB FBL forum seem to be having a little trouble achieving the right geometry with an align head, with the stock 250 SE swash and the stock servos and arms. Of course they have all achieved it in the end, but not without having to change one or two things, so I need to read carefully what the problems have been.

What head do you have Tom, and any trouble hitting the required resolution for FBL during your set-up? I know it isn't MB, but I guess they have to have simlar mechanical attributes to be right for FBL, right?

Cheers

Sutty

[Tomstoy2]

I had no issues at all.

Indeed, the 720 made the 250 into such a performer as I always dreamed of it being.

I went with CNC head. Think it cost $30. Mikado make a very nice head for it, too.

[sutty]

Cheers Tom, but who are CNC? I can't search, because they all mention CNC.

[Tomstoy2]

Sorry, my friend, I tried to research who I got it thru, but I just don't remember. I want to say CNCHelicopters,,, think that's right.

It's not a very good head, I had to take a jewelers file to it to get it to work right, swash driver has only one arm, which doesn't really matter on that size.
Still, when I got done, and it didn't take much time, it's worked great!
Never having wrecked the 250 after going fbl I have no idea what feathering shaft it takes? Think it's just a stock Align shaft though.

MicroHeli makes a 250 head, though reported a little fragile in a crash.

[mnwizard]

Very nice work Sut! I love the projects you guys come up with!

BTW - here's a link to CNC Helicopters -

http://www.cnchelicopter.com/servlet/StoreFront

[copterboy]

+1 Jack. I love these little projects too.

Sutty, seen as your out of pocket, if I ever go FBL (I'm hoping one will be by this year or next ) I'll ask if you still have enough parts to make one and maybe I could buy the bits off you?

[sutty]

Yeah, no problem Denis. If I still have em, when you are ready, I'll post a set out to you foc.

Cheers

Sut

[exblade]

Awesome Sutty! I was wondering why those things were so expensive! More to them than a few crimped wires!

Terry

[sutty]

Ok, so having made this lead for the 250, I now need a Satellite, a MicroBeast, a Head, and whilst I'm at it I may as well try some FBL blades for the 450.

So having saved £15 by spending £30, I have now just spent nearly £300, on the other things I needed, and some that I didn't. Oh well.

Damn this is an expensive hobby.


Cheers

Sut

[Tomstoy2]

Ain't that the way it goes?

"Oh, a 250! Well, that won't cost much"! A grand later your sitting there wondering just what the hell is so f**kin cute about the damn thing!

[sutty]

Sorry to dig up the ancient past, but I made another of these little suckers this evening, and once again, it only sodding worked, . Soldering is better than the last one, and the whole thing seems nicer in general. Not that there's anything wrong with the last one. Still going strong in the 450, but the other day I needed one, and I thought, damn, I'll have to make one. So tonight I did, and do you know what, I have absolutely no idea what I made it for. I just set off doing it because I knew I needed one the other day, but I haven't got the faintest clue what I wanted it for.

Yes I have a spare MB, and now a spare sat lead adapter, and a spare sat, but what the hell was I planning for them?

A very senior moment. Still, the lead's good.

Cheers

Sutty

[Tomstoy2]

Hmmm, it's Monday so I guess the pub wasn't the issue. You're getting old, my friend!

[sutty]

Yep, not pub related, just my age. I should have photographed my effort this time, as it was much better, but I didn't, and it's all wrapped up in self healing tape now, which as you probably know is very difficult to remove, so I think I'll leave well alone.

All I can come up with is it must have been to set-up a test platform to investigate cetain MicroBeast behaviour, but I can't find any threads like that where an answer is outstanding.

Oh well, if I do need it there is a full system just sitting there. Maybe there are some settings I could choose to try it out in my P51? think I'll see if others have done that. There, I've invented something to do with it, lol.

Cheers

Sutty