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Hadlock
Nov 9, 2004





Incoming total newbie post. I have some general questions.

I've been watching far, far too much PeterSirpol and RCTestFlight etc lately

Can someone explain how these things work exactly? I've done some servo robotics BS (tower pro sg-90s and some larger servos but I've bought more than my fair share of 10-packs of sg-90s along with servo testers) in the past so I have a little background, but I was using 2.4ghz bluetooth to control the robot not uh, traditional RC stuff.

This is what I understand:

Some sort of standard radio controller like you might see a super nerd with
Standard radio receiver to ???
Ardupilot device (Pixhawk 2.4.8?)
Some sort of motor controller
The actual motor/servo

uhh or better yet

screenshot from here:
https://www.youtube.com/watch?v=vAu6jkgACoc

(click to embiggen)


This seems deceptively simple

1. standard radio controller?
2. towerpro sg-90 or compatible
3. is this the radio reciever? radio antenna? looks like it could be gps but I doubt it
4. high amp motor controller for brushless dc motor
5. looks like a medium amp mutli-volt to 5v adapter for the pixhawk
6. pixhawk
7. piezo buzzer

If I wanted to do an RC sailboat I don't need item #4, but everything else is required/reccomended? Sailboats just use two servos, one for steering, and another to control continious rotation servo as a winch for the sail control lines.

Looks like the #1 spektrum controller starts at... $200? $230 for the dx7s? can I buy a used uh, 4 channel controller for $30? how many channels will I need, what "Standards" do these things use. It's amazing that the pixhawk costs about $35 on ebay, but a 7 channel controller which is arguably much older technology costs $200 what am I missing here? I feel like every $15 RC car has a 2 channel controller so something's up. Seems odd that the controller costs more than the rest of the hobby combined. Maybe it's just the brand.

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Corky Romanovsky
Oct 1, 2006



Soiled Meat

Hadlock posted:


1. standard radio controller?
2. towerpro sg-90 or compatible
3. is this the radio reciever? radio antenna? looks like it could be gps but I doubt it
4. high amp motor controller for brushless dc motor
5. looks like a medium amp mutli-volt to 5v adapter for the pixhawk
6. pixhawk
7. piezo buzzer

If I wanted to do an RC sailboat I don't need item #4, but everything else is required/reccomended? Sailboats just use two servos, one for steering, and another to control continious rotation servo as a winch for the sail control lines.

Looks like the #1 spektrum controller starts at... $200? $230 for the dx7s? can I buy a used uh, 4 channel controller for $30? how many channels will I need, what "Standards" do these things use. It's amazing that the pixhawk costs about $35 on ebay, but a 7 channel controller which is arguably much older technology costs $200 what am I missing here? I feel like every $15 RC car has a 2 channel controller so something's up. Seems odd that the controller costs more than the rest of the hobby combined. Maybe it's just the brand.

If you are interested in doing a wide number of things, you might want to get the latest Jumper or Radiomaster radio mentioned on the previous page or two. They have multi-protocol modules that let you bind with receiver modules of many many protocols. The benefit of this kind of transmitter is also the ability to adjust output behavior in the radio, rather than relying on controllers on the vehicle. Cheap RC toys often won't let you reverse servo travel, set midpoints and endpoints, control two or more servos in predefined concerted arrangements, etc.

That's not to say you couldn't find a cheap combo transmitter+vehicle and modify it to suit your use case.

You might be able to find something like a DXe for under $100 and have very limited programming options with it.

The neat thing about the Jumper or Radiomaster is you can find dirt cheap receivers that you wouldn't mind losing if your boat scuttles, whereas the DX7s or DXe might be very picky about binding with unlicensed Spektrum receivers.

ImplicitAssembler
Jan 24, 2013



Hadlock posted:

Incoming total newbie post. I have some general questions.

I've been watching far, far too much PeterSirpol and RCTestFlight etc lately

Can someone explain how these things work exactly? I've done some servo robotics BS (tower pro sg-90s and some larger servos but I've bought more than my fair share of 10-packs of sg-90s along with servo testers) in the past so I have a little background, but I was using 2.4ghz bluetooth to control the robot not uh, traditional RC stuff.

This is what I understand:

Some sort of standard radio controller like you might see a super nerd with
Standard radio receiver to ???
Ardupilot device (Pixhawk 2.4.8?)
Some sort of motor controller
The actual motor/servo

uhh or better yet

screenshot from here:
https://www.youtube.com/watch?v=vAu6jkgACoc

(click to embiggen)


This seems deceptively simple

1. standard radio controller?
2. towerpro sg-90 or compatible
3. is this the radio reciever? radio antenna? looks like it could be gps but I doubt it
4. high amp motor controller for brushless dc motor
5. looks like a medium amp mutli-volt to 5v adapter for the pixhawk
6. pixhawk
7. piezo buzzer

If I wanted to do an RC sailboat I don't need item #4, but everything else is required/reccomended? Sailboats just use two servos, one for steering, and another to control continious rotation servo as a winch for the sail control lines.

Looks like the #1 spektrum controller starts at... $200? $230 for the dx7s? can I buy a used uh, 4 channel controller for $30? how many channels will I need, what "Standards" do these things use. It's amazing that the pixhawk costs about $35 on ebay, but a 7 channel controller which is arguably much older technology costs $200 what am I missing here? I feel like every $15 RC car has a 2 channel controller so something's up. Seems odd that the controller costs more than the rest of the hobby combined. Maybe it's just the brand.

Don't by Spektrum. It's overpriced. Get Taranis or Jumper
Also don't buy a $35 pixhawk. If you really want an arduplane compatible controller that's reasonably cheap, get a Matek 405Wing.

If you want to learn on a budget,, check out FliteTest

https://www.youtube.com/playlist?li...w1vn-sjBGOkJFHV

Cheap foamboard plabes:

https://www.youtube.com/playlist?li...LH2Yc1UW4drIn2g

Hadlock
Nov 9, 2004





Thanks. Yeah it looks like the radiomaster TX16s is the way to go, touch screen, USB-C charging $130... sold

...does anybody still have these in stock at non-price-gouging cost? Looks like there is one guy on Amazon selling these things for $250, a couple of websites claim to have them still but when you go to checkout they say they're out of stock

Looks like ~14v lipo is about the standard? $10-20 for a battery looks about average, how much should I pay for a starter charger? I think with 2 servos and no brushless motor I probably don't need much juice, won't need to recharge it except when I go home and it's still half or three-quarters full

edit: just to clarify I am NOT doing a plane... doing a RC sailboat

also also, what is wrong with the pixhawk 2.4.8 that the rctestflight guy uses? seems like you can get an all-in package with 915mhz telemetry package for $170 or something on fleabay

Hadlock fucked around with this message at 07:39 on May 24, 2020

ImplicitAssembler
Jan 24, 2013



Ah, yeah as long as you have a way of recovering it, when(if) it fails, a $35 pixhawk should be fine. Flying things tend to fall out of the sky when that happens, but a boat should be fine.

For servosonly , you just need 2S.
I'd go 21700 format li-ions:
https://liionwholesale.com/collecti...=12667804450910
This will keep a pair of SG90s going for a couple of days and li-ions have much less tendency to catch fire and don't need baby sitting when charging, etc.

Is this for an automated project?. Or are you going to be using manual control at all times. (In which case, you don't need the Pixhawk, but a standard rc receiver will be enough).
You can also get a lot of telemetry directly to your radio.
If you are doing automated stuff, you will need:

Transmitter
Receiver
BEC/Voltage regulator
Batteries (as above)
2 servos.

Pixhawk
GPS
Telemetry radios

I would, in your application, skip the power module normally required for the pixhawk and just power it straight off the servo rail and then get a frsky voltage sensor to send the voltage to the transmitter instead. Reason being that most cheap (and a lot of expensive) power modules need 3S+ to work.

If it's non automated, then all you need is:

Transmitter
Receiver
BEC/Voltage regulator
Batteries (as above)
2 servos.

yergacheffe
Jan 22, 2007
Whaler on the moon.

The radiomaster TX16S just came out within the last month and it's been pretty hyped so I'd expect shortages for a while.

To give a little more information about what's going on in the black box that is the RC radio controller (we'll call it transmitter from now on, that's the official rc nerd term):

The modern transmitter basically has two main parts to it:

1. A computer that monitors the the position of the switches and gimbals, forms it into signal that then gets sent to...
2. A radio module that wirelessly sends the signal out to your receiver. This radio module can be internal/hard-wired or come out as a standalone module that can be swapped. Spektrum tends to hard-wire their stuff (cynic in me says for vendor lock-in reasons) and lots of newer transmitters coming out tend to have an external swappable module so you can use different radio links.

So since this is hobby stuff, there's not really any "standard" that vendors adhere to. The good news is that motors and servos basically want a PWM signal in the end, which is very simple to make and more or less universal. The bad thing is that, every part before that in the chain is a mess of competing vendor protocols that aren't compatible with each other. So your control link looks something like this:

Radio (switches/gimbals) -> Radio wireless module (nonstandard protocol that goes over the air) -> Receiver on boat/car/plane (converts the nonstandard protocol into PWM) -> Servos/motors

You mentioned controlling servos with bluetooth before, is there any particular reason you don't want to go the same route again for the boat? Two servos is a simple enough application you could hack together with whatever you had before. You'd basically replace the entire chain of stuff before servos/motors with your bluetooth link here.

Oh right, one more thing to add as an FYI: how a flight controller like the pixhawk plays into the radio link. It inserts itself in between the receiver and servos/motors:

Radio -> Radio wireless module -> Receiver -> pixhawk -> servos/motors

It's unclear to me what you're trying to do in your application so I don't know if you actually need a pixhawk or if you were just asking out of curiousity. If you're just trying to manually control a sailboat, you don't need one. If you want to do autopilot/GPS magic sort of stuff, then yeah you need one.

yergacheffe fucked around with this message at 21:10 on May 24, 2020

Sagebrush
Feb 26, 2012





Gravy Boat 2k

yergacheffe posted:

motors and servos basically want a PWM signal in the end, which

PPM

yergacheffe
Jan 22, 2007
Whaler on the moon.

I knew somebody was gonna give me a reply!!! I just wanted to keep it high level

E4C85D38
Feb 7, 2010

Doesn't that thing only
hold six rounds...?


Oscar Liang mentioned that there may be a coupon code for the TX16S from Banggood on his site sometime tonight. I'd like one myself to do general RC and amateur radio stuff, but since I got an RTF kit (Acrobee Lite) I'm holding off on that purchase.

(I am doing very slow LOS laps around the living room and hoping to god I don't manage to disintegrate this thing)

e: also for a sailboat you could just get away with the cheapest possible used 2ch from ebay. wheel for rudder, trigger for the mainsheet

E4C85D38 fucked around with this message at 23:16 on May 24, 2020

evil_bunnY
Apr 2, 2003



E4C85D38 posted:

Oscar Liang mentioned that there may be a coupon code for the TX16S from Banggood on his site sometime tonight. I'd like one myself to do general RC and amateur radio stuff, but since I got an RTF kit (Acrobee Lite) I'm holding off on that purchase.

(I am doing very slow LOS laps around the living room and hoping to god I don't manage to disintegrate this thing)

e: also for a sailboat you could just get away with the cheapest possible used 2ch from ebay. wheel for rudder, trigger for the mainsheet

That TX16s can talk to the acrobee.

Also i can't imagine sailing a boat without an easily accessible rudder trim.

Hadlock
Nov 9, 2004





Apparently there's an ardupilot sailboat module now that knows how to tack through the wind etc

Ardupilot seems to make sense to me because I think you can set max stops for things like max rotations of 360° servos etc which is important when you're using them as winches as of you over wind them you're gonna bring the rig down. People have built a complex set of switches and string linkage to get around this, but ardupilot/pixhawk puts this all in software. and also yeah well correct for a poorly mounted keel/rudder that pulls to one side. Hard to do hydrodynamic testing in a bathtub.

Trim tab is probably useful yeah

Alternative pants
Nov 2, 2009

WILL AMOUNT TO NOTHING IN LIFE.




I did an oopsie today.

https://i.imgur.com/8PxoXkH.mp4


CloFan
Nov 5, 2004







Fun Shoe

Yikes! Got insurance?

Alternative pants
Nov 2, 2009

WILL AMOUNT TO NOTHING IN LIFE.




CloFan posted:

Yikes! Got insurance?

Not on the camera. I've been dragging my feet about getting an actual GoPro sine the Hero8 came out and the Hero7 prices have been going down. This may be a good enough reason to finally pull the trigger.

I did get plenty of packs in on other quads before crashing the 5 Inch though.
https://www.youtube.com/watch?v=FWcWiK6qBkA

https://www.youtube.com/watch?v=G6ULxUB-4as
Although for some reason, my video editor hates me and wouldn't allow me to adjust the resolution after putting this together.

Alternative pants fucked around with this message at 01:05 on May 26, 2020

Ambihelical Hexnut
Aug 5, 2008


I reeeeeally haven't been flying the past 6 months, and it shows in the number of times I strike the ground unintentionally.

https://www.youtube.com/watch?v=Q0NtKfpFh1Q

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i own every Bionicle
Oct 22, 2005
cstm ttle? kthxbye


Finally did the maiden on this, after probably two hours of programming the transmitter (used the Taranis, Iíve only used it for simple stuff like quads in the past and done all my complex programming with Futaba, Hitec, or Airtronics).

Itís incredible. Launches so high, and just effortlessly climbs out of sight if you find any lift at all.

The dumb pull-spring setup has screwed up the rudder hinge a little and the aileron servos are moving around a bit I think (trim keeps changing). Gotta fix that and throw it around some more.

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