Getting up to date...

[Ron]

I'm fighting brain overload here.
Having converted my Cockpit CX to 2.4GHz using the same module as Alan, I'm now wondering about all the compatibility problems that might arise.
So...

Questions:

1. Will all 2.4GHz receivers work with all 2.4GHz transmitters?
(If not, why not?)

2. What is the difference between DSSS and FHSS?
Something to do with pulse lengths and framing or maybe the way the actual servo works?

3. Does a 'digital' servo just use a digital internal system to position the output shaft, rather than the older analogue system with a potentiometer as the measurement of shaft angle, or is it a different system altogether?

That's enough to be going on with :lol:

Ron

[Aidan]

Questions:

1. Will all 2.4GHz receivers work with all 2.4GHz transmitters?
(If not, why not?)

2. What is the difference between DSSS and FHSS?
Something to do with pulse lengths and framing or maybe the way the actual servo works?

3. Does a 'digital' servo just use a digital internal system to position the output shaft, rather than the older analogue system with a potentiometer as the measurement of shaft angle, or is it a different system altogether?

Hi Ron,

1. No, The various 2.4GHz systems use different methods/protocols to encode their signals. Only transmitters and receivers of the same system will be compatible. Some 3rd parties have started making receivers for existing systems developed by other companies (I think you can get a 3rd party receiver that uses Futaba's FAAST system or one that uses Spektrum's DSM2) but in general you've got to stick with the brand in your transmitter!
It's the same situation as PCM was. Everyone has their own version.

I'm afraid I don't know enough about your other 2 questions to give you a useful answer

Aidan

[Ron]

Thanks Aidan,

Had a feeling that would be the case, but only to be expected really.

Ron

[Ron]

One more thing..... (Sorry about all these questions :oops: )

When you've got a 9v Rx and are using a 14v LiPo, where do you get the Rx power from?
Usually it gets it from the ESC, so how do you connect it all up? :?

Ron

[Happy Days]

9v rx? :shock: …….have to say I’ve never heard of them.

I can only assume you’ll need a separate rx battery or get a voltage regulator and run it off the li-po

Have you got 9v servos as well??? :?:

K.

[Aidan]

One more thing..... (Sorry about all these questions :oops: )

When you've got a 9v Rx and are using a 14v LiPo, where do you get the Rx power from?
Usually it gets it from the ESC, so how do you connect it all up? :?

Ron

A lot (maybe all?) of the recent 2.4GHz systems cater for higher voltage than the typical 4 or 5 cell nickel packs. I think both Jeti and Spektrum can handle anything from about 3.5V up to 9V. This caters for those wanting to use 2s lipo or LiFe cells instead of NiCd or NiMH and you may even be okay with a single lipo cell for lightweight stuff. But...as Keith says, the servos need to be compatible with those voltages too. At the moment some are but most aren't. Typically servos are rated for 6V max.

Your 2.4GHz receiver will run on the same power supply your existing receivers did.
You can use the BEC built into the ESC if it's rated for 4s use (many ESCs are only rated for BEC up to 3s or might only manage 1 or 2 servos on 4s.). Alternatively you can use a separate BEC or put in a separate receiver pack. I think a separate receiver pack is a good idea for larger models from a safety point of view but I'd probably use the ESC or a separate BEC in the Squall. If your ESC has a BEC, like most do, and you're not going to use it, don't forget to disconnect the positive pin from the connector to the receiver!

Aidan

[Ron]

Right
Thanks all/both.

It will be a new installation in the Squall, so no existing setup.
The LiPo will be a 4s (14 volts) and I guess the ESC supplied will be OK for that.

I hadn't appreciated that ESCs have battery eliminators in them to supply the Rx etc.
The Rx I will be using is a Multiplex one, and that says:

Specification:
Servo channel count 5
Reception system 2.4 GHz FHSS (Frequency
Hopping Spread Spectrum)
Operating voltage 3.5 … 9.0 V
Power supply 4 - 5 NiXX cells, 2S LiPo / LiIo
Operating temperature range -20°C … +55°C
Dimensions (L x W x H) approx. 34 x 19.5 x 11 mm
Weight approx. 7 g

So it will only take 9v max. Hence my question.

So if I've got this right, ESCs have BECs (had to look up that term :oops: ) built in, to supply the Rx and servos.
And i have to be sure the BEC will handle the total current needed by the Rx and all the servos working at once

Or if I fit a separate Rx battery (not in the Squall) I've obviously got to disconnect the + BEC supply coming from the ESC.

Ron

[Happy Days]

Yea’ pretty much Ron. :clap:  

It’s not true to say that all ESC’s have BEC’s, but the one that comes with your Squall will, which will be more than capable of running your rx and the three servos the model will need. Even with the VT unit fitted.

That’s one of the nice things about the purchase, most the electrical equipment that’s needed is supplied with the model. (You haven’t got to figure out what will match up with what!)

You will need three servo extension leads though. (and the servos) No doubt you have some in your workshop somewhere. :wink:

Keith

[Ron]

Thanks Keith.

Yes sure there must be some servo extensions somewhere about in the mess that passes for a workshop. :oops:

Ron

[Alan_Perse]

Hi Ron.
How do you find the multiplex module. I've had a few flights with mine and it seems to work great.

[Ron]

Hi Alan,

So far so good, but as i haven't actually flown with it yet ... :oops:

The idea is excellent.
Just a bit of Velcro to hold it on the Tx, plug it in, and there you go.
No stripping the Tx apart, and just a flip of a switch to change back to 35MHz at any time.

I've only tried it on the bench and it seems to be good.
I have to say I like the idea of not having to worry about channels, and the nice short antenna for the Rx means no trailing wires, or threading it down the fuz.

And no worries about snapping the Tx antenna.

Ron