Do I Need a Powerbox?
 

I have traditionally used a powerbox in my larger models and jets, in the belief that they offer:
1) The ability to mix more channels
2) Better protection from on board electrical interference
3) Voltage regulation
4) Allows the use of multiple batteries,for redundancy

Now there are radios, like the new JR12X 2.4ghz, I am wondering if the powerbox is required. These radios allow all the mixing at the transmitter end also 2.4ghz doesn't suffer from on board electrical interference, as did 35mhz radios. The voltage regulation and multiple batteries can be achieved with the use of a sensor switch, or the equivalent.
Am I alone in this thinking? It certainly makes the purchase of the latest transmitters more justifiable.

John

RE: Do I Need a Powerbox?
 

Hi John,

I guess you are missing one of the most important purpose that power management systems are designed for:

If you have long servo extensions (typically more than 60 cm) and 2 or more high power digital servos on Y connected directly to the receiver you lose signal and also lots of performance. Therefore these channels must be amplified. The extreme high amp loads may even damage the receiver.

A friend of mine just crashed a PCM fitted 1/4 scale model just becuse of this.

RE: Do I Need a Powerbox?
 

I know thats what they say, but most guys, in the UK for example, are running only powerbox sensor switches on models like the comp-arf Flash. This has high power digital servos and servo leads longer than 60cm with no problem at all. I have over 200 flights on mine. Is it such a factor running a 2.4ghz set up.

John

RE: Do I Need a Powerbox?
 

John

My rule has been over 1m ext lead I use a Powerbox unit-like the Evolution.
But you are right that the DSX12 will remove the need for a matchbox in most applications.

Sensor switch on normal size models is fine

regards

Dave

RE: Do I Need a Powerbox?
 

Are we 100% confident in the compatibility of 2.4 with the Powerbox? Put another way, is there a track record of guys using the Powerbox successfully with 2.4 in a variety of installations? I know there are issues with 2.4 and some gear sequencers and older servos and would like some assurance that the Powerbox (or SmartFly for that matter) are not affected.

Thanks,

Craig

RE: Do I Need a Powerbox?
 

Craig,

From a Powerbox Systems point of view there are no issues with any new powerbox. If you have an older unit (approx older than 18months) then it is probably wise to speak to Emmerich to get his view on whether it needs updating. Emmerich offers this free of charge which is great considering it was Futaba that pulled the rug out from under him with the super low voltage issue!

I have used a 14MZ and FASST in various models on 2.4 with no issues...

Skygate Hawk with 2 x 14ch RX on a PowerBox Royal
Turbo Raven with 8ch RX on PB Evolution
3m Extra 260 with 14ch RX on PB Competition
Boomerang XL with single 14ch RX on PB Royal
Various electrics on 4ch and 7ch RXs with no PBs

No problems on any setup. I ONLY use JR 8411, 8511 or 8711 in all these models so know these work 100%. Cannot comment on other brands/types.

Rgds,
Mark

RE: Do I Need a Powerbox?
 

Thanks for the info Mark! We had one instance in our club where a guy with a Powerbox was having some problems after switching to 2.4. It could be any number of things but it sounds like he needs to verify which version Powerbox he has.

Thanks again,

Craig

RE: Do I Need a Powerbox?
 

No issues with Spektrum or JR 2.4Ghz and Powerbox, I've been using it since November 2006

Dave Wilshere

RE: Do I Need a Powerbox?
 

From a reliability point of vieuw one should use as few as possible devices or components
in a redundant manner.
This is as far as I'm concerned the best way to evaluate what you should do.
Firstly
Radio manufacturers test their equipment using full equipped receivers with their largests
servo's (or at least they should do!!, anyway if they have any technical culture , and I
am confident they have, I believe they do).
So, if you don't use more servo's than your receiver can take, using no larger servo's than
your radio brand can provide, your ok whithout any power expander.
Usually RC manufacturers don't specify the amount and/or kind of servo's a particular receiver can
have don't they?

By the way, don't understand what the guy's above mean with "amplified". The servo signal is a digital
ground to rail voltage with a resolution of some 700 nanoseconds. Any decline in slew rate must be
corrected at the servo location. It simply cannot be done at the base of the transmission line.
Or isn't it the slew rate they mean.
Anyway, 1 meter simply isn't long anough to influence such a slow signal sufficiently important to notice.


Secondly
When you use a dual battery system to provide power redundancy, you should take care not to
overvoltage your radio components, so also DUAL regulators are mandatory (mostly to top on
6V) if your system can have the full battery voltage, only coupling diodes are needed.
One should be able to TEST both power circuits separately ( and here is a matter some
commercial expanders fail!!!!) so also dual switches are needed and a voltage monitor
NOT for eacht battery but only to monitor the receiver voltage.
You don't need a christmastree even if it has some sales aspects.
Note that diode coupled systems (most of the commercial systems are) require the separate battery's
only to have half the capacity needed because they are both in service.

In General

Avoid parallel servo's if you can but mix ( large receiver), then you don't need pulse buffering.
From battery to receiver use at least 1.5mm² wire and split it up in several standard
plugs you plug in y cables on the receiver.
Go for the heaviest RC-switches on the marked.

Look I know this is a very hot discussion and it is only possible to evaluate the pro's and the contra's after
a thorough and extensive statistical examination who is wright and who is wrong.( so individual experiences are worthless)
And by the way such an inquiry is virtual impossible and there for we are forced to electronically analyse
the situation because otherwise "safety" is more something that's between the ears than in the radio compartment.

Ground rule:more servo's than ports on the receiver need expander else not and simplicity and testability of the redundant parts