RE: Power Expander or not -that's the question
 

Quick question for clarification here.. if a plane was running on a 9 channel receiver and had more than 9 servos that didn't need matchboxes (ie Hitecs), would a power expander be the best solution to allow the ganged servo's to be "Y'ed" into one channel without powering multiple servos on one receiver port? Also, I run 2.4ghz radio systems, if I used a PE, woudl there be any sense in getting the Spektrum AR9100 Power Safe receiver or would a standard Rx do just as well?

Thanks,
Todd

RE: Power Expander or not -that's the question
 

When you run out of receiver ports and still have sevos to install you have to look at other options. A bipe using an aileron servo in each wing can take advantage of a wye, as can a ganged mono wing installation if the ganged servos have been matched via perfect linkage and centering or by using a programmer, ala Hitec. Same applies to a ganged rudder installation using an SWB tray. The tray permits self corrections. After that you need to look at PE's or Matchboxes, etc., to provide the servo input ports. A PE might permit eliminating any wyes, which is always a good thing.

I don't fly 2.4 at all or follow 2.4 much at this time but what I've read and heard seems to show that the 2.4 receivers don't handle the voltage the 72mhz stuff did. They do aapear to reboot at a lower voltage than the old 72mhz stuff. 72 would dump at around 4.2v while the 2.4 seems to be around 3.6v from what I've read. If that is the case then you need a means to provide up to a couple amps to each servo aside from the throttle.

My personal outlook is that one should always obtain the best receiver they can regardless of what is used.

RE: Power Expander or not -that's the question
 

Guess is the wrong question to ask on this thread. Sorry guys I'll go over to another site to see if the guys there can answer this question

Happy New Year

RE: Power Expander or not -that's the question
 

Using a wye to drive two servos is the same with a PE or a receiver. There's no way to independantly alter centers or end points without a programmer, or to adjust subtrims. As far as system differences between S.F. and P.E. they are the same in principle.

I guess I was not able to lay it out simple enough.

RE: Power Expander or not -that's the question
 

While I agree you dont need a power expander and your set up is fine. I cant see spending $69.99 each for 3 matchboxes when you can get programmable servos.

RE: Power Expander or not -that's the question
 

I would sooner spend 69.99 x 3 on 3 matchbox's and buy good but cheaper servo's than spend 3 times as much for servo's and have to spend another 200+ on a servo programmer as well, and with a matchbox I can power each set independantly, I can still set my servo's and I am NOT limited to Hitec digi servo's. this suits me just fine

RE: Power Expander or not -that's the question
 

He implys that he has Hitec servos and that they are programmed. Yes, a PE would provide the port availability on a single channel without using wyes. The difference between the Smart Fly and the original PE is mostly price. Their are soem optional function differences. The user has to determine what they do or don't want or need. The S.F. or P.E. does not assure signal safety. That all comes from the reciever.

RE: Power Expander or not -that's the question
 

Back to the SF PE.
I looked at the Power Expander Sport Plus.

Batt share: Nice, but A123 short fails are uncommon so 2 A123 batts direct into Rx is ok for me
Dual buffered servo outputs: not needed, I have only one servo per surface on 50cc plane
Ignition cuttoff: nice but if this is the only function I need, that's expensive.
Seperate servo power bus: This one has me interested since I'm using the 6014 and it's spec-ed at 8-10A. But, if I look at the SF PE+ board, it will only accept 2 standard servo conectors for the battery source. Well, if they are rated at 4-5A each, I really don't get any better rating than the 6014 Rx, do I?

Then I looked at the Servo Power board.
They don't rate the current capacity but I can at least wire up Deans connectors.
They say you can cleanly power your servos at more than 6 volts and not burn up you Rx. As shown in the picture, I don't think that is correct. Plugging all 3 (-,+,signal) servo wires from the power board to the Rx would directly connect the Power Board bus to you Rx bus. If those 2 busses had different voltage supplies, that would be a smoking conflict. Right? So I think one of the + lead on each servo wire would have to be clipped. Anyway, I don't plan on needing / doing this so it's a "don't care"

So, given all that,and my 6014 8-10A spec, I think I'll go with the servo power board even though they don't spec it's current capacity, it's probably as good or better than the 6014.
Which brings me to my pet peve for this industry.....In general, the specifications / data sheets stink!....I feel better
comments?
Thanks
Gator

RE: Power Expander or not -that's the question
 

Your right with my set up I am married to Hitec servo's. But I feel for giant scale as far as quality and price they cant be beat. Now as far as programmers versus matchboxes I have 3 large scale planes one being a 40%. So lets look at the numbers with a $150.00 programmer I can set up as many planes as I want . My 40% alone would require 5 matchboxes if I did not use any Y's. Like I said before I have 2 planes with no PE but I do like the PE PRO because of the 2 deans inputs, failsafe switch, numerous built in filters, direct power to all servos , and filtered regulated 5v power to receiver.

Thats the great thing about our hobby. With all the advancements in electronics, servos, batteries, switches, etc. There are many quality setups we can choose based on what we already own, what servos we want to use, what budget we have.



I pulled this of Troy Built Models sight.

The JR Matchbox is easier to use than the Hitec Programmer as well, though there are other disadvantages to the JR Matchbox. The Matchbox is a bottleneck for the current to the servos. You have one plug and one wire feeding power to 2, 3 or 4 servos. This is fine with smaller models, up to 35%, but above that, it's too restrictive. Adding a separate battery is an option, but if you use 5 Matchboxes on a plane you don't want to use 5 additional batteries due to weight, cost and complexity. Also, the Matchboxes add cost and weight, while a single Hitec Programmer can be used and removed and it can be used on all your planes. This way if you sell your plane, you don't have the extra cost of the matchboxes. If you're lucky, you can borrow a programmer from a club member and it won't cost you anything to program them.

RE: Power Expander or not -that's the question
 

Now I am really curious, Why use 5 matchbox's?
I am building a 40% Edge now, and I can see no reason this side of the moon to use 5 matchbox's, 4 would be the most, and I only need 3 because I am using a seiko on the rudder,
my set up is

Ailerons 3 jr 8411 ea wing 2 matchbox's 1 4200 mah 4s A123 @6.6v
Elevator 2 Hitec 5995 ea elev 1 matchbox 1 2100 mah 2s A123 "
Rudder 1 seiko 050 1 2350 mah 3s lipo
Rx will be either 9 or 10 ch, I have several to choose from, Rx battery will be a 2s A123 pk
Ign will use a 2700 mah nicd pk


I am still trying to figure where the heck you'd need the 5th matchbox.[sm=confused.gif]

also the price of those u-beaut hitec programmable servo's? ouch [:@] I can get jr's for less than 2/3 of those Hitecs, and I am NOT too proud to say that I neither need nor can justify the digital hitecs, which while they sound nice, I wont really see any difference in flying the plane, and therefore cant justify the expense

RE: Power Expander or not -that's the question
 

I'm remaining in the corner for this part of the discussion;)

RE: Power Expander or not -that's the question
 

Ok,

I must say I'm ignorant on setting up a 40% plane. I've never owned one. But I've been flying 35%'s for several years now, and just recently got my first Smart Fly Power Expander. I jumped on the programmable Hitecs as soon as they came out, and have no regrets at all. The programmer is so sweet to use, and lets you get the most out of your servos.

With that said, how can a system utilizing five batteries be dependable, user friendly, and cost effective? Couldn't it be greatly simplified with a PE and two or three A123's? I know several guys that fly that size plane on three lith-ions and regs. Again, I'm not knocking your set-up. I always just like the KISS method if possible.......

RE: Power Expander or not -that's the question
 

36oz in batteries??
3 matches..

There is a place where a PE comes in handy and really were it shines... all of those servos can plug into a PE with 2 x A123s and be done with it.

There is no reason for all those batteries and weight.



Further more the amount you spend on match boxes could be put to a 1 time purchase of a programmer and then you can buy 7955s at $89 and forget about matchboxes forever. Then you could run a couple lipos and run everything on 7.4 and have more power.

You talk about price of the hitecs.. when they are cheaper.. 89 vs 99, have twice the torque and don't need gears replaced as often. Call me silly, but I dont see how you could go wrong.

RE: Power Expander or not -that's the question
 

I figured that was the response you would get with that set up

Oh and my bad on the matchbox count I didn't realize you could plug 4 servos int one. while were on that subject does that mean you have 4 servos in the tail powered by one jr plug. Not sure I like that.

Also would it not be better to save money on all those matchboxes, batteries, and god knows how many switches . And buy better servos. 7995s are on sale all the time for $90.00 and the gear train on those will last forever. I had 8411s in a plane for 3 years although they never failed they would get the jitters after only 40 flights I had to send them in all the time. HH would repair and send them back for nothing but it was still a hassle.

You want to save money and build a solid set up on a 40% plane here you go

first borrow a programmer
then use 7995s on ail and elev at $90.00
Seiko on rudder.
power expander pro w/ failsafe switch and 2 jr charge jacks.
2- 2100mah A123s wired with deans plug and jr plug. deans plug direct to PE and jr plugs for charging
for ignition 1- A123 into smartfly fiber optic ignition kill ( no switch )
you have one switch powering the whole plane and if you cut it, or unplug it ,or smash it with a hammer, you still have power

Now back to the original Question do I need a PE on a 35% plane. My answerer is no you dont but I would prefer it on a 40%
There are other ways that would work great in setting up a 35 to 40% plane. But as you figured out by now I dont like yours because of weight and to many added failure points. Not trying to ruffle any feathers here just trying to build a better mouse trap.

RE: Power Expander or not -that's the question
 

I dont know where you can get HS 7955 for 89, the cheapest I have been quoted in the US is 179, most of your hobby shops never even bothered to reply. Same with phone calls, as soon as they hear I am from Aust. I get passed on to some kid that knows zip. and a programmer for 249? no thnx, that leaves me stuck to using hitec digi servo's, again no thnx
as for the wieght, most of my flying will be imac, and I prefer a bit of wieght. Why all the batteries? all my issues to date other than 2.4g have been broken contacts or lousy connections on batteries, so at least this way I have some back up. I am also working with a tight budget. I have looked at a PE, but the one I have been told that I need is $479. again do I really need it? I cant see it, sounds good tho.
I have put a lot of thought and done a lot of figuring and made numerous calls to get to where I am now with what I am going to use, I also have most of the parts already, so I cant justify spending a small fortune for me just to have the latest and supposedly greatest. Ok my set up is using old world tech, so what? its all proven gear, and I already have all my servo's and matchbox's are nib, and I know this will work.

RE: Power Expander or not -that's the question
 

You have never been known for not voicing your opinion before. I would not have respond because I dont like pissing match's they make everyone look bad. But I dont want new flyer's reading that and thinking thats a good setup. Again I apologies viking please dont take it personally as my wife would say we are all just nerds flying toy planes.

RE: Power Expander or not -that's the question
 

Talk to Bill at Troy Built Models for good prices and advice. Here is a link to their servos.
http://www.troybuiltmodels.com/ns/acce/servos/hitec/

RE: Power Expander or not -that's the question
 

I called them, and got passed on to someone who didnt care what he told me, and emails went unanswered, and they werent the only ones.

RE: Power Expander or not -that's the question
 

I stayed out because I think there are valid reasons for using a PE. One of them is additional port availibility. If one had an installation that would require 4 Matchboxes or one PE, the choice becomes rather obvious. Go with the PE. If you use Hitec servos and a programmer you can eliminate a PE or Matchboxes in most cases. Well programmed and you could use a wye to pair up a couple of servos. If the linkage geometry is right there won't be a current draw problem.

Since I've been in RC for a good number of years I have quite a few Matchboxes laying around that were used one or two at a time in various planes. For me using one or four is not an issue. I'm not at all worried about the so called current "bottleneck" said to be created by using a Matchbox. In the years of using them I've never experienced it. Rarely do I use an independant battery for a Matchbox. Until you gang three or more servos through one there isn't any real need.

However, if I did not already have all the stuff a PE would be my first choice due to a lower cost. If I had a transmitter that provided mixing and trims for numeroius channels I would use up those options before looking for anything more.

People have choices so they need to explore them. What they do not need is someone telling them with a sound of authority that there is only one safe way to set up their equipment. That's been my big burr from the start of this thread. People making a statement that their way is the only way and if you do it differently you won'r be safe or could be irresponsible. Whether direct or indirect that has been implied by one or two people from the beginning of the thread.

So the way you noted is a good way, as are several other methods.

RE: Power Expander or not -that's the question
 

servo city has them for $114.99 with free shipping. http://www.servocity.com/html/hs-7955tg_servo.html

I prefer to use Troybuilt never had a problem. Not sure why you were treated that way it says they ship internationally. I would ask for Bill or Gene. Maybe you could order on line. Although if you were treated rudely you may not want to.

Maybe someone else here could recommend another source

RE: Power Expander or not -that's the question
 

Got to agree with you. good post.

RE: Power Expander or not -that's the question
 

ok one question, well 2. Is my set up workable? or will it render my aircraft dangerous to fly?

RE: Power Expander or not -that's the question
 

R U being facetious again;)

RE: Power Expander or not -that's the question
 

No I just got an email saying my Edge should NOT be allowed to fly with my projected set up

RE: Power Expander or not -that's the question
 

Too many batteries for sure. The one for the elevator Matchbox is not needed. Power through the receiver.

Don't know where or how you came up with a 4s, 4,200mAh, A123 battery. One Matchbox each wing works for the triples. Using a separate power supply for each wing is not a bad thing but what you have is seriously over done. Max at 1,100 mAh, A123 per wing, OR, a single 2,500 mAh A123 serving both Matchboxes if I was doing the same.