bruce88123

Having designed and built many power supplies I can agree to a point but these are NOT big capacitors. The caps in MY power supplies are @ 4 inches in diameter and @ 10 inches long. Yours are capable of filtering out a little noise and that's about it. Even Danny has said in the past that they won't do what you are saying. They're basically for filtering out noise generated in electric models by the propulsion systems, nothing more. Heck, buy a dozen, I don't care. It's your money. It'd be better spent on a decent battery pack though.

Enjoy.

jfeenin

It's not the size that matters so much anymore, well not physical size anyway. There was a time when a half farad cap would fill a truck bed, now they are about the size of a few pop bottle caps. None the less they would absolutely do much better at filtering out "noise" than delivering current but they will "help" in the latter. How much depends on how Farads of the cap and it's internal resistance. They are NOT a cure for sure and I don't even know the size of these caps so I can't even comment on how much these particular ones may or may not actually help. I am just saying that... in principle... it "should" help.

Don't get me wrong I was not trying to start an argument I am just pointing out that as far as basic electronics go I don't see how at the basic core a servo drawing a lot of current from a sudden fast movement is much different than a large motor starting up on say a floor buffer. They use caps for the latter to help keep the current up so in theory it's possible to help with a servo.

Now would the cap required to do that in reality be unrealistic to put in a plane? Maybe. I don't know any specifics about these little devices nor do I plan on buying any, all my servo slots will be full on mine so I will just have to buy a proper battery.

RaceCity

Sure would have to be a mighty low frequency for a HALF FARAD cap to be used...

As I recall, that's what these "stutter stoppers" were. A 0.5F Nichicon electrolytic cap. Lousy noise filter.

For that, a simple .01 (or so) ceramic across the brushes worked fine.

These caps worked in exactly the same way as big PS caps have always worked. To say that they don't is to dispute proven power supply design.

bruce88123

The role of a capacitor when starting a floor buffer motor.
http://everything2.com/index.pl?node...0start%20motor

RaceCity

Well I guess when we start wiring AC buffer motors to our ailerons we can all come back to this. <GGGG>

But in the DC world....where all we're doing is "filling in" that momentary dip in the rail votage by the discharge of the capacitor...

Nobody would dispute the point that relying on this alone is any sort of ideal solution. However, it does in fact point to the root issue of insufficient battery capacity for a given application. This has been discussed ad nauseum here.

We have wonderful technology in the radio, and wonderful technology available in batteries as well. When the two are brought together....things are sweet.

For everybody else who continues to pile on as many stalled servos as possible to a little NiCd pack.....all you can say is "good luck"

bruce88123

all you can say is "good luck"

Nah, I say "Don't do it"

jfeenin

Ah we agree. So here's a question which battery type, Lithium, NiCd, or NiMH is the best at being able to handle those current spikes without the voltage dips given the same mAh ratings on all three types and them being of equal quality manufacture?

bruce88123

My personal belief (best guess) is the NiCad but I am willing to admit I could be wrong. I'd suggest the battery forum http://www.rcuniverse.com/forum/forumid_84/tt.htm for this question.

RaceCity

Probably any battery would work provided it could maintain at least "X" voltage under load. Leyden Jars, Potato Batteries.....

Given the large numbers of these systems out there, and the vast majority of users who are just thrilled with the whole thing, I think this whole "lock out" issue is dramatically overstated by those few who just thrive on controversy.

My own highly unscientific experiments with low-voltage behavior of the system could never replicate the "lock out" scenario. Even at battery voltages ridiculously far below anything I'd ever attempt to fly with....the system continued to function...the servos continued to move in the commanded direction, etc. So.....my inclination is to believe my own observations which suggest that aside from a singularly defective unit, any problems people see are most likely the result of a poorly engineered electrical system in their model.

As for me and my sport planes....I simply use a low-resistance battery pack, ensure that it was properly charged, maintain clean & tight connections (as best as can be done with these types of connectors) and monitor the voltage throughout the day just as I've done for years. Works great. Can't imagine why problems would start now.

You can't engineer the abilities (or lack thereof) of the end user entirely out of the equation. This is why there are warnings on coffee cups that remind us that hot coffee **may be hot**[sm=idea.gif] Similarly....the DX-7 (and the Futaba, etc) come with a NiCd pack too. Perhaps the industry needs to warn us that we can't power a small carnival with the energy contained in that pack? I don't know.

Enough already. 2.4 works for me.

rmh

I know this will bore some of you -- but the easiest way of getting adequate power is to use a power source which has anextremely high ability to give up power under load
the easiest sources are :
A123 cells and the best ,latest NiMh.
LiIons and regs are also supposed to do this -IF the batts are big enough and the regs are of the proper type --
from a purely practical standpoint the big NiMh and the A123 bats will repeatedly produce power with minimal voltage depression - in amounts far in excess of anything the servos can dish out
no regs/caps etc., needed .
My favorite for most planesincluding 35% size - just a pair of A123 cells - they need to be recharged after power is about 75% used up but that is no big deal -just charge as you fill the fuel tank.

jfeenin

I agree but in my brief look today it seems very difficult to find anyone selling NiMH Packs any more. Where do you get yours?

onewasp

http://www.hangtimes.com/nobsbatteries.html

RaceCity

Another vote for NoBS batteries. Steve Anthony makes a mighty fine pack.

jfeenin

Excellent... Thanks for the info! I suspect he's about to get a new customer because I subscribe to the KISS principle personally. Less complexity means less that can break or cause problems and I'd prefer to be able to charge my batteries in the plane safely too. In looking at his site he has a good point about the weight too. Sure Lithiums weight less but they have more hassles associated with them and require more external equipment to monitor and regulate them and that stuff has weight too which takes away from the advantage of the lighter batteries. Not to mention NiMH and NiCd are technologies I am more familiar with in my RC stuff.

edberg

Anyone know when the 7C will be released?

bruce88123

Latest on Tower site is late October.

jfeenin

Tower Hobbies is currently listing "Late Oct" for availability I believe.