RC Radios, Transmitters, Receivers, Servos, gyros Discussion all about rc radios, transmitters, receivers, servos, etc.

PowerBox and Pulse Amplifiers

Reply

Old 08-22-2003, 08:31 PM
  #1  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

I have been very interested in this seemingly new technology that is offered by Modellbau.

I am just looking for people who are running these systems and are currently using this technology in there aircraft.

First with the Power Box, I am trying to understand why to use one? Are the compatible with say PowerfLite Lithium Ion batteries, I know they are safe with Duralite Plus so I would imagine it would be safe with PowerfLite technologies as well.

Here is the link to which I am referring to http://www.modellbau-deutsch.com/e/h.../power_box.htm

I am attaching pictures for those not familiar with the set-up.

Any experts here please chime in and let us know your thoughts.
Shortman is offline  
Reply With Quote
Old 08-22-2003, 08:36 PM
  #2  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Here is a picture showing how the Power Box is set-up...
Attached Thumbnails Click image for larger version

Name:	103796_4746.jpg
Views:	2
Size:	54.7 KB
ID:	58465  
Shortman is offline  
Reply With Quote
Old 08-22-2003, 08:37 PM
  #3  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Here is a picture showing it installed in an aircraft...
Attached Thumbnails Click image for larger version

Name:	103798_4746.jpg
Views:	4
Size:	47.2 KB
ID:	58466  
Shortman is offline  
Reply With Quote
Old 08-22-2003, 08:39 PM
  #4  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Another example...
Attached Thumbnails Click image for larger version

Name:	103799_4746.jpg
Views:	2
Size:	47.8 KB
ID:	58467  
Shortman is offline  
Reply With Quote
Old 08-22-2003, 08:42 PM
  #5  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default The Pulse Amplifier

Here is something of very high interest to me...

here is what they say DIRECTLY from the site

Can be retrofitted in models using long servo leads
essential when 2 or more servos are connected to each control channel
for all sending and receiving systems
no servo jittering as a result of long servo leads
grid-precision trimming
up to 4 servos per control channel
servo leads up to 10 metres long can be used
weighs only 1 gram!!


Function and performance

Servos in our model aircraft are supplied via three conductors. Positive, negative and pulse. Every model-maker knows that. Most model-makers are aware of the problems involved in supplying power to long leads, powerful servos, quick-acting servos or a large number of servos. By using powerful battery packs, thick cable cross-sections etc. they ensure that an adequate supply of current is available to the servos.

The pulse performance of the receiver for the servos can, however, not be greatly influenced by powerful battery packs, battery-pack cross-overs or thick cable cross-sections. The pulse, the control information for servos, always comes from a tiny IC in the receiver, no matter what type or brand of receiver you use. The pulse output, which is normally only designed for a single servo, has a very limited range as far as the servo lead is concerned. If the lead is too long or if the pulse is distributed to several servos, interference-free operation can no longer be expected. The servo electronics is, in such cases, no longer supplied with enough "pulse information". Servo jittering and imprecise trimming are the consequences which the model-maker can easily recognize him- or herself. There may also, however, be sudden, indefinable servo deflections which are sometimes mistakenly interpreted as radio interference.

Basically, it can be said that not every servo behaves in the same way, and the receiver's pulse output may also vary greatly.

Not every case of servo jittering is, however, the result of a weak pulse. We are at your service during our business hours to answer any other questions you may have concerning this.

Pulse amplifiers should always be installed where amplification is required and where such amplification can be used to best effect. This is directly in front of any servo at the end of a long lead. There is little point in installing The Pulse Amplifier directly behind the receiver only to reduce the power of the signal by fitting a long lead to the servo! If the design of your model requires several servos per channel, you can attach up to eight (8!) servos to our pulse amplifier!

Performance
And here are some arguments which speak volumes for the efficiency of our pulse amplifiers and which are intended to assist you in deciding whether and where to install them:


suitable for all receiver systems
suitable for all sender systems
suitable for all types of servo
small and light, only 1 gram!
current consumption only 10 mAh
intelligent wiring enables them to be used as V cables (Y leads), too
no servo jittering caused by long leads
precise, grid-true trimming of all servos connected
cables up to 10 metres long can be used
control pulse sufficient for up to 8 servos per channel
longer servo life
extremely simple to fit, ready wired!
lower power consumption thanks to calmer servo operation
tried and tested over many years
patented
Shortman is offline  
Reply With Quote
Old 08-22-2003, 08:44 PM
  #6  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Here is what the Pulse Amplifier looks like...
Attached Thumbnails Click image for larger version

Name:	103802_4746.jpg
Views:	8
Size:	9.5 KB
ID:	58468  
Shortman is offline  
Reply With Quote
Old 08-22-2003, 10:35 PM
  #7  
mglavin
My Feedback: (31)
 
Join Date: Nov 2001
Location: Elverta, CA
Posts: 5,295
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Shorty

The pulse amplifier you're depicting is an in-line unit. To be used in lieu of the Power Box. Many other manufacturers offer amplified wyes and extension as well. Always when using these devices, purchase the correct unit for your type of radio system, there are significant differences.

The Power Boxes have been proven by many including several TOC of late. There are at least two manufacture's of these units and probably more. The only unit currently compatible with Li-Ion technology and or voltage is the Duralite/Power Box. Emotec also has a unit soon to be released capable of working with the high static voltage of the Lithium Ions.

Actually any of the units in use and available NOW can be used with Lithium stuff as long as your using the voltage regulators in line prior to the power box. The NEW units have implemented regulators capable of working with the higher static voltages. Thus eliminating an additional failure mode and two additional connectors...

Were installing these units in our new Extras together with some plug 'n' play interconnects installed in the fuse sides and the root of the stabs and wings. No more fussing with coupling extensions.

The nice thing about the Power Box concept is the ability to drive up to four servo with a single signal output through a power buss capable of delivering 40Amps.... In our case we have three aileron servos per wing panel and two per elevator/stab. Six extension are routed to the plug 'n' play connectors for the wings and four for the elevator/stabs. This provides a single HD 22 gage servo wire extension all the way to the servo which is optically isolated and the signal is boosted as well....

With programmable servos one could eliminate mixes which are an absolute in many cases. I'm looking forward to using these gadgets....
mglavin is offline  
Reply With Quote
Old 08-23-2003, 12:05 AM
  #8  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Mike, what would I do without you lol....

Josh was telling me about your new Extra, looks aaaaaaaaawesome!

What powerboxes are you going to use along with amplifiers? You got to keep me up to date hehe
Shortman is offline  
Reply With Quote
Old 08-23-2003, 12:31 AM
  #9  
blkbird68
Senior Member
My Feedback: (19)
 
Join Date: Apr 2002
Location: Henderson, KY
Posts: 639
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

one drawback is propagation delay going though the "amplifier" (wow its a $0.17 hex inverter) it has to go through the inverter twice adding about 3ms delay each pass through the inverter. and then you talk about a optically isolated and amplified.. the output of the opto isolator is so weak it has to be amplified.. so anytime you use opto isolation it will also have an amplified output. plus you have added even more propagation delay in the system. and the buss is good for 40 amps??? well what good is that when the connectors you are using on your batt. packs is only good for 2amps??? put about a 4 amp load on your system sometime and then measure the voltage before and after the plug on your batt.

another thing I almost forgot...when you go through the inverter, buffer amp what ever you want to call it...it chops the signal to a nice square pulse...however the pulse that it received was not perfectly square. I have found that depending on the load on the system this effects the repeatability of the resulting signal.
blkbird68 is offline  
Reply With Quote
Old 08-23-2003, 12:38 AM
  #10  
mglavin
My Feedback: (31)
 
Join Date: Nov 2001
Location: Elverta, CA
Posts: 5,295
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

No pulse amplifiers are required as the Power Boxes have them incorporated internally.

Were going to use the Model Bau Power Boxes, initially. I'll give the Emotec unit a ride when they become available in late September.

Below is a picture of the plug 'n' play connectors were using to eliminate the interconnections at the wing and stab panels.

Each servo will have its own HD wire extension, power source and signal wire all the way to the Power Box.

Each 4400mAh battery pack will have a HD 18 gage pigtail and HD power connector connected directly to the Power Box, the battery power is activated from an on-board failsafe ON switch device that is NOT in-line with the battery packs. The power from either battery can be switched on and off independently and there is also a LED indicator on the switch (one switch is used for both batteries).
mglavin is offline  
Reply With Quote
Old 08-23-2003, 12:43 AM
  #11  
blkbird68
Senior Member
My Feedback: (19)
 
Join Date: Apr 2002
Location: Henderson, KY
Posts: 639
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

I think it is time for a little redesign of the current systems by the manufactures regarding the quality and strength of the PWM signal coming out of the Rx's also I would love to see the Rx power buss that could handle at least 10 amps and then use an external power buss for applications that might see higher current levels.

one of the first things that needs to be changed if the connectors. I have a homemade power buss capable of only 0.02V drop across the buss at 20 amps and i am replacing the connectors with deans 3 pin on all the servos and leads. and going to 13AWG wire on the batt.'s with gold pin connectors capable of 20amp with little loss and heavy switches.
blkbird68 is offline  
Reply With Quote
Old 08-23-2003, 01:29 AM
  #12  
mglavin
My Feedback: (31)
 
Join Date: Nov 2001
Location: Elverta, CA
Posts: 5,295
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

I have seen several independent tests that suggested the high end RX's can easily sustain 10 amps, 20 amps intermittent and 30 amps to failure.

I concur on the OEM connectors 2 amps is typical... The power boxes use a HD Graupner power pole connector designed for the high current draw of electric aircraft and such.

13 gage wire seems a little extravagant to me, BUT what the heck. I'd venture to say 13awg wire is able to carry 23A continuously at 40C and it looks HD! This wire is typical on electric cars and boats...
mglavin is offline  
Reply With Quote
Old 08-23-2003, 01:51 AM
  #13  
blkbird68
Senior Member
My Feedback: (19)
 
Join Date: Apr 2002
Location: Henderson, KY
Posts: 639
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

13 ga because I had it handy

and the losses across the buss on the RX are enormous anything past 4 amps.

one little test I did, I took a 5 cell pack (Panasonic ultra metals) through a mpi "heavy" switch through the rx buss, through a 36" extension... at the batt. voltage was 6.65V...but at the load voltage was only 3.98V, same test with 3 amp load resulted in a voltage at the load of 4.15V
blkbird68 is offline  
Reply With Quote
Old 08-23-2003, 05:31 AM
  #14  
Lynx
Senior Member
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

You would have to have one serious aircraft setup to need that kind of hardware. The general RC'er would never need that kind of power distribution.
Lynx is offline  
Reply With Quote
Old 08-23-2003, 05:44 AM
  #15  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

This stuff just flies through my ears!
Shortman is offline  
Reply With Quote
Old 08-23-2003, 06:07 AM
  #16  
blkbird68
Senior Member
My Feedback: (19)
 
Join Date: Apr 2002
Location: Henderson, KY
Posts: 639
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

You would have to have one serious aircraft setup to need that kind of hardware. The general RC'er would never need that kind of power distribution
well I didn't make it with the idea of using it in a 40 size plane...

besides it is only 1.5" by 4" and weighs about 1.3oz...the point was to make sure all the servos actually receive the voltage they are suppose to. It is nothing more than an external power buss...not an optical isolator or anything like that.

and the 13awg on the pack was only because that is what I had at the time. but hey it shouldn't have any problems handling the loads it will see in this application.

22AWG servo wire shows very little drop over the typical distance involved in a plane until you reach the 4amp+ range. So no need to change that. but the standard connectors start dropping voltage before 2 amps and are just ridiculous above that level. true on the servos you wouldn't see those levels much at the servo but you will at the battery.
blkbird68 is offline  
Reply With Quote
Old 08-23-2003, 06:12 AM
  #17  
Shortman
Thread Starter
My Feedback: (21)
 
Shortman's Avatar
 
Join Date: Feb 2002
Location: Portland, Oregon
Posts: 5,966
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Who seems to be making the best Power Box at this time?
Shortman is offline  
Reply With Quote
Old 08-23-2003, 06:45 AM
  #18  
blkbird68
Senior Member
My Feedback: (19)
 
Join Date: Apr 2002
Location: Henderson, KY
Posts: 639
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default PowerBox and Pulse Amplifiers

Who seems to be making the best Power Box at this time?
toss up I think....I haven't used any of the boxes that you can buy...and the only one that I have seen used was the S.M Services opto isolator unit that Nelson Hobby imports... I have seen it in a couple jets. And those guys liked it. And the emotec unit seems to be very popular in Europe. The Emotec unit and the unit Mglavin is using would be for large servo load applications. I would think the Nelson opto unit would be more of a "mid" load type situation. and the power box you found looks interesting a well...in short...I think you could just pick which ever one suited you...
blkbird68 is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service