CPS

Why should we tolerate the unknown cause of crash?I missed that we only need to talk about the looking or the program function of new transmitter before.Now we need to ask if it will result in unknown cause. Too many stories about the DSM of JR& Spectrum! I will look for the new DMSS system of JR and see the use experience of it,or I will change to "F" 2.4G .

onewasp

If you base your decisions on these posts you are naive.

At best, probably less than one third of these posts (not just here but on all such sites)
are even close to being correct.

Much is misunderstanding, lack of knowledge and/or expertise, (in some posts simply anger), and in more than a few cases it is outright fabrication.

Use these sites with care.
They are nothing more than comments between individuals whose credentials for the most part are unknown.

Spend your money and make your choices as you wish ....................

ira d

Even if less than 1/3 of the post about JR / Spektrum were correct I still would not trust my plane to them.

K-Bob

My Feedback: (1)

Gotta agree with this one. If only a 1/3 of a 1/3 were true, I'd be the guy pick up pieces.

onewasp

_________________________________

You've got it !!!!

If I used the number I was really thinking of it would have been too difficult for others to accept.

Have a Merry Christmas .

Zor

Hello everyone,

This post is written for the unacquainted.
Who knows already all about this electronic can skip reading.

This post is a follow up to post #210 which I repaired ealier this evening.
There was a picture posting problem dueto changes in the server(s) behaviors.
Apparently we cannot post manypictures simultaneously like we used to.

Suggest you go and have a look at post #210 .

In that post I was studying the behavior of the voltage right at the pins of the main receiver.
I was making the elevators lift the weight of the tail while the fuselage was supported at the front one inch behind the prop. The oscilloscople is showing the voltage drop at the receiver upon actuation of the servo.

Today I looked at the current circulating in a servo (DS821) and did some current measurements.
The picture attached show a current measurement of 220 miliamps as the unloaded servo is being actuated constantly at a fast rate and is in constant motion.

There is no current circulating when theservo is at rest like in neutral centered position.
There is also no current flow at maximum travel and holding there.
There is also no current flow at any intermidiate position if held steady, that is holding the transmitter stick steady anywhere between neutral and its full motion on the transmitter.

So we have current ONLY when the servo is in motion or trying to move or if a force is trying to change its position..

The current waveform is a recangular pulse triggered by the receiver signal on the signal wire.
The signal voltage is shown on the scope screens attached. (Ghee __got to post one pic at a time !!!)

I was observing the curent waveform but I cannot post pics. One hand to put load on the servo and even immobilize it, one hand to operate the transmitter stick and no hand left to trigger the camera.

Ya ___ I know __I could have put the camera on the tripod, set it up fo a 10 second delay and quickly grab the servo in one hand and grab the Tx stick with the other but I did not.

So the servo is drawing current only when in motion or trying to move or whenever it is trying to get in the position called for by the signal (command) if it is not already there.

The current waveform is identical to the command pulses as disributed by the receiver to all attahed servos or ESC.

So the measured 220 milliamps being the average current if the curent pulses means that the actual current while it is circulating is aboutas many times the peakcurrent of the pulses as there is servos or esc connected and in motion (Ya ESC do not move but do draw some current).

Immobilizing the servo (hard to hold with a 5/8 inch (16 mm) radius horn on a DS821 rated at 72 oz/in)
That is 7.2 lbs of force at 5/8" holding with fingers . . .WOW .

Anyway, jammed servo draws just a bit more than 0.7 amps (700 miliamps).
On a jammed servo the voltmeter was dropping barely down to 4.9 volts out of 5.0 .

I am estimating the current draw in constant airplane maneuvering (the transmitter stick never seem to stop moving) at about 2 to 5 amps with two servos in nearly constant motion.. It depends how long the commands are asking for servo motions and how far they have to go moving the flying control surfaces.

I am estimating that a 1100 mAh battery supplying 3.0 amps 20% of the time would last over one hour of flying time for a discharge of about 60%.

Now fellows do not trust this time figure. Figure your own or go by your experience with whatever set up you are using.

A last note here ___I often read to the effect that the servo(s) draw current somewhat propotional to the opposing forces (wind on the control suraces). I did not really notice that. It appears to me that the servos simply have full average curent when commanded to move and vaying the opposing force did not seem to change the current much but I admit that the DS821 is not easy to hold and present opposing force to its rotation. It is a powerful little son of a B. Hee Hee .

Enjoy your Xmas folks.

Zor

Will come back to post the pics.

Edited Saturday 18 Dec 2010 at 20:40 EST to remove the 3 pictures that were oversize and forcing the text to long lines that had each to be scrolled to read..
Please see the pictures in the next posting where they were posted one at a time.
Thanks de Zor

Zor

Posting pictures one at a time