Brown outs and Grey areas - the truth!

[Lee Burke]

Drifting off topic is often how things are discovered 

[Yorkman]

"Yorkman, The lower (‘unbendable’) part of the unit is more than likely a series resonator (coil) with a tapped series capacitor and will have no effect on the actual radiation pattern of the antenna. The effect is to make the antenna behave better than it physically is. Again this is an assumption but more or less confirmed by the diode ‘test’."

I kind of guessed that would be the case!

So-what if the upper 70mm of aerial was banana shaped? I know this is nothing to do with the original thread (well, much) but just throwing out a few ideas, wondering why, with all this technology, we still accept the 'DOD's existence?

[Tim Mackey]

Now...before I post the next test films.....let me describe a weird thing I have found. I am trying to replicate the crash scenario ( well equipment wise anyway ) that poor old Shaun had with his sea fury - my first brown out simulation tests were with a separate radio supply ( not BEC ) and a servo not ESC for throttle. In setting the rig up for these latest tests I discovered something weird and worrying. I am using a 4A BEC to power the 6100E and have the OPTO ESC plugged in to throttle channel, the BEC output ( which is set to the 5V setting ) to the battery socket, an LED voltspy in aux1, a DVM into gear ( just as an extra voltage monitor for the receivers operating voltage ) and an extension lead into elevator channel to couple up a servo or two to add a bit of load to the receiver. Below is a picture of the rather messy looking rig-up, however I assure you that all connections are soldered, and sound - I have triple checked them all. Granted, the DVMs may not be the best in the world...but they are good to a few millivolts or so. The whattmeter is inline with the 2s LiPo . This will show current flow and voltage INTO the regulator ( BEC ) A car headlamp bulb is connected via a switch to the input supply to add a load when required and run down the supply battery more quickly. The R/H yellow meter shows voltage OUT from the BEC or battery whichever I use at the time - and is also connected directly to the receivers battery socket. The next meter ( black ) shows the voltage as taken from the receiver gear socket, and the final yellow meter on the L/H side shows current flow through the receiver from the BEC output / battery. Upon connecting the supply ( 2s Lipo ) the voltage reads 7.34 and current flow "into" the regulator is 30m/a.

The regulator output measures 5.33V and 35.2 m/a flows through the receiver (with the ESC plugged in but no servos connected ) .....about as expected. Switching the supply load bulb on, shows a negligible difference in regulator output.

HOWEVER - the voltspy shows a mid green light only or worse - indicating a lowish supply voltage at the receiver - indeed the second meter ( black ) shows that the receiver has just 4.92 V across its servo pins - connecting a servo into circuit reduces this to just 4.56V and increases the current flow by 30 m/a. Servo movement increases this still further ( obviously ) - and depresses the voltage immediately so low as to cause a brown out!

I cannot understand why the voltage as measured at the receiver has dropped from a steady 5.33V to just 4.92 and then down again to 4.56 - and this further drop just from plugging in a stationary servo. A mere 35 m/a standby current should have little or no efffect on a voltage of 5.33 from a 4A capable regulator.

I then supplied the receiver directly from a 1700 mahr 4 cell NiMh battery pack - and the result was the same - a relatively huge difference in voltage supplied to that actually shown at the receiver pins. This suggests that a high impedance is being presented somewhere between the battery input connections on the receiver, and the output of this supply being presented at the pins. Plugging the supply into any other socket on the reciver makes no difference. I shall record the events above and upload the film tomorrow....meanwhile any suggestions ??

The rig used.

[Brian Parker]

Timbo,

 Only thougth at the moment regarding the integrity of the rigs connections, was the rig under full load conditions when you checked for any voltage across the connections?

 

Yorkman,

A banana shaped antenna is probably the fruit of fatality!

If a vertical antenna is other than straight then it is subject to severe loss of efficiency (electromagnetic waves, emitting at right angles, phasing etc.)

A vertical antenna is still a vertical antenna even when not vertical as long as it is straight, it is the name given to this type of antenna.

The ‘doughnut of death’ can be overstated. In non-technical terms, if you consider yourself as the receiver, looking directly at the end of the antenna you will see a small circle (the end of the antenna), i.e. very low signal strength. If you move slightly to one side you will see slightly more of the antenna, moving further to one side you see progressively more of the antenna i.e. increasing signal strength. Maximum strength when you are in line (parallel), then reducing as you move further until you are at the other end seeing a small circle again.

There is probably a small loss in signal strength with the antenna angled as shown it the photo due to its proximity to the body, then again it could increase signal strength, results are not always as expected regarding radiation and propagation to signals.

[Myron Beaumont]

Timbo  Have you done this with another ESC to see if  you get similar results ? ( or lack of should I say)

Looking at your time of posting I guess not yet  It makes me think of things not quite being what they claim to be AGAIN  Carry on the good work .I for one am impressed with your output on this & other subjects & youve certainly steepened my learning curve no end & also reinforced my scepticism somewhat .However don't get me wrong  Maybe  "we shall overcome one day"

Grumpy

Ps  can you mend a lap top for less than £250  that PC World quoted .Ie  the assistant trainee salesman /counter assistant  instantly said it needed a mother board .Guess what  ? I dont believe him ! Sorry for going off thread again

[Tim Mackey]

 Quote from Brian - "Only thought at the moment regarding the integrity of the rigs connections, was the rig under full load conditions when you checked for any voltage across the connections?"

Brian  I did show how the voltage seen varied ( as one would expect ) when load was increased from NIL to connecting a servo - to activating that servo. The issue I have is why the voltage drops so much - even with no load ( other than just the receiver itself ) it shows as 5.33V out from the regulator - which is connected directly to the receiver ( via a DMM set to current range ) yet voltage on the receiver pins is only 4.92. This is a drop of .41V  almost 8%. merely plugging in the servo drops it by 14% !!

Myron...the test was done with firstly a 4A 5V standalone BEC , then a seperate 4 cell 1700 mahr battery - the ESC plays no part in this particular experiment.

I am going to try a few different receivers and see what ifference I get. Either way... something is not right with this one - or it was too late at night.

[Myron Beaumont]

Sorry Timbo .What exactly is a "stand alone" BEC

[Tim Mackey]

Its a seperate BEC unit ( sometimes referred to as a UBEC or universal BEC ) rather than one which is an integral part of an ESC.

[Myron Beaumont]

Timbo Isn't that a contradiction of what its meant to be ,or does .Excuse my ignorance but I wonder how many folks out there get confused. I just thought that a BEC was an integral part of some circuitry / trickery to make Rx batteries redundant when using lipos. In other words "What does it eliminate?" ( if it's seperate )

I am presuming that BEC stands for "Battery Eliminating Circuitry" of course ! Have I got it all wrong I ask myself  ?

Back to being Grumpy !   (Where is the rest of my methanol ? )

[Myron Beaumont]

PS   If I'm wrong I' ll get mi coat

[Lee Burke]

I think the idea of the stand-alone BEC or UBEC is that it can be connected to the main drive power battery and regulate power to the Rx whilst remaining separate from the ESC.  Should the ESC get too hot and decide to shut down it wont affect the separate BEC.  Also, a switching UBEC can step down the voltage more efficiently ( creating less heat) than a BEC circuit in an ESC.

 Now, I stand happily to be corrected with this. 

[Myron Beaumont]

Thanks Lee .Now I think I get it ---Its in the main power lead from your lipo  --A sort of voltage reducer/ contrller/ stabiliser

[Former Member]

[This posting has been removed]

[Myron Beaumont]

Eric

Tried to do calcs for a 1/4 wave ground plane  (Tx box ! ) antenna for 2'400'000'000Hz   The only hurts I came up with are in my brain

[Lee Burke]

That's very instructive, thanks, Eric.  It's also a trifle confusing -LOL.  It makes me wonder why the best postion for the Tx antenna is not horizontal to the ground so that the beastly doughnut, small though it might be, is pointing a meter or so off the ground.  I suppose like that you'd get the plane into the donought as you tracked it in landing.

I have tried all ways that I can think of to get my 2.4Ghz receiver to suffer from the signal blackout in this doughnut, but so far have failed.  I have even, unwillingly flown over myself on occassion and still suffered none of its  effects, so maybe this area of weakened or absent signal is really very very narrow at these frequencies.

[Former Member]

[This posting has been removed]

[Tim Mackey]

Lee Burke wrote (see)

I think the idea of the stand-alone BEC or UBEC is that it can be connected to the main drive power battery and regulate power to the Rx whilst remaining separate from the ESC. Should the ESC get too hot and decide to shut down it wont affect the separate BEC. Also, a switching UBEC can step down the voltage more efficiently ( creating less heat) than a BEC circuit in an ESC.

Now, I stand happily to be corrected with this.

Pretty much - except that often a standalone BEC ( UBEC ) will allso be deployed in a model that does not have electric flight batteries - EG: IC powered or gliders - in this case the unit is wired to a seperate battery ( usually a 2s LiPo ) and then this feeds the radio gear. This also makes for far greater efficiency as the watts in to the BEC will be far less than the watts out...thereby ensuring looooong flight times.

I literally cannot remeber the last time I charged my slopers which all deploy this system.

For greater understanding, and so as not to digress too much from the thread topic - see here.

[Lee Burke]

Thanks for the clarifications Timbo and Eric.

[Brian Parker]

Guys, I’ve just scanned through the previous postings on this thread and the companion ‘I give up’ thread.

Now some observations with reference to the positioning of the 6100 receiver. The antenna will be a ½ wave dipole and the received signal capture area (provided it is not masked by carbon/metal etc or bent) can be likened to an ellipse, (this differs somewhat from transmitted signals from dipoles, see Erics posting above) the major axis being a little over the length of the total antenna (both legs and including the receiver in the middle), the minor axis being approx.80mm (I’ve used a bit of licence here). Clearer if you draw it out on a piece of paper. From this you will see that with the receiver antenna mounted across the fuselage and with the model passing in front of the transmitter (it’s antenna not pointing at the model, I hope) there is some reduction in capture area. With the receiver antenna mounted either vertical or in line with the fuselage the capture area is larger. You should be able to visualise the capture in other positions. The advantage of the 6200’s satellite receiver will be apparent.

Timbo’s 6100 great range over the sea is due to the dielectric constant conductivity of seawater. Don’t expect the same range over the ground and if the rain stops and the ground dries out expect less.

Also attenuation due to water vapour and precipitation could affect signal strength, Shaun mentions fog lifting prior to his crash. Is this the cause? (Joking! (Well half joking!)).

 

[Frank Skilbeck]

Timbo, re the voltage drop, the only thing you haven't replaced is the 6100 Rx, could you substitute that with another (35 MHz) even and see if that gives the same effect.

[Frank Skilbeck]

I just did a very quick test with my 6100 in my Fantom, using the ESC BEC (regular not switched type) and 3s 2100 mah lipo.

I plug in my Hextronic voltspy and DVM into Aux and Battery respectivelly. The DVM alternated between 4.99v and 5.00v and voltspy was on the upper good green (not perfect but good). If I waggled the servo's (only two) then volts dropped to 4.96v at the lowest and lower good green on the voltspy flickered. If I ran the motor up the output to the Rx steadied at 5.00v.

Note I think my DVM overeads by about 0.01v ever 2v, so actual readings may be about 0.05v high (no big deal).

So not sure whats happening with your set up or 6100 Rx but it doesn't seem like a 6100 Rx trait. 

[Tim Mackey]

Frank - from my earlier post

"I am going to try a few different receivers and see what difference I get.

Either way... something is not right with this one - or it was too late at night."

Now ...I seem to have tracked down the problem to a high voltage drop in the wiring / ammeter that was inline between the power source and the receiver - I have just tried plugging the power directly to the receiver ( as it would be in real lfe ) and the voltage drops only a few millivolts - thats more like it !!

I shall try a few different combinations of meters and the like tomorrow as I would still like to be able to get some visible real time data of current consumptions and voltage drops etc.

Thanks anyway Frank - sincerely - always nice to know someone else is actually following this lot and trying things also !

Incidentally, my sexy new 1010B charger has a featurre called "Foam cutting" which effectively works like an adjustable PSU ( volts and current ) and, provided it has a small load across it, the voltage output is adjustable whilst in use by 0.1V steps - so this is going to be my source for the next testing - which is -

At exactly what voltage does the AR6100 brown out - and does a low supply voltage affect sensitivity / range.

Stay tuned for the next geeky episode

[Tim Mackey]

Brian Parker wrote (see)

Guys, I’ve just scanned through the previous postings on this thread and the companion ‘I give up’ thread.

Now some observations with reference to the positioning of the 6100 receiver. The antenna will be a ½ wave dipole and the received signal capture area (provided it is not masked by carbon/metal etc or bent) can be likened to an ellipse, (this differs somewhat from transmitted signals from dipoles, see Erics posting above) the major axis being a little over the length of the total antenna (both legs and including the receiver in the middle), the minor axis being approx.80mm (I’ve used a bit of licence here). Clearer if you draw it out on a piece of paper. From this you will see that with the receiver antenna mounted across the fuselage and with the model passing in front of the transmitter (it’s antenna not pointing at the model, I hope) there is some reduction in capture area. With the receiver antenna mounted either vertical or in line with the fuselage the capture area is larger. You should be able to visualise the capture in other positions. The advantage of the 6200’s satellite receiver will be apparent.

Timbo’s 6100 great range over the sea is due to the dielectric constant conductivity of seawater. Don’t expect the same range over the ground and if the rain stops and the ground dries out expect less.

Also attenuation due to water vapour and precipitation could affect signal strength, Shaun mentions fog lifting prior to his crash. Is this the cause? (Joking! (Well half joking!)).

That is excellent info Brian...well done ! So basically speaking for best reception as the model flys across your field of view / strip position the rx aerial parallel to the fuselage sides, or vertical - and for best as it flys toward or away from you - across the fus is best ? Hope I have understood this correctly. Tomorrow or whenever... I shall definately try experimenting with the tr aerial positioning AND the Rx one too - as above.

Perhaps the best compromise of all then is vertically on the fuselage sidewall, then the only weak time is when the model is in vertical climb / dive....hmm maybe not such a good idea then

[Tim Mackey]

Incidentally Brian and others... would you mind if I plagiarized some of your information in a future article that I may write for either the mag or the forum? It really is very helpful to have a few more peoples combined knowlege, to help with my real world test results. I really feel that a definitive, clear, simple to understand, and accurate article about the installation and operation of the gear would be a great reference document for people to have, and will help to dispel the rumours and hearsay that seem to be building up around this new equipment.

[Former Member]

[This posting has been removed]