slipstick

The 3 connections are 5V power (centre wire, usually red), ground (usually black or brown) and the signal to the servo (usually white or orange). There's no signal if the Rx position is a dedicated battery socket. But the power and ground connections are the same on all Rx sockets, it doesn't matter if the power is going in (battery or BEC) or coming out (servos).

Steve

MustangMan

The black (or brown) pin is ground bus and all such pins in the receiver are bussed together. The red wire middle pin is the +power (usually 4.8 or 6 volts) and all such pins in the receiver are bussed together. Since all the power and ground pins are bussed, power can be supplied or drawn from any connector on the receiver. When you use an ESC with built-in BEC power to the receiver and servos is supplied through the throttle channel connector. The receiver takes its power from the bus. Servos also draw their power from their connector on the receiver.

The third pin (white or orange wire) on each channel is the "Signal" connection and is unique to each channel. The signal is a train of pulses. Each pulse ranges from about 1 to 2 milliseconds wide and repeat about 50 times per second. The width of the pulse indicates the desired servo position of that channel.

AEAJR

Typical set-up is a dark wire, a red wire and a light wire. This could be black, red and white, or Brown, red and yellow or some other combo.

The red wire is the + or power wire. The dark wire is the neg or neutral wire. Th power and neutral supply the power to the receiver and to the servos.

The light wire is the signal wire. This is what carries the commands to the servos. That is why most batteries have Dark and Red wires but no white.

Pilastor

Is there a best place to go to learn about synthesized receivers?

I've had some problems with a couple of Corona single conversion receivers glitching, and am trying to decide whether I merely need to go to a dual conversion or spend the couple extra bucks to avoid the crystal.

If I knew more about these synthesized receivers it would really help.

Thanks,
Jeff

flydiver

Synthesized RX are not necessarily a solution to glitching. RX selection and antenna placement are far more important. Dual conversion may help but may not.

In a nutshell, buy a decent RX, use the manufacturer's Xtal, and make sure the RX and antenna are FAR FAR away from ALL other electrical components. If you have a shortened antenna or it's bunched up in a knot in the bottom of the plane you can expect problems.

The Corona SC RX is generally well thought of. Bergs seem to have the best performance. Synthesized Coronas have less of a strong following and some folks have significant problems with them.

AEAJR

What do ou want to learn about synth receivers. Do you want to design one?


flydiver provides excellent advice.

I know nothing about Corona receivers. I am a big Hitec, Furtaba and Spektrum fan.

However I would first look at the installation to be sure that you have installed the receiver properly, that the antenna is not inside a carbon or metal fuselage, and that it is not bunched up.

Be sure the crystal brand matches the receiver and that the crystal is tight.

Be sure the battery wire is not weakened or frayed. A problem battery wire will cause behavior like a bad receiver due ot weak or failling power ot the receiver.

flydiver

If you are willing to do some reading this is a pretty good looking article on RX use and placement.
http://www.acteurope.de/RX-gb.pdf

FWIW lots of folks go off to Spectrum in an attempt to cure 'glitching'. I'm still flying 72 but a lot of my buddies have gone 2.4. It does cure some things, but it opens up it's own set of problems. I watched 2.4 planes go right on down with a puzzled and swearing pilot attached to the sticks. If you don't fly with large groups and need to watch channel conflicts it seems to work just fine.

Pilastor

Very helpful, guys. You may have found the problem.

My receiver is mounted in such a way that the aerial runs aft directly between the elevator and rudder servos and wires before exiting out the top of the fuselage.

The glitching has been so sporadic that I didn't think it might be due to a placement problem. I always suspected some transient signal interference (or standing too close to other 72 Mhz guys flying).

I'd appreciate your further thoughts!

Jeff

flydiver

2 personal experiences:

I bought a used Stryker from a guy. Up front he said it was for parts since he couldn't get 50ft. without losing signal. He lied-it was more like 20ft. The Stryker uses long servo leads. He must have replaced a servo after a crash or something as he routed the antenna wire along the whole servo extension. It made for a clean routing.
On a guess (I was pretty new at the time) I removed the electronics and did a range test with them just kind of hanging apart. Got great range. Put it back together with better antenna routing and never had a glitch, ever.

Made up a little 'parts' plane. Used a GWS 4-ch RX, with the 19" antenna. They are not known for their range but I was getting sporadic glitches inside of a 100 yards. It was worse closer and lower than up high and farther away. Moved the RX farther away from the rest of the electrics with a clean antenna routing and the glitches went away completely.

You should be able to stand shoulder to shoulder with other 72 pilots NOT on your channel and fly without issue. I have had my plane go nuts if someone with a live TX happens to pick up my plane at some distance away. This is called 'swamping'. An extremely strong improper signal is totally over riding a much weaker far away proper signal. Once I get the plane back and they move just a little away it corrects immediately. Then I can stand right next to them and we both fly our plane without a problem even though I'm on ch 28-positive and he's 29-negative.

Moxus

neighbour channels is dangerous.
we had several incidents caused by that, resulting that flying on neighbor channels is banned on our events.
there must always be at least one empty channel between channels in use.
the problem has likely been corrected on newer equipment, as these incidents were some years ago.
but still, it happened on what was at the time (and is still today?) high quality radio equipment from jr and futaba, wich is 2 very popular brands in my club.

FlyWheel

They still worked even with the 45th transmitter because #45 was a completely different brand. Hence the signal was completely different than the Spektrums.

IOW, it may just have well been a cell phone or a garage door opener as far as the planes' recievers were concerned.

Posted via Mobile Device

scott-p

should have waited till thursday to post that mr flywheel

AEAJR

How current is this and on what frequency band? 72mhz 50, 35, 27, ?

I have been flying for 8 years on 72. I also have planes on Spektrum 2.4 GHz.

Our club often hosts regional contests where we have had as many as 40 pilots on 72 mhz and we have never had any concerns about adjacent channels on 72 MHz. Of course we now see anywhere from 1/3 to 1/2 of the pilots on 2.4 GHz.

I have heard that decades ago there were concerns about this, but I am not aware that this is a current concern on 72 MHz and of course it doesn't even apply in the world of 2.4 GHz.

flydiver

To top it off as 2.4 proliferates like there can never be a problem a host of problems are cropping up. At SEFF this year if you aren't flying you are supposed to have your TX OFF unless you get a clearance to work on equipment.

mooredj

I learned this one the hard way. The Futaba FASST Receiver Antenna Leads are not insulated. Keep them away from carbon rods. I left mine "flying in the wind" and the one lead kept touching the carbon rod running to the elevator. It was not long and the plane was in the dirt. It was only a Flatout and did not require much in the way of repair but the lesson was learned. Tape over the leads with clear tape or at least make sure they can not touch anything that is an electrical conductor.

kyleservicetech

Not insulated? Is that true of all Futaba FASST receivers?

If any receiver antenna bare wire touches a metal object, or a conductive object, that can really result in a lot of electrical noise, not to mention detuning the receivers antenna itself.

As for motor interference, I had a lot of fun with this back in the mid 1980's with Astroflight 40 and 90 sized brush type motors. Took a lot of work to get rid of it.

The 2.4 Ghz radios are much less affected by any sort of electrical noise. (But, more than a few folks have been flying them with inadequate receiver DC power, and blaming the resultant crashes on the receiver.)

kyleservicetech

No matter how well designed or manufactured, any radio system can quit. They are far more reliable nowdays, than they were when my first Microavionics radio (1966) averaged about 20 flights between radio failures, and crashes.

I've noted more than a few club members flyingn IMHO with undersized receiver batteries. Just caught a club member flying a $$$$ turbine model using a 2700 Milliampere Hour "AA" size 5 cell receiver battery. (He upgraded to a high power LiFe battery for his turbine models)

Since I've personally tested maximum peak currents of FOURTEEN AMPERES pulled by my Extra 330 with its seven Hitec 645MG servos, that little battery simply was asking for a crash. Told the club member to NEVER fly that model again with that battery. (I load tested that battery at 12 Amps, it's voltage dropped instantly below 3.5 Volts DC.)

And, those modelers flying with the internal five volt DC supply pulled by the typical ESC are OK, but if you're using that 5 volt regulator on anything but a small model, you can overheat that 5 volt regulator. These devices are designed to shut down when they get to hot. And you crash. By the time you get to your model, that regulator has cooled down, and it's working again. BTW, those 5 volt regulators normally are equipped with a large heat sink, about two inches square with fins on them. No heat sinks are provided on the typical BEC for those ESCs.

On anything but a small back yard flyer, its best to use a switching type BEC such as Castle Creations 10 Amp BEC. Many other brands also exist.

mooredj

I should quantify this a little bit. Only the last inch or so is uninsulated. However, I think this is true of all the FASST receivers. It is not really a problem if you are aware of it. You just don't want to find this out on your maiden flight of say a $1000 giant scale.

kyleservicetech

I just don't understand why Futaba would strip the insulation off of their 2.4 Ghz antennas. The insulation has zero effect on the radio's range, and stripping off the insulation is an added step in the manufacturing process.

If that tip of the antenna is in fact bare wire, I'd be tempted to put a little shrink tubing over it, "Just because".

newbie 69

Thank you for the most informative clarification on radios and receivers. I enjoy the common words used for my understanding. Your understanding of newbie needs really outshine complicated setups and technical terms that could make my eyes crossed with the first sentence.

kyleservicetech

If you ever want a little more info on the batteries, radio system and servos we use in our models, take a look:

http://www.wattflyer.com/forums/showthread.php?t=45173

AEAJR

Another resource that may be helpful:

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
http://www.wattflyer.com/forums/showthread.php?t=31368

The article that begins this thread is actually a chapter out of this book.

AEAJR

How to select your first radio.
http://www.Wattflyer.com/forums/showthread.php?t=68741

ONETENOR

I asked a few days ago about converting Txs/Rxs from whatever freq. they are now 35 27 40 .6 etc to 2,4 Ghz. Only suggestion i got was but new kit. Yes that is the obvious solution but expensive. I am om pension so want to avoid undue costs hence my question. Do you have any ideas ed/ Cheers john M. ( onetenor)

kyleservicetech

Nope, converting a receiver from 72 Mhz to 2.4 Ghz is not practical or possible. It is totally different technology, like Chevys, and horses. There are aftermarket conversion kits that some modelers have been using. Don't know if I'd want to use one on an expensive model though.

But, now Spektrum has a standard 2.4 Ghz four channel receiver for $29.00. Various members of my RC club have been using these $29 receivers on their 100 MPH foamies. They've been flawless in operation.