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[Kleban]

I am a novice at this hobby, having only joined this forum two days ago. What I’m searching for is a glossary of RC Model Boat components; servo, speed controller, etc.

I have used the search / advanced search facility, however I cannot find what I’m looking for. Can anyone point me in the direction as to where I can research this information?

Thanking you in advance.

[Netleyned]

http://www.modelboatmayhem.co.uk/

Kleban
Have you tried the main mayhem site as opposed to the forum
Lots of info of all sorts on the site

Yours Aye

Ned

[tigertiger]

I have found that one of the easiest things to do is ask when you have a specific question.

Sometimes the definition of a term is just more jargon. Or just leads to another question.

There are good sources for specific information in some fields, like electrics. But no in others, like 19th century ships rigging. And often terms are misused as synonyms for something they are not.

Luckily Mayhem is a good place to ask questions. And if you are lucky you will get two or three different answers to choose from

[Roadrunner]

A list of 'common Rc items'
 
Electric Motor :- converts electricity to mechanical work.

Two different types in this group.

Brushed:-- Dc (Direct Current) Motors, Commonly used in most boating & Rc car applications (2 wires)

Brushless:- Ac (Alternation Current) Motors, commonly used in many RC electric race boats, cars, Aircraft & Helicopters.(3 wires)

Electronic Speed Controller (ESC) :- A type of speed control which regulates the speed by PWM. This method of control is highly efficient and results in smooth, proportional throttle control, greater speed and longer run times.

Three types in this list:-

A mechanical ESC:- which is done via an adjustable series resistor, which in turn is controlled proportionality using a servo giving 'limited' speed control, usually speed was in 'steps' rather then a gradual increase. Used with Brushed motors only.

A Digital ESC for Brushed motors:- Modern CPU based speed controller designed to be used with brushed motors. (AC Current)

A Digital ESC for Brushless motors:- Modern CPU based speed controller designed to be used with brushless motors.(DC Current)

Servo:- A servo is a small motor that is wired to the receiver. If given instructions to do so by the transmitter, the servo moves a certain amount, which also moves the connected item control surface that is mechanically connected to it.

Two types in this list.

Analogue Servo (most commonly used servo):-  the servo motor is controlled via the circuit board (amplifier). The motor of an analog servo receives a signal from the amplifier 30 times a second or at 30Hz. This signal allows the amplifier to update the motor position.

Digital Servo ( Most recent, not common place yet) :- Digital servos use a high frequency amplifier that updates the servo motor position 300 times a second or at 300Hz. By updating the motor position more often, the digital servo can deliver full torque from the beginning of movement and increases the holding power of the servo. The quick refresh also allows the digital servo to have a tighter deadband.

Transmitters:- A hand held (generally) device that is the 'control center for your model', comes in two common formats, 'stick' Or 'steering' A basic transmiter will have 2 channels which generally controls forward & backwards motion and steering left/right.

The more channels on the Transmitter/receiver allows more more functions with in your model.

Receivers:- A small 'box' which 'receives' the signals sent by the transmitter and converts it into an electrical output to which source is plugged into that particular channel.

Both Transmitters & Recivers Come in 5 Groups

27mhz:- (crystal based) using the 27mhz Frequency , there are 6 basic frequency's within this wave and 6 further frequency's using 'split crystals' (a mix of two frequency's)

40mhz AM:- (crystal based) using the 40mhz AM frequency, (im not sure how many frequency's are in this band)

40mhz FM:- (crystal based) using the 40mhz FM frequency (im not sure how many frequency's are in this band)

35mhz:- (crystal based) using the 35mhz band, predominantly used for scale air craft only.

2.4Ghz:- No crystals needed for this type of controller as it is 'Digitally binded' at first operation to your receiver, there are no clashes of channels using this new digital system, allowing for unlimited users operating at any given time. Not functional with and craft that can be submerged, as this frequency finds it difficult to penetrate below the water surface.

Batterys:-An electrical battery is a combination of one or more electrochemical cells, used to convert stored chemical energy into electrical energy.

Several types in this group.

AA, AAA, C, D & 9v cells are most common in every day use.

Ni-Mh:- usually 7.2v in a range of 'mAh' sizes most common in basic models and rc cars.

LA (lead Acid):- Comes in a range of voltages and Ah from 2v, 6v, 12v up to 24v generally

'Lipos':- Lithium Polymer battery ( i have limited knowledge on lipos), Generally used with fast electrics / Brushless motors.
 
I think i have covered the 'basic's, i have missed out on IC engines on purpose as they are banned on the majority of lakes/ponds, i have also missed out Steam Engines as i have no clue what so ever about them.

Roadrunner

[Kleban]

Hey Roadrunner

Thanks for this. It is excellent  

May I take the liberty of suggesting that admin (Martin) or one of the Moderators take Roadrunners posting and place it in a section whereby all newbies to this hobby can see it. No doubt someone in the future will ask the same question.

NB: Maybe someone with knowledge of IC and Steam powered can add to this.

[barriew]

Road Runner

Just one error that I can see - you have the brushed and brushless motors wrong way round! Brushless uses AC, brushed uses DC

Barrie

[malcolmfrary]

Before placing it on the main site, it might be as well to correct the motor type references - Brushed are very much DC operated, Brushless are considered to be AC types.  Of course, in a model, they are supplied from a battery, which is a DC source, the ESC sorting out the required control.

[Roadrunner]

good spot guys, i could make an excuse for that mistake that it was a typo, but i won't haha im sure if i ask nicely Admin will correct the post and they can 'Sticky' it.

Please please nicely Admin Masters correct my awful blunder and sticky this thread for further refrence! 

[RaaArtyGunner]

good spot guys, i could make an excuse for that mistake that it was a typo, but i won't haha im sure if i ask nicely Admin will correct the post and they can 'Sticky' it.

Please please nicely Admin Masters correct my awful blunder and sticky this thread for further refrence! 

We in OZ know you were testing us to see if we were all awake and alert 

[Roadrunner]

 

[PMK]

Just one error that I can see - you have the brushed and brushless motors wrong way round!

...and, of course, with all respect, the somewhat misleading information with regards to the timing frequency of analogue servos.

[Roadrunner]

According to two sites the information i provided was correct, however there is a 'conflict' between brands on the Hz rating between Hitec and Futaba.
Hitec servos claim to run there analogues servos at 30Hz where as Futaba Run theres at 50Hz.

Most 'beginners' tend to go for the 'cheaper' hitec servos, but unless your running something that needs absolute precision then the Hz rating is really not any thing to worry about.

take a look at these sites.

http://www.hitecrcd.com/support/product-support/faqs/servos/general-servos/what-is-the-difference-between-an-analog-and-digital-servo.html

http://www.societyofrobots.com/actuators_servos.shtml (3/4 down the page)

http://www.futaba-rc.com/servos/digitalservos.pdf

http://www.rcgroups.com/forums/showthread.php?t=498802&highlight=digital+servo

If however the information is wrong, can you provide the right answer?

[Martin (Admin)]

       Martin    

[malcolmfrary]

According to two sites the information i provided was correct, however there is a 'conflict' between brands on the Hz rating between Hitec and Futaba.
Hitec servos claim to run there analogues servos at 30Hz where as Futaba Run theres at 50Hz.

What doesn't come through is that the frame frequency comes from the transmitter.  Within fairly broad limits, servos don't care.  Digital servos take the information from the transmitter, and generate the motor control information locally which allows the motor to drive faster and the position to be checked at shorter intervals so they get where they are going faster and stop more suddenly.  Important for flyboys, less so for us.  Normal servos just run at whatever rate the transmitter is generating and, offering power to the motor in bigger lumps, have to have a wider slowdown band to come to a more gentle stop to avoid overshooting.  Earlier ESCs used the same chip with the slowdown band set rather wider, giving proportional speed control.  The manufacturers can legitimately call their servos digital when they find an alternative to the position sensing pot (very analogue, that) and use brushless stepper motors.  That migh justify the higher price.
The older ESCs, using much the same chip as the servos, also ran at transmitter frame rate, and often caused the motor to "growl".  More modern ones just take their information from the transmitter and use that information to generate their output, including frequency, locally, as in the alleged digital servos.  Since higher frequencies are easier with smaller and lighter components, and small and light is generally seen as good when space and payload is limited, modern ESCs have a higher frequency output, causing the typical whine.

[PMK]

"If however the information is wrong, can you provide the right answer?"

I'll try.
Ever since Mathers and Spreng invented the R/C system - the system that we still use even to this day - the usual convention has always been that the servo signal pulse is refreshed at a frequency of fifty times per second (50Hz). This refresh rate is repeated over and over, which equates to a time of 20 milliseconds between each sync pulse. As you probably already know, each servo pulse can be on for as little as 1 millisecond or on for as long as 2 milliseconds. From this you might deduce that as many as 10 servos can be superimposed on the 20 millisecond framerate (10 x 2 milliseconds of servo 'on time' = 20mS). However, this is not quite the case because the logic counter in the receiver decoder circuitry requires a little time to breathe before starting the next sequence of the 50Hz frame rate. This so-called breathe time (otherwise knows as the reset period) is usually in the order of some 8 milliseconds. If you deduct 8mS from 20mS it leaves you with just 14 milliseconds. And since each servo requires a maximum of 2mS on time, you end up with a theoretical amount of 7 servos on the given 50Hz frame rate.
Mathematically, it means that those transmitters which use more than 7 servo channels would need a longer frame rate than the standard 20mS. For instance, a 10-channel Tx encoder would need 10 x 2mS pulses, plus another 8mS for the counter reset period - a total of 28 milliseconds, or approximately 35Hz.
Alternatively, some designers of, say, 10-channel radios will stay with the usual 50Hz frame rate, but resort to using a much shorter breathe time period. Some modern-day transmitters will use a reset period of just 4 or 5 milliseconds - some even less.

The link that you gave for the Hitec page is a tad confusing, because the page mentions a frame rate of 30Hz, yet if you click the link at the very top of the left-hand menu, entitled, "What signal do servos require to operate?", the information within kind of contradicts what they are saying on their previous page.

[Roadrunner]

Thats very interesting reading thanks guys for that, I guess it goes to show that even the so called 'experts' can't even get there facts right on there own website.
Like most who don't know the technicality's (like me on some areas) we have to take some of what we find as being true. Normaly in my case if i can locate information i will try to find matching info from other places before taking that to be true.

Just a shame that a lot of information that we are able to get hold of is incorrect or inaccurate. not being an electronics expert, most of my information is from trial and error over the past 15 years, research in areas i need to find out about and from the teaching of my father.

I think the best way forward is to break down the terminology here and correct any discrepancies that have occurred and have the document re-written, and extended with other area's that others know more then i do.

Im sure that this would make an excellent source of reference for everyone not just newbies to the hobby.  Im pretty sure many here have things they can add to this with ares they know more about. 

[Martin (Admin)]

WoW!  Real technical guys.... I was following it up till Malcolm said; "frame frequency"...... 

[malcolmfrary]

"frame frequency".....

Frame = Block of information, Frequency = repeated at whatever the rate is, like wot PMK said.
A typical frame would be -
1 quiet for a while,
2 first channel,
3 quiet,
4 next channel,
5 quiet,
6 repeat 4 & 5 for the rest of the channels,
7 go back to 1 until somebody switches off. 
The relatively long quiet bit in 1 tells the receiver that the next information is intended for channel 1, the short quiet bits in 3 and 5 tell the receiver to step on a channel and direct the information there.  A bit like a distributor, really.  Not really important for the user until something does not happen quite as planned.
The big problem with understanding advertising information of technical devices is that it is usually passed through the marketing division, who try to make it all sound more technical by using techno terms that they have heard, but not necessarily understood, while keeping the tech talk from the technical department under control.  Sometimes they use the correct terms.  This then becomes gospel, because "it came from the company", but this happens whether they were right or not.

[PMK]

Oops!...
The line which reads "If you deduct 8mS from 20mS it leaves you with just 14 milliseconds.", should of course read 12 milliseconds - not 14 milliseconds.

Top thanks to Tiger-Tiger for pointing out the error.

[Kleban]

Just enquiring as to what became of the idea of having a glossary of RC Model Boat Components ?

[malcolmfrary]

Perhaps it should appear in the "Technical Stuff" page on the main site.  A while back, a list of nautical terms appeared.............

[Roadrunner]

lol idk maybe i will work on a new one later this month and post it in the technical section unless Martin wants to have a stab at it?