Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: Yanbanshee on November 26, 2017, 08:57:17 PM

Title: AM radio for brushless speed control
Post by: Yanbanshee on November 26, 2017, 08:57:17 PM
Hi all you techie wizards, can you enlighten me re the use of AM (27Mz) radio with brushless speed control. Is it necessary to have a digital signal in order to satisfy the demands of a modern electric speed controller? ie a BEC with inrunner motor etc? I am worried that the setup for the controller parameters will not work with an AM signal. Or indeed that a digital servo is not essential
Title: Re: AM radio for brushless speed control
Post by: bfgstew on November 27, 2017, 12:32:28 AM
I have run a brushless speed controller with an old Futaba 27 with and without a BEC, worked perfectly ok. Not sure about servos but would bet they will work as well.
Title: Re: AM radio for brushless speed control
Post by: roycv on November 27, 2017, 06:50:00 AM
Hi all, being a cheapskate I have been the recipient of un-wanted 27 and 40 Mhtz RC.  As I they all work well I shall stay with them, I am not being a Luddite as I have an electronics background and if it is not broke do not fix it!
 The modern servos all work on the old equipment as long as you observe the wiring of the receiver.  The much respected Fleet and the Sanwa receivers have a different servo connection wire order.  There is a thread on this else where. 
I did have some problems with a brushless esc, which did not want to set up' with a 2 channel set, it worked happily on a multi channel set and then performed OK when connected  back onto a 2 ch. set.  I had difficullty with this as well, but a forum member kindly lent me an identical esc and that was the same.
The one brushless set up I have in use seems to have lost its settings and needs to go through the multi channel setting up again.  This unit is 4 -5 years old and things may have moved on.
But while I can buy a brushed esc for a fiver and have many brushed electric motors to choose from that is where I will be.  I collect model type electric motors and like to run them rather than just look at them.  I am still looking for a Taycol Comet (red magnet, not a field coil) if anyone has one?
regards Roy
Title: Re: AM radio for brushless speed control
Post by: malcolmfrary on November 27, 2017, 10:29:36 AM
An ESC or servo doesn't care what the radio link between the transmitter and receiver is.  It only responds to the output from the receiver, and that should be the same for both.  In both cases the job of the receiver is to take signals coming from the transmitter and process them, winding up with the right signal appearing on the right set of output pins according to the generally accepted standard.  Servos and ESCs are designed to respond to that signal, and they don't care where it came from.
Some modern fully digital outfits have the same signal output, but at a higher frame rate, which older plug-ins might not cope with. 
Some newer gear might have enough built in "cleverness" to work with both or either, but might be fooled into giving unexpected outputs if the 27MHz radio picked up interference and output a spurious signal, which might create confusion.
Title: Re: AM radio for brushless speed control
Post by: JimG on November 27, 2017, 11:39:37 AM
Some of the high speed brushless ESCs were known to cause interference on radios in the MHz bands. My first 2.4GHz set was bought as the ESC in an ARTF plane was known to cause problems with a 35MHz set.
Jim
Title: Re: AM radio for brushless speed control
Post by: tizdaz on January 17, 2018, 05:22:12 PM
Main issue using AM or FM radio is interference/glitching as they have limited free channels & are shared with millions of devices on the same channel. 2.4Ghz doesn't have this problem, other benefits of 2.4 is no huge antenna, no crystals which is why most people prefer them.. However for underwater models (such as subs!) FM is the preferred choice, simply because the 2.4 digital signal can not penetrate the water surface!
Title: Re: AM radio for brushless speed control
Post by: inertia on January 17, 2018, 05:59:57 PM
they have limited free channels & are shared with millions of devices on the same channel. 2.4Ghz doesn't have this problem

I think you'll find there are many more devices which use 2G4 than there are on the old VHF bands. 2G4 does not have limitless frequencies, which is why the radio manufacturers have come up with so many different ways of frequency hopping, bandwidth spreading etc. That said, I wouldn't go back to using 27Mhz AM for any reason. Submarines are altogether a different matter.
DM
Title: Re: AM radio for brushless speed control
Post by: tizdaz on January 17, 2018, 07:04:08 PM
aye there's more devices but as you say with channel hopping the receiver will automatically try to find a free channel & will scan 100's per second, whereas AM/FM your stuck on the same freq. depending on the crystal your using. I often got interference or glitches using FM, but now with 2.4, i'm yet to experience any interference over the past few years :)
Title: Re: AM radio for brushless speed control
Post by: roycv on January 17, 2018, 07:06:35 PM
Hi as a constant user of 27 and 40 Mhtz I have not had any problems, where as I used to with 2.4 Hhz with binding, has that improved?
I have a dozen 40 and 27 Mhz Rx's and will stay with them as I have a lot of crystals as well.
regards Roy
Title: Re: AM radio for brushless speed control
Post by: McGherkin on January 17, 2018, 08:16:25 PM
To be honest, my experiences with 2.4GHz have been that it simply just works.

Meanwhile, my 40mhz FM unit that I've been using for testing the beier unit has been all over the place, making it very hard to use.
Title: Re: AM radio for brushless speed control
Post by: tizdaz on January 17, 2018, 10:55:39 PM
Hi as a constant user of 27 and 40 Mhtz I have not had any problems, where as I used to with 2.4 Hhz with binding, has that improved?
I have a dozen 40 and 27 Mhz Rx's and will stay with them as I have a lot of crystals as well.
regards Roy


Hiya, i've never had issues with binding but i do know a couple of friends over the years who had & it was always with Spektrum systems, i've always used Sanwa, but on the budget end of radio systems I have the Core Code 3 channel for my 1/6 Petrol Truck & most recently I bought this for my boating: https://www.banggood.com/Flysky-FS-i6S-2_4G-6CH-AFHDS-Transmitter-With-FS-iA6B-Receiver-p-1024018.html?rmmds=search&cur_warehouse=CN as i know flysky is a good reliable  brand as again I know quite alot of people that use them & never had any issues :)