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Hi
I'm ready to buy a radio and receiver and am looking the usual 2.4GHz sets, Giantcod and so on. Looking at them, some say crystal free. Does this mean some of them use crystals and some don't? If they don't use crystals how do people seperate out the channels they run on?
Thanks
Dave
hi dave
2.4 uses very similar technology to bluetooth in mobile phones, the transmitter and receiver lock togeather using a fixed frequency band this removes glitches, as the reciever will only answer to that transmitter. no crystals are used in any 2.4ghz sets. im new to robots but not rc my advice by good ie spektrum or futaba with built in model memory and mixing saves lots of time, jumping motors and small mixing units in the robot
That's correct Adam, 2.4ghz sets don't use crystals at all. This makes competitions far easier to police as there is no longer an issue with potential clashes in frequencies (big problem in ye olde days)
The problem that might arise soon is that 2.4 has only 32 channels , maybe one day we will struggle to all get one !
Means 16 machines can be activated at 1 time, as each set uses 2 channels inside the 2.4MHz band.
Not many channels left as sometimes there is daleks,rc chairs , skele etc allready running when we are arming up.
Not many channels are more than not enough.
Well then the 2.4 gig set simply won't work rather than allowing another transmitter to operate the machine. Hardly an issue as there are never more than 3 or 4 machines in the arena during competition fights and the large melees at the end of events etc are for fun anyways. The suprime lack of interference when compared to the old 40meg gear is also incredible. I never worry about having my aerials wrapped up and tucked in behind a fully enclosed metal container.
That's great thanks. We used to have a mare at Buggy meets with crystals, iffy 27meg sets lol. As I'm getting through sorting robot out its making me look at small things like this, it's not the sort of thing I want to take chances with. I'm the most inexperienced builder-of-things and have a generally ramshackle approach. But a 13kg robot at 15mph into someones shin would be a bit sore!
Featherweights have 3 kinds of allowed RX/TX systems according the FRA build rules.
40MHz Digital
459MHz Digital
2.4GHz DDS
I know what setup is the cheapest at the moment.
Is there any known record for largest amount of robots in any weight category in a single arena?
I can't think of any incident where more than 16 were involved.
So which setup is cheapest at the minute
2.4 GHz. You can have one for less than £50, delivered at the door.
Lowest I've found is £30.
http://www.hurricanemodels.co.uk/engine ... +TX+2.4ghz
http://www.ebay.co.uk/itm/OrangeRx-R610 ... 2a233991be
Alright, it's ugly & not versatile but it is safe & cheap.
There's actually about 80 channel's on the 2.4ghz band. Spektrum recommend the upto 40 TX's on and in use is acceptable - and after that it might work/it might not.
I still don't like the use of all these cheap 2.4ghz radio's for a few reason's - paying £15 for a radio that's controlling a pretty dangerous robot just doesn't sit right with me. I would recommend genuine Spektrum all the time!
One major difference between the cheap brands and Spektrum is that no one knows how any of them other than the genuine spektrum radio's search for clear frequencies before it chooses a new one. This means that when you are getting more and more radio's switched on, we have no idea if the cheap radio's are able to see them all and pick a free channel. Spektrum have spent a huge amount of time in this area and have 2 systems for jumping frequency on their newer systems whilst in use to any of the 80 free channels.
I agree Grant, but saying that i haven't seen any issues yet. The only problem i've seen is with running multiple makes/systems is, if you turn on your TX at the same time, there is a chance they can latch on to the same channel, I have seen this happen with DSM1 and DSM2 systems. Its easily resolved by just turning a TX off and on.
I would always recommend people buy Spektrum gear, even if you just buy a second hand TX of ebay and an Orange RX. The Futaba stuff seems to take along time to bind and doesn't always do it first time. I have used the Frsky hacks and modules and i rate those as well. Its like everything you get what you pay for.
Would avoid RadioLink gear for melee fights. It bound ok in Eric when there were only 2/3 other machines in the arena but for the FWs they didn't like it at all and refused to work. Not strictly speaking dangerous I suppose, but it is when you get angry at it not binding and start breaking things out of anger :lol:
Is it worth me pointing out to you, of all people, that the TX I linked to is made by Horizon Hobbies? of Spektrum ownership fame? I very much doubt it's unsafe.Quote:
Originally Posted by grant_ploughbot
Though I appreciate the anxiety of having a machine controlled by a cheaper radio kit, for me a robot is far scarier for having a cheap speed controller. I'd rather the money went to a good speedo & that TX seems a good compromise.
Well, you would. You're selling them! :lol:Quote:
Originally Posted by grant_ploughbot
I wouldn't. If I had the money I would switch to Futaba or some other brand. DSSS systems not as good as the FHSS based systems, but for robot purposes the DSM and DSM2 work all right. DSMx I have no info about but from what I am reading it hops at least more than DSM and DSM2 do.Quote:
Originally Posted by grant_ploughbot
Your misgivings on cheaper 2.4GHz brands are not completely without foundation either. But I have to say it does irk me somewhat if I get into range issues with my DX3S while a 20 pound 3 channel FS-GT3 can drive till the car is nothing but a spec on the parking lot.