Demystifying Nitro RC Electronics - Help and advice if you can please all

[RicoBanderez]

Hi all,
I'm having a bit of a hard time at the moment understanding the intricate details of the electronics. I'm new to RC and I've not bought anything yet but if possible I'd like to try to make the right purchases. I'm setting out to build a kit. I've recently purchased a Losi 8ight 4.0 kit. I'm trying to keep my total spend at £800 and I've spent half of that on the kit.

So here's my plan regarding radio kit and servos:
Absima CR3P AFHDS 2.4GHz 3 Channel Radio System w/ receiver
Savox SC-1258 Coreless Digital Servo (High Speed) - Speed (sec/60°) 6.0V: 0.08 / Torque (kg/cm) 6.0V: 12.0
Savox SC-1256 Coreless Digital Servo (High Torque) - Speed (sec/60°) 6.0V: 0.15 / Torque (Kg.cm) 6.0V: 20.0
LRP LiPo 2200 RXPack small Hump (RX only) 7.4V

So, 1st thing here is that I would like to use the battery as it's the right size for the radio tray on the TLR 8ight 4.0 so I'm not deliberating as to whether to use a regulator OR whether to spend a bit more money on servos that can handle the higher voltage.

1st question - what would the masses do? Use a regulator or upgrade servos? Are the servos I've chosen powerful / fast enough anyway or would higher toque /speed (and therefore voltage) be recommended anyway?

My comment - I'm a bit anal and using a regulator means I have to find space for something that's not been pre-allocated. it also means extra wiring, extra weight … perhaps some form of additional fixing which might make routing maintenance a bit more tricky .. BUT … I don't know and have no prior experience so wanted to know from you guys.

2nd question - I've had a look at the receiver that comes with the radio and can't see that it takes a crystal. can anyone verify for me?

3rd (and final) question - Is this combination of servo / receiver / transmitter / battery ok as a combination for my car?
My comment - I don't intend to race in competition only buzz it around my parents farm (honestly I'm buying it more for the tinkering!)

 

[HPIguy]

Ditch that unheard of radio system and if you're going to go cheap on radio gear, go with something decent like the FlySky GT-3 setup. And always, ALWAYS run a BEC setup. Castle makes a great, reliable, lightweight, affordable BEC setup to have the most insurance you can against brown outs. I had a brown out on a brand new short course truck which resulted in hitting the retaining wall hard at the end of the front straight. The crash repairs cost more than the BEC would have. And Savox makes great servos, but they are power hungry, so you'll need the BEC.

 

[olds97_lss]

Ditch that unheard of radio system and if you're going to go cheap on radio gear, go with something decent like the FlySky GT-3 setup. And always, ALWAYS run a BEC setup. Castle makes a great, reliable, lightweight, affordable BEC setup to have the most insurance you can against brown outs. I had a brown out on a brand new short course truck which resulted in hitting the retaining wall hard at the end of the front straight. The crash repairs cost more than the BEC would have. And Savox makes great servos, but they are power hungry, so you'll need the BEC.

BEC for nitro? I would think that since he's running a 2S lipo, he just needs to make sure to get a receiver that can handle 7.4V and servos that can do the same.

 

[RicoBanderez]

Hi @HPIguy and @olds97_lss
Thanks for your information so far … I've put a little chart together just to test my assumptions on the radio system. Can you both verify that this is correct for a start? Is there anything missing? I'm trying to understand down to the finest detail what makes up the radio system.
I'm looking to buy all the radio equipment towards the end of next month.
Thanks very much

 

[D3MON]

2.4ghz do not run off crystals, the ones that run off crystals are the 75mhz and 27mhz, which are more or less obsolete anymore, and you would have to look specifically for. As far as an external bec, they are quite small and usually fit into the reciever box depending on size of reciever. I've heard more reviews of the flysky g3-t than the other brand so would recommend that, there have been a few issues with the flysky being doa or certain things now working so make sure to buy new and through somewhere reliable for returns/replacements to swap out. As far as lipos I am still behind the times so can't give any input on that.

 

[RicoBanderez]

Ditch that unheard of radio system and if you're going to go cheap on radio gear, go with something decent like the FlySky GT-3 setup. And always, ALWAYS run a BEC setup. Castle makes a great, reliable, lightweight, affordable BEC setup to have the most insurance you can against brown outs. I had a brown out on a brand new short course truck which resulted in hitting the retaining wall hard at the end of the front straight. The crash repairs cost more than the BEC would have. And Savox makes great servos, but they are power hungry, so you'll need the BEC.

Hi @HPIguy - is it worth mentioning that my kit is a Nitro power kit? from the little amount of reading I've done on BEC (Battery Eliminator Circuit) as i'm not running a battery powered RC car, I'll be using a LiPO battery for the receiver and servos.
Is this understanding correct?

 

[RicoBanderez]

2.4ghz do not run off crystals, the ones that run off crystals are the 75mhz and 27mhz, which are more or less obsolete anymore, and you would have to look specifically for. As far as an external bec, they are quite small and usually fit into the reciever box depending on size of reciever. I've heard more reviews of the flysky g3-t than the other brand so would recommend that, there have been a few issues with the flysky being doa or certain things now working so make sure to buy new and through somewhere reliable for returns/replacements to swap out. As far as lipos I am still behind the times so can't give any input on that.

Thanks @D3MON
I'm feel like i'm getting there now on my understanding. I'm hoping that my little graph is accurate on how the RC system fits together.
Thanks
Rich

 

[D3MON]

Hi @HPIguy and @olds97_lss
Thanks for your information so far … I've put a little chart together just to test my assumptions on the radio system. Can you both verify that this is correct for a start? Is there anything missing? I'm trying to understand down to the finest detail what makes up the radio system.
I'm looking to buy all the radio equipment towards the end of next month.
Thanks very much

one thing about the diagram is that typically the receiver comes with its own antenna attached if it even has one, you wont have to get a seperate one. some 2.4ghz receivers dont even require use of an antenna at all. i know my tactic one doesn't. i am unfamiliar with the brand displayed so i can't say for sure with that one. everything else looks correct though! once you have it all in front of you it seems to make alot more sense when installing (did for me anyways). do keep in mind when installing that channel 1 on the receiver slot will be steering, channel 2 will be throttle.

 

[HPIguy]

BEC for nitro? I would think that since he's running a 2S lipo, he just needs to make sure to get a receiver that can handle 7.4V and servos that can do the same.

Absolutely. Ever seen a nitro rig's servos glitch while sitting still idling? The BEC will provide clean, stable power for the servos, and likely more than than the built in BEC can provide anyway.

Hi @HPIguy - is it worth mentioning that my kit is a Nitro power kit? from the little amount of reading I've done on BEC (Battery Eliminator Circuit) as i'm not running a battery powered RC car, I'll be using a LiPO battery for the receiver and servos.
Is this understanding correct?

As stated above, The BEC will provide clean, stable power for the servos, and likely more than than the built in BEC on your RX can provide anyway. They're not much more money than the capacitors many run that are labelled glitch busters intended for nitro rigs, and give you a lot more flexibility if you decide to change up your setup in the future.

 

[olds97_lss]

Absolutely. Ever seen a nitro rig's servos glitch while sitting still idling? The BEC will provide clean, stable power for the servos, and likely more than than the built in BEC can provide anyway.



As stated above, The BEC will provide clean, stable power for the servos, and likely more than than the built in BEC on your RX can provide anyway. They're not much more money than the capacitors many run that are labelled glitch busters intended for nitro rigs, and give you a lot more flexibility if you decide to change up your setup in the future.

Never heard of running a BEC with nitro before, unless your wanting to run high voltage servos with a 6V max receiver, then the BEC is there to limit voltage to the receiver only with the lipo bypassing it to the servos. But if the receiver can handle 7.4V, then it isn't needed. Unless the receiver itself can handle it, but then is limiting output to 6V with it's internal BEC. Just figured with receivers these days, if it can handle 7.4, then it would pass it on through.

Not saying your wrong or anything, just never came across it except for those scenarios.

 

[HPIguy]

Never heard of running a BEC with nitro before, unless your wanting to run high voltage servos with a 6V max receiver, then the BEC is there to limit voltage to the receiver only with the lipo bypassing it to the servos. But if the receiver can handle 7.4V, then it isn't needed. Unless the receiver itself can handle it, but then is limiting output to 6V with it's internal BEC. Just figured with receivers these days, if it can handle 7.4, then it would pass it on through.

Not saying your wrong or anything, just never came across it except for those scenarios.

It's not common for sure. But the BEC built into receivers is known to be weak, and not consistent, worse on some brands/models than others. To me it's just cheap insurance (along with a fail safe) on an expensive toy. But, as with all things, YMMV.

 

[RicoBanderez]

@HPIguy - thanks for the feedback!
I'm just trying to make my mind up on whether to go 6v or 7.4v. I'm waiting for some feedback from TLR direct and then i'll put another couple of diagrams together for my own understanding before re-posting to here to see what you all think.