What radio gear do I need?

[alvinlwh 5888]

Another day, another round of questions from me.

This is not the usual RC question, and I suspect any tank builders will be able to answer it in a snap. I had already built the basic Arm Crawler and want to make it controllable. So I got the Twin-Motor Gearbox (two of them in fact! ) and a pair of Torque Tuned 2 130 motors (why not?). Now, I also got the Tamiya 70102 2-Channel Remote Control Box Kit on order but that is wired control and will like to make it wireless.

So what I need is "something" to control it. I do not want to run 2 ESCs, and given that these motors are rated for 3V, I think 3.7V is the max that should go through them. Even 4.8V is a risk and 2S will probably fry them (and destroy the gearbox, affect the rotation of the earth, open up a blackhole bringing aliens down on the Whitehouse, etc). So it will be best if the electronics can run on a 18650 (got plenty of those), 3 or 4S NiMHs max. It will be even better if the suggested equipment can run at 2.4V although I think that is probably going to be too low to power anything.

A bonus will be if I am able to use my own RC TX and RX and the thing can turn on the spot without forward movement (opposite movement of the tracks, not sure what is that called?). I do not want to use CH1 (L-R) for F-R control (that will be the easy way out right?), meaning I want, if I push forward with CH2, both motor will move forward. If I push right without pushing forward, left motor will move forward while right motor will move in reverse. 

I had found something called a "differential remote controller" on various China sites, complete with TX and RX+ESC combo. Is that the correct thing to use? If yes, this solution does not allow the use of my own TX and is slightly less idea.

A friend of mine told me to "just go and get an Arduino" but honestly that is beyond my understanding, so please don't go there.

I hope my post makes sense.

Finally, just to show that this build complies fully with the rules of TAMIYA Club, here are all the bits that are being used. 100% Tamiya.  

[Juggular 4961]

I'm intrigued, I might want to do something similar.  Does the gearbox fit into that chassis?  

The remote you linked seems to have two sockets.  Do they mean going forward is one channel and going reverse is another?  Is that how they calculate "4CH?"  I suppose if it works, 2CH is all you'd need, right?  

I wouldn't mind getting a cheap and true 4Ch radio set.  

On that note, I found another one.  I suppose 1.2A ESC would be fine for 3.7v application?  I don't know if it'd be better or worse. 

 

 

[alvinlwh 5888]

21 minutes ago, Juggular said:

I'm intrigued, I might want to do something similar.  Does the gearbox fit into that chassis?  

The remote you linked seems to have two sockets.  Do they mean going forward is one channel and going reverse is another?  Is that how they calculate "4CH?"  I suppose if it works, 2CH is all you'd need, right?  

I wouldn't mind getting a cheap and true 4Ch radio set.  

On that note, I found another one.  I suppose 1.2A ESC would be fine for 3.7v application?  I don't know if it'd be better or worse. 

That is the exact gearbox called for in the instructions. 

There is a newer version with 4 speed that may work, I am not sure. 

In Asia, I think they count F+R, L+R as 4ch, or at least that is how my friend count. 

I am not sure about the one you found (not sure about anything in fact!) which is why I asked here. I found another one, not sure if it will work. If I am not wrong, I am not supposed to post ebay links here, so a screenshot instead. I had seen in some description, they do have a BEC that will step up 3.7v to 5v for the Rx. 

 

[Juggular 4961]

The thing about a project like this is, that everything is uncertain. But when it works, it does feel good.  I'm going to keep an eye out on your project.  

(At the moment, I have more forgotten project than projects I remember)

 

[Nikko85 3439]

I think true tank controls would be easier myself.

Or, with a regular system.

Forward + no steering input (both motors forwards)

Right + no steering input (left track forwards, right track reverse, 180 spin)

Forward + right (only left moves, turn but not rotate on the spot)

Ideally you want a situation where you can spin on the spot, but also do a more gentle turn by just pushing forwards by hitting left or right a little to temporarily stop one of the tracks. 

[Jonathon Gillham 4605]

I have something similar, I think. A tracked chassis with 2 small 260 motors that my son built a tank body for. I used 2 cheap ESC which were rated to about 20amp and 8v i think, cost about NZD10 each.

They connected to each motor and then a channel each in the rx, but i had to make up a battery Y harness so they both use the same battery pack. You can also get battery packs cheap where you can use AA's and the more you use the faster it goes...used up to 8, hasn't broken yet.

Then a Flysky FS-i6 6 channel radio gear. I had bought this for a yacht so had it, but used 4 channels. I used the channel mixing on 2 channels so one stick controls the movemet. Up = fwd with both motors going fwd. Left or right is turn on the spot, with motos going opposite direction, and up and to one side will drive forward and turn.

The other stick controls the turret

With that one you would probably just use a motor on each stick though right so you just have fwd/rv on each side?

[alvinlwh 5888]

7 minutes ago, Nikko85 said:

I think true tank controls would be easier myself.

Or, with a regular system.

Forward + no steering input (both motors forwards)

Right + no steering input (left track forwards, right track reverse, 180 spin)

Forward + right (only left moves, turn but not rotate on the spot)

Ideally you want a situation where you can spin on the spot, but also do a more gentle turn by just pushing forwards by hitting left or right a little to temporarily stop one of the tracks. 

What you are describing, Tamiya HAD something like that in the old 27 era. The items I listed is what Google return when I search for "tank radio controller". All the seemingly related results have a common key word, "differential". 

So using that as a lead, the two I had posted seems the most likely candidate. What I need is some tanker (is that the correct word) to confirm if they are or not. 

The first one is a self contained all in one set while the second one seems to connect to a standard Rx. Again, I just need someone in the know to confirm if this is correct. 

[alvinlwh 5888]

7 minutes ago, Jonathon Gillham said:

I have something similar, I think. A tracked chassis with 2 small 260 motors that my son built a tank body for. I used 2 cheap ESC which were rated to about 20amp and 8v i think, cost about NZD10 each.

That is definitely not what I want as there is simply no room on the "thing" for 2 ESCs. 

8 x AA is 4 times more than what the 130s are rated for, I am sure that will swallow up the sun or something. 

Channel mixing is something I do not have on my TX. I am pretty sure there are some off the shelf solution that the tankers use. I had considered channel mixers but that will mean 2 ESCs, which is not what i want. 

[alvinlwh 5888]

28 minutes ago, Juggular said:

The thing about a project like this is, that everything is uncertain. But when it works, it does feel good.  I'm going to keep an eye out on your project.  

(At the moment, I have more forgotten project than projects I remember)

 

Have you considered buying the cheapest RC tank off Amazon or something and ripping it's radio gear out? I had... 

[TurnipJF 9182]

How about one of these?

Dual output ESC and tank mixer combined:

https://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=163278956177&category=182213&pm=1&ds=0&t=1568252515000&ver=0&cspheader=1

Or this one:

https://gbr.grandado.com/products/dual-way-bidirectional-brushed-esc-2s-3s-lipo-5a-esc-speed-control-for-rc-model-boat-tank-130-180-brushed-motor-spare-parts?gclid=Cj0KCQjwkIGKBhCxARIsAINMioK6Ub9I8AIZ9qRDnSpfegxr8Do26ac-FQI0lJ4FUc5PtWLdIymJ014aAp37EALw_wcB&variant=UHJvZHVjdFZhcmlhbnQ6NDA1MjQyMTI

[alvinlwh 5888]

31 minutes ago, TurnipJF said:

How about one of these?

Dual output ESC and tank mixer combined:

https://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=163278956177&category=182213&pm=1&ds=0&t=1568252515000&ver=0&cspheader=1

Or this one:

https://gbr.grandado.com/products/dual-way-bidirectional-brushed-esc-2s-3s-lipo-5a-esc-speed-control-for-rc-model-boat-tank-130-180-brushed-motor-spare-parts?gclid=Cj0KCQjwkIGKBhCxARIsAINMioK6Ub9I8AIZ9qRDnSpfegxr8Do26ac-FQI0lJ4FUc5PtWLdIymJ014aAp37EALw_wcB&variant=UHJvZHVjdFZhcmlhbnQ6NDA1MjQyMTI

Those are what I think are the correct ones, except the examples you showed are 6v/2S. I suppose I can DR the power output down IF these are my only options. 

Also, one question, only one wire to CH1? How does that work? 

Based on the two examples you showed, I think "mixed mode" is one of the key words I should be looking for. I think I am getting somewhere now. 

[TurnipJF 9182]

6 hours ago, alvinlwh said:

Also, one question, only one wire to CH1? How does that work? 

The other two wires are for power, which is already dealt with via the CH2 connection. All it needs from CH1 is the signal to tell it what command inputs you are giving it. 

[alvinlwh 5888]

3 hours ago, TurnipJF said:

The other two wires are for power, which is already dealt with via the CH2 connection. All it needs from CH1 is the signal to tell it what command inputs you are giving it. 

Brilliant! I am going to get one to try! For £10, it will not be an expensive mistake anyway. Thanks! 

[alvinlwh 5888]

Update, I am placing an order for the 1S version of this. No eBay links so just a screenshot.

Important part about the specs for this item is it has boosted BEC to power the RX, something sometimes not mentioned in other items. I am pretty sure many others works, but some sellers are terrible in putting down the required info (kind of like trying to shop for AM wheels and tyres). 

 

Once I received it and tested to verify that it works as it should, I will report in a build diary. 

[alvinlwh 5888]

On 9/15/2021 at 4:29 AM, TurnipJF said:

The other two wires are for power, which is already dealt with via the CH2 connection. All it needs from CH1 is the signal to tell it what command inputs you are giving it. 

Just received it, will be testing it out once I finished the Thunder Dragon.

Question: Where does the signal wire go into? The black, red or white pin?

[hIghQ 149]

Signal is white. Red&Black is plus and minus.