Custom RC System

[z3_2drive]

First here are the links to all the parts in the system excluding battery and project box:

*Motor controller: http://www.pololu.com/product/777

Receiver/Transmitter: http://www.rcplanet...._p/futk3100.htm

*The motor controller I linked is the heavy-duty model that I used in my models, but there is a smaller, less powerful and cheaper version too*

Ah I guess I'll link it too...

Motor Controller(smaller option): http://www.pololu.com/product/767

Now, Here is the fully explained system:

First:

• the jumble of lego wires on the left are the four wires that connect to the RC Buggy motors.
  
• the lego wire coming from the left is an extension to the servo.
  
• the red/white wires connect the controller and receiver
  
• the black and red wires connect to the port on the right, which you then plug a battery into.
  

Second: the four lego motor wires are put together into one pair, which connects to the first two ports of the controller-

Third:The red/black wires, which supply the power from the battery, connect into the 3rd and 4th port.

*(There are six ports in total, where you see the screw-heads)*

Fourth: Here is the tricky part

The servo wire is made up of four small wires. Two of these supply power, and two control the movements of the servo.

• The two that supply the power are connected to port 3 and 4, with the battery wires.
  
• The two that control movement are connected to port 5 and 6, all by themselves.
  

^^^ so the way it is seen here is:

SERVOCONTROL1--SERVOCONTROL2--SERVO/BATTERYPOWER1--SERVO/BATTERYPOWER2--MOTORCONTROL1--MOTORCONTROL2

Ok, so port 1/2 control buggy motors, port 3/4 give power to the system, port 5/6 control servo

Here it shows how 1/2 and 5/6 correspond to two channels on the receiver:

The red/white wires connect to channel 1 & 2 on the receiver:

And finally here it is all together again:

Sorry for the baby steps but I wanted to be clear. To know which wires from the servo control and give power, simply test with a multimeter and have this at your disposal:

[Boxerlego]

Wow! That is incredible motor controller there. I am very interested how the servo performed with this. Also what is the voltage your are running this at. Is there a voltage regulator for the servo here. It is amazing to see all four buggy motor running on one channel. Looks great a little expensive though but that is some serious power with this.

[z3_2drive]

Wow! That is incredible motor controller there. I am very interested how the servo performed with this. Also what is the voltage your are running this at. Is there a voltage regulator for the servo here. It is amazing to see all four buggy motor running on one channel. Looks great a little expensive though but that is some serious power with this.

Yeah the motor controller alone is about $90, and I run it at 11 volts

[clarkdef]

This is very cool, with this I am pretty sure you could make a helicopter with helium balloons to assist flight, it'd be like a hopper.

[tibivi]

Wow, i wonder what kind of future projects you have with this?

Tibivi

[ddimkin]

Hi z3_2drive and all, I would like to build a 2.4GHz remote system and I already posted on Brians topic here:

http://www.eurobricks.com/forum/index.php?showtopic=90556

later today I found this thread and I think this is easier to build although a bit more expensive. I understand the whole setup but have a few questions regarding the power supply. Soon I will have 4 L-motors and 2 servo motors (2 x 9398 sets). I use 8.4V LiIon battery to power my creations such as this one:

http://www.ebay.co.uk/itm/181296289459?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

and a DC/DC converter to increase the voltage to ~ 11V. I have two of them:

http://www.ebay.co.uk/itm/350963713406?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

and was planing to use each in combination with one V2 Lego receiver. Of course I find the above RF setup MUCH better and wonder if it will work with the regulator (or regulators), the battery I own, the 4 L-motors and 1 or 2 servos for steering??

I know Philo's page reg. motors:

http://philohome.com/motors/motorcomp.htm#Synthesis

So my qustion is will the regulator be powerful enough or should I get a bigger one:

http://www.hobbytronics.co.uk/u3v50alv-adjustable-regulator?keyword=step%20up%20regulator

I can build the setup but don't know how to calculate electrical units so I need your help.

Thanks a lot!!!

[z3_2drive]

Sorry for not being able to do this earlier, but I have results! Using an 11 volt battery, a single L motor consumes 11W (Watt=Volt x Amp) continuously - which means under high load, such as in a crawler. When stalled, it consumes 22W. So there are three main conclusions I came to.

1) You will be better off buying a 3s battery pack regardless of using RF or IR. It is more efficient and there is less risk of damaging electronics since the DC/DC converter won't be necessary anymore.

2) I like your idea and I think it will work, but you will have to test it on your own. Any electronics between the battery and the motors is at risk, such as the IR receiver and the converter. The 25W rating on your converter is the absolute maximum, so if it stalls at 22W for more than a couple seconds it could overheat the converter or it will shut itself down, but I don't know if it has this feature.

3) If you use two motors, then the power doubles, and this is where it's tricky. If it stalls, which would be 44W, the converter or IR receiver will shut down, which one will shut down first, that you will have to test. Also, high load will be 22W, so just watch for overheating.

Other info:

• These are the batteries I use in my 3s pack.
  
• If you use RF similar in capability to the one in this topic, the converter will be the weakest link. If you also buy a 3s battery, then all of the risks stated above will be avoided, and the strength of the model/the motors themselves will be the limit.
  

Edited August 7, 2014 by z3_2drive

[_Cookie_]

Hello

a single L motor consumes 11W (Watt=Volt x Amp) continuously

On the lego page it says the L Motor should max. use 450mA continuous. So the regular consumption is 9V * 0,45A = 4,05W

http://powerfunction...ault.aspx#88003

Sure, you can get a bit more out of it, but 11W... ~170% more is a bit... "life shortening" :D (just my guess)

Cookie

Edited August 7, 2014 by _Cookie_

[z3_2drive]

Well you have to remember that by continuous I meant under high load, when I was forcing my hand on a wheel to slow down the motor significantly, and in a crawler like he has in mind, the motors will be geared down, so it will be harder to even reach this load, such as climbing a hill or obstacle that's so steep that is slows the vehicle to a near stop for no more than 10 seconds, generally less. Of course driving around with the motors regularly under high load is life-shortening, regardless of the voltage

[ddimkin]

Hi and thanks for the replies and recommendations :) With "life-shortening" you probably mean the battery - is that correct? As I said above I am not very familiar with electrical terms so I guess draining more current from the battery quicker shorten its life but I have no idea how much.

And yes - the crawler is quite geared-down so motors are never under highest load. The converter has a protection but it never kicked in.

After all I decided to go with the setup from 2nd post here:

http://www.eurobrick...opic=89651&st=0

Today I ordered more powerful voltage regulators:

http://www.ebay.co.u...984.m1497.l2649

together with hobby RC components such as 3 channel transmitter, a speed controller and receiver. I am also planing to buy two buggy motors since they have a huge torque and RPM. I was thinking I can use them on a crawler too - with the speed controller I should be able to crawl real slow by having the same torque (if I am not mistaking something) and be fast on flat surfices. Is that correct? Unfortunately I won't be using 100% Lego components since I will use regular hobby-servos for steering but also now my setup is not 100% Lego.

What do you think?

Thank you!!

Edited August 7, 2014 by ddimkin

[z3_2drive]

That should work perfectly! I wish you luck. And by shortening life, I mean the motors, the battery will be unaffected, don't worry As for using two buggy motors on a crawler, in order to get good torque you will need to gear it down significantly, but after the the driveshaft, to avoid breaking u-joints. Keep us updated on whatever MOC you plan to build and I'll be glad to help since it's hard to explain with words.

[ddimkin]

Yo!! I think this should work great too I just bought 3 x servos and 2 x buggy motors.. so I'll probably gear it down and build gearboxes on front and rear axle which I will control on the 3rd channel, something like TURBO. Or at least build a fast-car with buggy motors and a crawler with L-motors. For sure I will keep you updated!

Thanks a lot!!

[z3_2drive]

This should give you some inspiration:

AndyCW's MOCs are brilliant!

[ddimkin]

Fantastic!!!!!!!!! Thanks a lot!!!!!! I should be having all parts to build something similar soon... let's see take care, man!!!

[ddimkin]

Hi z3_2drive, one more question though - have you tried a gearbox on the fast-car? Would something like this here:

be capable of shifting on the high RPMs the buggy-motors deliver? E.g. first gear 12x20 and second gear 20x12? Or accelerate the car on 1st gear then release the gas shortly then shift on 2nd gear and press gas again - all this done with the trigger and the 3rd channel button on the 2.4Ghz transmitter.

If that doesn't work - is there any other type of simple 2 gears transmission that would work?

Thanks a lot!!

[ddimkin]

I think after some more searching I found a better integrated solution that might work for me:

http://sariel.pl/201...utput-selector/

was posted here:

http://www.eurobrick...showtopic=76395

but would it work on higher speeds?!?! I mean if the vehicle is not geared down further after the gearbox like a crawler probably is.. and I am intending to build a fast car like yours

Edited August 13, 2014 by ddimkin

[z3_2drive]

That's something you have to test! Personally I have not used gearboxes in high speed vehicles, but I think with simple 2-3 speeds without a clutch, you should let off the throttle and shift. Piterx's gearboxes run really smoothly, but I don't know if he has tested them with buggy motors. All I can say is go for it and try it!

[ddimkin]

Thanks a lot!! I will test it for sure and also check Piterx's gearboxes.

[ddimkin]

Hi again z3_2drive!

Just a short question - do the buggy motors have a thermal protection? I build a testing model with two motors and connect them directly to a 8.4v battery using this type of speed contoller (not using the DC/DC convertor):

http://www.nenovtech...ml#!prettyPhoto

after a few dosens of meters motors kind of stop and when I lift the model they run again.. after a few seconds the model runs again for the same period of time :( which is basicaly 15sec or so..

I am using this battery:

http://www.ebay.co.u...984.m1423.l2649

trying to find out what kind of protection is kicking in.

Thanks very very much!!!

Edited August 24, 2014 by ddimkin

[_Cookie_]

Hi again z3_2drive!

Just a short question - do the buggy motors have a thermal protection? I build a testing model with two motors and connect them directly to a 8.4v battery using this type of speed contoller (not using the DC/DC convertor):

http://www.nenovtech...ml#!prettyPhoto

after a few dosens of meters motors kind of stop and when I lift the model they run again.. after a few seconds the model runs again for the same period of time :( which is basicaly 15sec or so..

I am using this battery:

http://www.ebay.co.u...984.m1423.l2649

trying to find out what kind of protection is kicking in.

Thanks very very much!!!

Hi,

google translator tells me that your speed-controller has a voltage protection. That means it throttles the motor down, to prevent damage to the accumulator (deep discharge).

Since you use a Li-ion pack you should set the mode of your speed-controller to Li-ion/LiPo. Especially rc car speed-controller sometimes have the NiMh/NiCd as default.

Look in the manual to change it.

But somehow i don't believe that this is the problem since the voltages aren't that much different (2s Li-ion vs 6 cell NiMh). It's worth a try :D

Cookie

[ddimkin]

Thanks a lot!!! Checking if it is the controller of the battery pack. Seems that this pack consists of 4 x 18650 cells, which often have protection:

http://www.lygte-info.dk/info/battery%20protection%20UK.html

I wonder if I should remove that protection (if present) but not sure if this wouldn't be too "unsafe" :)

[ddimkin]

It was the thermal protection of the motors - removed it and everything is fine :) The car is ready and drives - maybe not quite as fast as the one of z3_2drive but still quite fine :) Here is the new topic:

http://www.eurobricks.com/forum/index.php?showtopic=99481