Third-party Lego compatible RC Components

[Ximbary]

I have been searching for this for quite some time and couldn't find much information (except for the batterie).

I am searching for a very simple way to use lego motors, but real RC components, like a 11,1 Volt Lipo and also a non-lego receiver/esc.

Has anybody had any sort of experience with that? The official Lego electronics are just so heavy and clumsy that the one and only challenge is to find a decent balance between weight and power. It is so annoying to have a vehicle with 8 XL motors fail (because you can't run fast enough and the sunlight blocks the signal of the very useless IR remote).

I even went through the trouble of purchasing a NXT only to get the link between a 2,4ghz remote and my PF elements. The additional weight was.. disastrous.

I really want to get rid of those receivers. I can do some basic soldering. I have some advanced RC experience but from an entirely different dimension.. I guess my 8S 6500mAh Lipo would blow the lego components through a concrete wall.. :D

Also i have no idea how you would power two independend motors (not servos!) with 1 esc...

I have been thinking about some (lego?) switch, in between a direct connection of a lipo and the lego motor, and the switch being controlled by a standard RC servo, connected to a RC receiver (with a tiny battery). But that sounds kinda clumsy too.. :(

I am using buggy motors, XL motors, servos etc.

These are the Lipos I had in mind:

http://www.maxamps.c...30-111-Pack.htm (see the incredible weight!) 39 grams!

Also I now officially inform all of you, that I have ordered 256 of these: http://www.bricklink...tem.asp?P=45590. I will soon post some pictures of my insane plan for world domination ;)

Edited December 17, 2013 by Ximbary

[bricky300]

everything you need. If you would want to use more escs then you would have to either cut the BEC out of it or use something like this: http://www.conrad.de/ce/de/product/208425/Modelcraft-BEC-Entkoppelungskabel-JR?ref=searchDetail

The esc seen is a Graupner Navy V15R. Of course you can also use other Esc´s. I don´t know if there is a Lipo savety switch build in. Im using two of these one with the cable mentioned and they work fine. You can connect 4 buggy motors to it without any problems

Edited December 18, 2013 by bricky300

[aol000xw]

The key point is how to replace the servo in that picture with the Lego one.

[bricky300]

Well... Z3_2Drive has done it but I don´t exactly know how... theres a topic somewhere in this subforum about it...

Edit: found it http://www.eurobrick...z3_2drive&st=25

The key point is how to replace the servo in that picture with the Lego one.

Why replace it when you can also use the better more acurate and (sometimes) stronger rc servos?

Edited December 18, 2013 by bricky300

[aol000xw]

I like to minimize the use of third party and favor the convenience of easy to use Lego motors. Adapting third party servos to Lego is not always that easy, be it for limited mounting points using customized plates or adapting gears.

My goal is to enclose the RC receptor and power controller in Lego parts, replace the wires/connectors and then be able to use them seamless with Lego PF batteries and motors.

Edited December 18, 2013 by aol000xw

[whale2]

I did some kind of stuff you referring.

I took mini-servo, dropped out it's motor and potentiometer and attached servo controller to Lego micro-motor and bourns 3310C potentiometer. Last one could be fitted into standard technic hole after some treatment by needle file and it's axle is very close to technic axle. Controller then was attached to 2.4GHz receiver and SBEC. Then I did very basic testing of this setup. Whole thing was kind of operational with following issues - first one it has trouble standing still, however I managed to set it still at some position of transmitter joystick. I did not tried any trimming or pot adjustment. And second one - reaction is not very fast.

To solve this issues I'm going to test another pot (original pot in servo has 3.3Kohm resistance, my 3310C-s are 1Kohm and 5Kohm, I only tried 1K) and connect motor via some kind of electronic gate made of 4 transistors. SBEC has ~5V output and Lego motor would definitely work faster if powered by 11.1 V

I expect required electronic components to arrive by the end of this week and if lucky will test it on the weekend. Will post some photo/video.

[Ximbary]

Thanks for all the replies.

I think I am going to try this:

Super light 11,1V Lipo -> Lego electrical switch -> Lego Motor

This setup for every motor.

Now:

Tiny 3,7V Lipo -> RC Receiver/ESC -> Micro servos -> lego switch

1 servo for each switch so that I can forward, idle, reverse each switch.

Good that I only have to modify switch cables instead of motor cables.

Anybody knows if the switches have a thermal protection?

These are the products I have in mind.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=19325 <- 1S lipo battery

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=18822 <- ESC/Receiver combo

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=29547 <- Mega nano servo

All in all only only 21,8 grams(!!!) additionally. Thats all I need to control the switches.

I think I really will try this. Even without an additional lipo I will be able to directly connect a lego battery box to 2 switches without ANY restrictions at all.

Edited December 18, 2013 by Ximbary

[NevynPA]

Now this is the EXPENSIVE way to do it, but it's probably the most accurate...

If you had access to a 3D printer, you could design a new shell for the RC servo that fits lego stud/studless scale and has mounting holes. However, if you don't own or have a friend with a 3D printer, then going down that road is about $1500 USD to start.

[Ximbary]

Yes a 3D printer would be the next step.. but I dont know anybody who has such a thing plus I neither have enough time nor enough spare cash for another machine. I will simply create some lego piece out of the named hardware and some original lego pieces glued together.

I will create something like this:

- 2 switch modules made out of some lego piece, servos and lego switches.

- 1 receiver module made out of some lego piece, receiver/esc combo and the ESC 3,7V lipo.

- 2 lipo modules made out of some lego piece and a very light and small 11,1V lipo, connected to a lego extension wire (to fit the switch modules)

So I can freely arrange the receiver and the 2 switch modules. I should be able to get that for under 100€. I already have a very expensive dual lipo charger with balancing stuff.

Maybe in a few years, when I have more spare cash and when 3D printers are better and cheaper I might try to create this stuff in order to sell it on ebay. With servo perfectly embedded into some 3D printed parts, fully compatible with lego I should get a lot of customers.. theoretically.

Edited December 18, 2013 by Ximbary

[aol000xw]

For 3D printing Shapeways or a similar service can be "cost effective". Btw anyone knows a good 3D printing service in Europe?

What about RC motors, I know that is overkill for Lego gears, but anyways... The problem I found was finding a gear compatible with Lego or attaching a Lego gear to the motor axle.

[Ximbary]

For 3D printing Shapeways or a similar service can be "cost effective". Btw anyone knows a good 3D printing service in Europe?

What about RC motors, I know that is overkill for Lego gears, but anyways... The problem I found was finding a gear compatible with Lego or attaching a Lego gear to the motor axle.

You just have to be cautious when purchasing, programming and using RC motors. Then you wont kill your legos. Of course.. if you connect a motor with 10x more torque then it will rip your legos apart.

But you can easily find a motor with twice the power of a XL motor and half the size/weight.

About the axle attachment to the motor you could try the following: Drill a hole crosswise through the axle of the motor (yes.. risky. Choose a proper drill). Then hollow out a short lego axle by drilling lengthwise. Also drill another hole through the lego axle crosswise. Now slip the hollowed lego axle over the motor axle (with glue) and press a very short metal pin of the perfect size through the crosswise hole (also with glue). That should do the trick. But you definitely need a motor with a thicker axle. all the dimensions are usually listed clearly on the RC shopping sites.

All the less risky ways tend not to be strong enough.

Edited December 18, 2013 by Ximbary

[z3_2drive]

As someone said I have already done this, but I wasn't shooting for light weight, but just something I could use for high power and LONG range. My next video should demonstrate that. My goal was to use as many Lego parts as possible, so I stuck with Lego Servos because they work nice if you implement them properly and they add to the structure of the model itself. I've been busy so I haven't been able to make the topic about my Race Chassis but I'm going to have a two week break starting Saturday so you can expect it to be posted next week. I like your idea of small and lightweight - mine can only be used with large, extremely powerful models, like the off-road tank I'm planning to build next

Here's my RC system: http://www.eurobricks.com/forum/index.php?showtopic=88960&hl=

[Ximbary]

As someone said I have already done this, but I wasn't shooting for light weight, but just something I could use for high power and LONG range. My next video should demonstrate that. My goal was to use as many Lego parts as possible, so I stuck with Lego Servos because they work nice if you implement them properly and they add to the structure of the model itself. I've been busy so I haven't been able to make the topic about my Race Chassis but I'm going to have a two week break starting Saturday so you can expect it to be posted next week. I like your idea of small and lightweight - mine can only be used with large, extremely powerful models, like the off-road tank I'm planning to build next

Here's my RC system: http://www.eurobrick...topic=88960&hl=

;)

If you are looking for powerful creations then you will love what i am going to do with those 256 rubber thingys I have linked in my first post here :P

I will post some pictures when its done.

Also i really love your solution. But I think you misunderstood me a little: I will only use the servos to operate the switches. I wont use them to steer.

[kieran]

Take a look at this

there are loads of other options from the same source

Edited December 20, 2013 by kieran

[BrianZ]

I am currently working on a brick to replace the IR receiver, which will accept 2.4GHz hobby radio controlled signals. Here is how it's going to work. I am going to de-case a HobbyKing 3 channel RC receiver and use that to accept the signals. It is very small when it is de-cased. I am also going to build a circuit board that will translate the hobby servo signals being output from the radio receiver into pulse width modulation signals identical to the output of the Lego infrared receiver. The chip that is going to do that job is a Picaxe 14M2, which costs $4. This is a programmable microcontroller that uses the BASIC computer language, which is the only programming language I know. I am going to use the PULSEIN command on two pins to measure the length of the RC pulses, which normally tells the servos what position to go to. Then, the Picaxe will do a little formula to translate that signal into the pulse width modulation signal. The Picaxe can only output about 10 milliamps though, which is barely enough to light an LED, so I am going to amplify the PWM signals through an H-bridge motor driver chip, the SN754410. This can drive 2 motors, and costs $2.35. However this H bridge chip can only output 1 amp per motor, so that's not going to be enough for the XL motor at stall. I may stack another SN754410 right on top of the other one and get 2 amp output. My circuit board will also have a 5 volt voltage regulator on it for powering the Picaxe and RC receiver. At this point I plan on sticking with the standard Lego battery holders, motors, and servo, so my connections to the battery box and motors will be from cut-up lego extension wires stuck to the top of the brick I encase this in. The final size should be about 1" x 1.5" x 2 bricks tall. I expect to be finished by the end of Janurary, and I plan on documenting the entire project so anybody can easily build it.

I really wish Futaba or somebody would build servo cases, RC receivers, battery holders, and motor housings with Lego connections. I feel like there is a lot of potential here, but the Power Functions infrared system just sucks for controlling cars.

Brian Z

[cybermaster7]

Here is my modification done 2 years ago. Vex robotic rc control integrated with lego motors. Can control up to 6 motors at once.

[Boxerlego]

The main question that is behind this third-party stuff is, How is it compatible with Lego? When it come to electrical circuits everything is compatible. I bought a bunch of electrical components to build a custom RC circuit... It cost me around 20$. I spare all the details and tell everyone this. You can either buy the cheap RC car and use that electrical system to power your model and mod of that. Or you can go buy the expensive RC car stuff and have fun with that. I have great success in using the 8879 speed control to control the power to the 18 Volt motor with the motor control circuit you can see below. Also the controller of choice for me is the 8879 speed controller and that is what I am going to keep on using. The picture of the 8879 controller shows it with the antenna on the table below, this is a Idea that I have been contemplating. The video I made here shows what I was able to do with the 18 volt motor and motor control circuit plus all that was able to hook up and work with the V1 IR receiver.

Size is the most important factor and that underlying fact is you are building with Lego which can take any size shape as you want to construct it to.

[Boxerlego]

Here is something for you to think about. All I need Is this transmitter and proper antenna and I am done with this side of the mod.

[Boxerlego]

Sorry for the Triple Bump But I finally got all the bugs Out and manage to make my own Lego Compatible RC circuit. Here is a test Go.

Edited December 23, 2013 by Boxerlego

[MrNumbskull13]

That's pretty cool! :) I have the speed remote too and I was wondering if I gave it an antenna would it work better (bigger range) with the stock pf receiver?

[whale2]

I managed to get it work.

2.4Ghz RC system, controller from some de-cased micro-servo, Bourns 3310C potentiometer and Lego micro-motor driven via L293D.

[aol000xw]

Is that a Lego plane wing?

[Boxerlego]

That's pretty cool! :) I have the speed remote too and I was wondering if I gave it an antenna would it work better (bigger range) with the stock pf receiver?

Thanks! There is a bunch of stuff I want to talk about on this. Yes the PF speed remote would work better with the antenna to transmit to the PF receiver. It uses a RF transmitter and receiver making the wireless communication link between the two devices. The controller is simple to make. All you need is an antenna and the transmitter. Also I got some extra parts to run the all 4 channels down one antenna. I might start my own topic on this because it is a topic in it self besides the OP wants to completely remove the receiver and Truly put in place a Third-Party RC Unit. Which is still pretty cool.

[whale2]

Is that a Lego plane wing?

Well, yes :)

[aol000xw]

Then that is a BIg plane.