Power Functions (PF) help - Need a detailed break-down

[emilyan]

Hello!

INTRO: I am new on this forum but not new to legos. It's been almost two decades since I played with legos (as a kid) and recently decided to invest in several sets (42009, 8110, and 9398) to get some parts to work with. My next step is getting all the power functions I may ever need to build something cool.

Let me define "cool" because my goal is make this a hobby where I make my own creations (I think MOC is the name?). I love the idea of remote controlled functions and planning to buy a whole lot of PF parts from lego directly. However, I am still struggling to understand what I will need... Hoping someone with knowledge on the subject of PF can break the parts down for me.

How do the PF components interact?

Power unit / Motors:

• How many motors / components can you hook-up and draw power from one power unit?
  
• The power unit is 9V - so if its possible to hook-up 2 motors, each motor will be operating at 1/2 the normal power & speed vs when you hook up just 1 motor?
  
• How long does the power unit last say if you hook up 1 large motor and let it run until it dies?
  
• Any other limitations / things I need to know about the power unit?
  

Cables / Switches:

• I noticed there are extension cables and switches you can buy - these are only for convenience purposes?
  
• My understanding is the switch allows you to control the power source from another location.
  

IR Remote / Receiver:

• This is the newest part of legos to me (aside from mindstorms) - how do these work exactly?
  
• The IR receiver has 4 channels - does this mean you can have a maximum of 4 IR receivers (and thus control a maximum of 4 motors)?
  
• One IR remote can switch between all 4 channels - is there any reason to get multiple remotes?
  
• Is there ANY reason to get more than 4 IR receivers for the purpose of building ONE custom model?... so having a 5th IR receiver on one model is basically useless?.. please correct me if I'm wrong!
  

• As far as remotes, I notice there are 2 types:
  
  1. IR Remote Control
     
  2. IR Speed Remote Contros
     
     • What is the difference between these two remotes??
       
     • Are both necessary for someone interested in building various controllable functions into a model?
       
     • Are both remotes V2 and work with the IR receiver (which is also V2)?
       
     • My understanding of the two remotes is this:
       
     1. 
        
     2. The basic IR Remote controls power source On/Off and rotation direction.
        
     3. The speed IR Remote controls power source On/Off, rotation direction as well as rotation speed (slow,med,fast)
        

     As far as getting these PFs, my plan is this (please let me know if I am missing something or getting too many receivers/remotes):

  • buy 4 IR receivers
    
  • buy 2 basic remotes and 1 speed remote
    
  • buy 2-3 switches and extra cables
    
  • buy any additional motors I may ever need
    

  Sorry this post is so long! I am hoping I can close all the gaps in my understanding of PF components in one thread.

  Thanks so much,

  -Emilyan

Edited September 17, 2014 by emilyan

[Zerobricks]

You can find more info on Lego offical site:

http://powerfunctions.lego.com/en-us/faq/default.aspx

Here are my experiences:

How do the PF components interact?

Power unit / Motors:

• How many motors / components can you hook-up and draw power from one power unit?
  
• As is states on FAQ: As a rule of thumb, you can drive 2 Power Functions XL-Motors, 3 Power Functions Train Motors or 4 Power Functions M-Motors at the same time from one Power Functions Battery Box. The XL-Motor requires about twice as much power as the M-Motor.
  
• The power unit is 9V - so if its possible to hook-up 2 motors, each motor will be operating at 1/2 the normal power & speed vs when you hook up just 1 motor?
  
• You can do that by either hooking the motors to receivers and setting power level with the train controller (IR speed controller) or hooking up the motor to the LiPo battery box which has adjustable speed dial.
  
• How long does the power unit last say if you hook up 1 large motor and let it run until it dies?
  
• Dont know depends on the load of the motor, batteries, etc... Probably hours
  
• Any other limitations / things I need to know about the power unit?
  
• The power unit has cca 800mA current protection, so thats all the power you can get from it
  

Cables / Switches:

• I noticed there are extension cables and switches you can buy - these are only for convenience purposes?
  
• These also allow you to connect older model, most notably RC motors
  
• My understanding is the switch allows you to control the power source from another location.
  
• Its like an extension and also simple ONE DIRECTION - OFF- OTHER DIRECTION control
  

IR Remote / Receiver:

• This is the newest part of legos to me (aside from mindstorms) - how do these work exactly?
  
• Its an IR receiver which allows you to power the two motor channels independently (blue and red)
  
• The IR receiver has 4 channels - does this mean you can have a maximum of 4 IR receivers (and thus control a maximum of 4 motors)?
  
• NO, this allows you to control 4 receivers independently one on each own IR channel - therbye indcontrolling 8 motors
  
• One IR remote can switch between all 4 channels - is there any reason to get multiple remotes?
  
• YES, so you can controll all motors at once
  
• Is there ANY reason to get more than 4 IR receivers for the purpose of building ONE custom model?... so having a 5th IR receiver on one model is basically useless?.. please correct me if I'm wrong!
  
• Only if you need more power for that function (the Receiver and battery box have current limiters)
  

• As far as remotes, I notice there are 2 types:
  
  1. IR Remote Control
     
  2. IR Speed Remote Contros
     
     • What is the difference between these two remotes??
       
     • Are both necessary for someone interested in building various controllable functions into a model?
       
     • The remote control allows you to control model in real life but with only full power. The speed remote allows you to control the power to the motor in 7 levels and once you set the power the reiver remembers it and the motors keep running at that power untill you send it another instruction for power or speed change. For driving vehicles the IR remote is more usefull, while for trains and continuing running stuff the Spped remote is more suitable
       
     • Are both remotes V2 and work with the IR receiver (which is also V2)?
       
     • Yes the work on both receivers
       
     • My understanding of the two remotes is this:
       
     1. 
        
     2. The basic IR Remote controls power source On/Off and rotation direction.
        
     3. The speed IR Remote controls power source On/Off, rotation direction as well as rotation speed (slow,med,fast)
        

     Hope this helps you a bit...

[Blakbird]

That's a lot of questions. I'll try to give some brief answers, but keep in mind that the entire PF protocol is open and available to read if you want to know how it works. There have also been a lot of tests of the motors done by Philo.

How many motors / components can you hook-up and draw power from one power unit?

By "power unit" do you mean battery box? The standard 9V battery box is limited to about ~1 Amp, so at 9V the maximum power is 9W. There's no theoretical limit to the number of components you could hook up to a battery box as long as they are drawing a combined current of less than an Amp. I've had 9 motors, 4 receivers, and a bunch of LEDs all connected to one battery box.

The power unit is 9V - so if its possible to hook-up 2 motors, each motor will be operating at 1/2 the normal power & speed vs when you hook up just 1 motor?

No, not really. The voltage stays the same (roughly) no matter how many motors you hook up. The power doesn't change any as long as you stay under the current cutoff, and once you do they would all cut out at once. The speed of a motor has nothing to do with how many are hooked up as long as they are hooked up in parallel (which is the only way to do it unless you cut wires).

How long does the power unit last say if you hook up 1 large motor and let it run until it dies?

There is no way to answer that. The time it takes will depend on the capacity of you batteries and the amount of load being driven by the motor. If there is no load on the motor, it would probably run all day. If it was working at maximum and drawing an Amp, it might last less than an hour if you are using cheap batteries.

I noticed there are extension cables and switches you can buy - these are only for convenience purposes?

Mostly the extensions are for getting power to motors which are far away, but they can also be used as converters to use an old 9V power system or old 9V motors.

My understanding is the switch allows you to control the power source from another location.

Essentially, yes. A switch allows you to turn a load (motor or lights) on and off independent of the battery box switch. It allows you to reverse direction of a motor. It has no effect on receivers because they get their power from an unswitched wire.

This is the newest part of legos to me (aside from mindstorms) - how do these work exactly?

I have no idea how to answer this. "How do they work exactly" could start with a description of basic physics and chemistry. If you really want to know, reading the PF specification is the way to go. If you are looking for a more cursory answer, they are infrared receivers which use pulse width modulation to control the speed of 2 outputs.

The IR receiver has 4 channels - does this mean you can have a maximum of 4 IR receivers (and thus control a maximum of 4 motors)?

Not quite. Each IR receiver has 2 outputs, so it can control two things on a given channel, but you can also have more than one motor on a given output (stackable). This means there are a total of 8 independent functions that can be controlled remotely if you have 4 receivers.

One IR remote can switch between all 4 channels - is there any reason to get multiple remotes?

Yes. Multiple remotes allows you to control functions concurrently. If you are willing to control them all one at a time, then you can get by with one remote.

Is there ANY reason to get more than 4 IR receivers for the purpose of building ONE custom model?... so having a 5th IR receiver on one model is basically useless?.. please correct me if I'm wrong!

The 5th is essentially useless, although a few enterprising builders have used a 5th receiver with an additional battery box to get around the current limit and get more power. For example, you could have two motors driving your vehicle, each on a different receiver on a different battery box, but on the same channel.

What is the difference between these two remotes??

The "regular" remote is usually what you want. The other remote was really made for trains. The standard remote has no gradations. Each function is either on-forward, on-backward, or off. Nothing in between. You have to hold down the lever and stay within range of the model to keep the signal going. The train remote has forward and backward each in 7 steps so you can control speed. It also does NOT need to stay in range of the vehicle. If you tell it to go full speed ahead, it will keep doing that until you tell it to stop. It is very difficult to control vehicles with this remote because it does not return to center or to off. The ideal R/C remote would be a cross of these two, but does not exist.

Are both necessary for someone interested in building various controllable functions into a model?

I wouldn't say they are both necessary, but it is useful to have one of each for testing the best way to control each type of function. A very large model might use one for some functions and the other for other functions to work best.

Looks like you have a good plan for getting a selection of PF components to start. Make sure you get at least a couple of each size of motor. The E-motor is really not very useful for powering anything (it is made to be a generator), so you might skip that one.

[aol000xw]

Power unit / Motors:

• How many motors / components can you hook-up and draw power from one power unit?
  

Depends on the power unit be it AA, AAA or Rechargeable Li Ion. Everything has thermal protection so no danger. Operating at the same time a couple XL and a servo

• The power unit is 9V - so if its possible to hook-up 2 motors, each motor will be operating at 1/2 the normal power & speed vs when you hook up just 1 motor?
  

Hooking more motors increases current draw, there is some voltage drop but mostly work the same

• How long does the power unit last say if you hook up 1 large motor and let it run until it dies?
  

I don't think there is a definitive answer, Using alkalines? NiMH? Eneloops? rated at how many mAH? At no load 10 hours on average?

• Any other limitations / things I need to know about the power unit?
  

Draw too much current from it and thermal protection kicks in and shuts down.

To keep two motors rotating in different directions a switch is needed.

AA battery box with rechargeables weights a ton

The LiIon unit is very expensive.

Cables / Switches:

• I noticed there are extension cables and switches you can buy - these are only for convenience purposes?
  

​As far as i know yes.

• My understanding is the switch allows you to control the power source from another location.
  

​And as stated before is necessary to independently reverse direction or start/stop motors attached to the same source

in older designs reversing the plug did the trick, changing polarity, not anymore.

IR Remote / Receiver:

• This is the newest part of legos to me (aside from mindstorms) - how do these work exactly?
  

​Poorly... Is Infrared, two channels per Remote, 4 remotes max. connect As many as 4 of them to one or more battery boxes and hook the motors lights to the receivers....

• The IR receiver has 4 channels - does this mean you can have a maximum of 4 IR receivers (and thus control a maximum of 4 motors)
  

4 receivers, but each receiver has 2 channels and each channel can take several devices (motor or lights) The drawn current is the limiting factor.

• One IR remote can switch between all 4 channels - is there any reason to get multiple remotes?
  

4 Remotes to use everything at once,

• Is there ANY reason to get more than 4 IR receivers for the purpose of building ONE custom model?... so having a 5th IR receiver on one model is basically useless?.. please correct me if I'm wrong!
  

covenience , you may design specific remote configurations for specific models. and if you keep the model buitl probably the remote too.

• As far as remotes, I notice there are 2 types:
  
  1. IR Remote Control
     
  2. IR Speed Remote Contros
     
     • What is the difference between these two remotes??
       

​The second one is better in theory than in practice. It is somewhat proportional. "Useful" for speed control and servo progressive motion.

• Are both necessary for someone interested in building various controllable functions into a model?
  

No​

• Are both remotes V2 and work with the IR receiver (which is also V2)?
  

Remotes aren't V​2, receivers are, but everything can work together, Only difference is V2 receiver can handle some more current.

• My understanding of the two remotes is this:
  
  1. The basic IR Remote controls power source On/Off and rotation direction.
     
  2. The speed IR Remote controls power source On/Off, rotation direction as well as rotation speed (slow,med,fast)
     

Mostly yes, The speed remote uses a dial, does not automatically return to cero. It has a reset button.

If I did not get anything wrong myself I think that is pretty much it.

[Captainowie]

Some good answers here - I've got nothing really to add to those.

However, if you're concerned about the limitation of the remote control system, you might want to check out the SBrick (http://www.eurobricks.com/forum/index.php?showtopic=97800), a 3rd party product which uses bluetooth instead of IR. This was a kickstarter campaign that was recently funded, so assuming they get their production run going, you should be able to purchase one in the next few months.

Owen.

[emilyan]

Guys, must say these were excellent responses - I saved everyone's feedback in a word doc and printed it out so I can absorb it better. I really could not have expected better feedback than this. I'll check and see if I have any other questions in regards to the PFs and get back to this thread. For now, thanks much to Zblj, Blakbird, and aol000xw!

As far as SBrick - quite fascinating! I am going to keep my eye on this development and leard the more basic PFs first. However I do hope the SBrick pulls through and I can see myself buying this sometime next year (assuming it takes off and works as advertised).

Edit: My remaining debate is whether I should own 2 std. remotes + 1 speed remote vs 3 std. remotes + 1 speed remote.

I am pretty set on just going ahead and buying additional 4 IR receivers so I have maximum control over my set.

Edited September 18, 2014 by emilyan

[Blakbird]

Edit: My remaining debate is whether I should own 2 std. remotes + 1 speed remote vs 3 std. remotes + 1 speed remote.

3 std remotes plus a speed remote is a good option because then you can make a controller that works with everything at once without changing channels.

[aol000xw]

I find the speed remote so wildly flawed

[dr_spock]

Edit: My remaining debate is whether I should own 2 std. remotes + 1 speed remote vs 3 std. remotes + 1 speed remote.

I am pretty set on just going ahead and buying additional 4 IR receivers so I have maximum control over my set.

It depends on what you are controlling and how. I have one speed remote to control several trains. It is not hard changing the remote's channels on the fly. I find it more useful to have more receivers and motors and battery boxes for multiple models.

[Splat]

If you have the funds available, you might want to buy the new Wheel Loader (42030)

It costs US$249.99, but it has the following Power Function (PF) components:

• 1x Standard AA Battery Box
  
• 1x L Motor
  
• 1x M Motor
  
• 1x XL Motor
  
• 1x Servo Motor
  
• 2x IR Remotes
  
• 2x IR Receivers
  

The PF components alone add up to US$119.10 from Lego directly, but this set also has a range of parts that will help get you going - especially if you like yellow.

You can see the full parts list on BrickLink.

[Lucio Switch]

I have a couple of question to add:

There is different in power erogation between the standard AA Battery box with no rechargeable battery (9V) and the rechargeable LiPo box (7.2V)?

If I buy a rechargeable LiPo box it will become with a transformer for charging or I must buy it separately?

[Blakbird]

There is different in power erogation between the standard AA Battery box with no rechargeable battery (9V) and the rechargeable LiPo box (7.2V)?

Philo analyzes the battery boxes on his page. The short answer is that the difference between the 9V standard box and the 7.2 Li-Po box is mostly an illusion because the voltage of AA batteries drops off so quickly. In practice you get about the same power out of each.

If I buy a rechargeable LiPo box it will become with a transformer for charging or I must buy it separately?

You must buy it separately.

[captainmib]

So, i just assembled the 42030.

I have setup all things properly, but the receiver controlling forward/backward motion and the tilting of the bucket is responding really bad.

The range is max 30 cm.

I can control the steering from 2 meters away easily. This is done with the other receiver.

Do i have a bad IR receiver, or is there anything else that might be broken?

Edit: can we turn this into a general power functions help and questions topic? Might be usefull (pinned etc.)

Edited November 6, 2014 by captainmib

[Zerobricks]

So, i just assembled the 42030.

I have setup all things properly, but the receiver controlling forward/backward motion and the tilting of the bucket is responding really bad.

The range is max 30 cm.

I can control the steering from 2 meters away easily. This is done with the other receiver.

Do i have a bad IR receiver, or is there anything else that might be broken?

Edit: can we turn this into a general power functions help and questions topic? Might be usefull (pinned etc.)

Whats also connected to the second receiver? Steering or drive? How does that work?

EDIT Yes I guess you have a bad receiver... Maybe try swapping receivers?

Edited November 6, 2014 by Zblj

[AndyCW]

Swap receivers and see if the issue follows the suspect receiver. If so you can narrow down the failure to a receiver, if not then you need to troubleshoot further.

v/r

Andy

[captainmib]

So, i swapped the remote control functions, the receivers, etc. and it's definitely the receiver.

The first receiver works even from 4 meters away, the other barely at 30 cm.

I'm a bit disappointed. My first remote controlled technic set, and then this happens.

I guess getting in contact with customer service is the next step.

[MajklSpajkl]

I suggest you do contact the costumer service, they'll solve your problem, at least in my experience getting a new servo was no issue...

[AndyCW]

Before you contact customer service, ensure that the remote isn't the issue and that the problem is repeatable.

v/r

Andy

[captainmib]

yeah, i switched the remotes aswell, they work fine.

Both remotes had trouble with the same receiver, but worked fine with the other.

[phoenixr]

Just to clarify a few things about the speed remote: The dials work much like a computer mouse's scroll wheel - there is no center, and if you rotate too much at a time, it will skip - it will only step one even if you rotated 3 steps. So you can't really use it for steering/accelerating a car, because the response is pretty slow and unreliable. They are intended for trains.

The regular IR remote can only control full forward / stop / full back. This works pretty well for a car for drive and steering, but it's pretty limited, not like the more sophisticated analog RC cars you would find, it's more like the cheap ones. The problem I ran into is that I couldn't make a fast car, because the high gearing resulted in too much torque at start (from zero to full speed) and the gears would slip - they could very well break if pushed. The SBrick (see below) should allow for gradual acceleration.

The servo is very good for steering, it turns 90 left, center or 90 right. So you don't have to have a return-to-center mechanism for your steering. With the speed remote you could control it step-by step, 7 steps to in each direction (the speed remote problems do apply).

Also, the IR system does not work well outside, it will not be reliable over a few meters due to sunlight. Also there is a problem of line-of-sight. Indoors it works, because the walls reflect enough so you don't have to point the remote directly at the sensor, but it's still not perfect - you can't drive under a table or put something on your MOC that covers the sensor.

And as someone mentioned, the SBrick. I was in the first 500 for it, and expecting to get it within the month. It should allow us to control the motors in an analog way (1000 something steps), without lag or the sequential nature of the speed remote. Also, one SBrick control 4 functions, compared to the 2 of a PF receiver. And the remote is any modern iOS/Android tablet or phone.

I don't have first hand experience with it yet, but the videos that the beta testers put up are very impressive. I have previously set up my phone with a PS3 Sixaxis bluetooth gamepad for games and such, I hope to use the joysticks and buttons on that to control my MOC.

I recommend you not invest in the IR system and go for one or more SBricks - you can find videos on their site and youtube of it in action.

[MajorAlvega]

Hello. I'm one of the SBrick beta players testers.

The SBrick is very good but not that good: you only get 256 steps, not "1000 something steps" :) (and the low range 0..30~40 is somewhat unusable with the motors i've tested)

Now what picked my attention in SBrick is that the remote can be in fact ANY modern system with Bluetooth 4.0 in it... I'm current using my Ubuntu laptop but already showed that it's possible to use a Mindstorms EV3 (with a custom OS, ev3dev = Debian for EV3) and between both there is also the mighty Raspberry Pi... and I'm prety sure there will be someone using Arduino, it's just a matter of time.

I'm already using a wireless gamepad and a wiimote. If/when SBrick picks up, there will be people using voice recognition, computer vision, bluetooth triangulation... With the new Microsoft Kinect 2 expect great amounts of awsomness!

[Gnac]

HAH, I wish I'd looked at this thread before buying a Speed Remote to control a vehicle chassis. As mentioned above, the response time is much too slow for quick actions (such as steering in the opposite direction, especially with a servo motor*), but... it's got me thinking.

Could I have a regular IR remote AND a Speed Remote on the same channel without interference - for example, using the regular IR remote to control steering, and the speed remote to keep the vehicle at a slow crawl when needed?

can we turn this into a general power functions help and questions topic? Might be usefull (pinned etc.)

I fully support this suggestion!

* EDIT: Also, using the Speed Controller with a Servo Motor sort of defeats the nifty auto-centre thing it does, but oh well. I learn the hard way.

Edited December 28, 2014 by Gnac

[pcfw]

Can I pop a small question here? Answer is probably no, but are Wedo sensors, lights Power Function devices?

[zux]

Could I have a regular IR remote AND a Speed Remote on the same channel without interference - for example, using the regular IR remote to control steering, and the speed remote to keep the vehicle at a slow crawl when needed?

Well I cannot test it here now, but I see no reasons why it shouldn't work. From our LUG meetings I found that the last command sent from either controller will be prioritized.

I just wonder what would be the result in case your moc is, let's say, crawling, then you push on another controller to go full speed and then release the control. Would it return to crawling speed or stop?

Can I pop a small question here? Answer is probably no, but are Wedo sensors, lights Power Function devices?

Lights are definitely PF. According this page sensors and hub do not have PF in their naming, Edited December 28, 2014 by zux

[pcfw]

Or maybe yes because Wedo sensors can be labeled by shift-click on it?

I my asking in this thread considered hijacking thread, if yes, sorry and will not do again. If no, hope to get an answer