Sunday, May 24, 2015

Tips and Curiosities: Power Functions

The LEGO Power Functions system has more possibilities and hidden functions than you probably think.

I will show you a few examples. Some of them are well known, but others don't.

You can use a 9V train controller to connect any Power Functions element.

To do it you only need to add an empty battery box between the controller and the IR receiver

All Power functions have a written code with numbers and letters.

The code tell you when the element was made.

In this IR receiver 02K8: that means 2nd week of 2008.

07K4: 7th week of 2014

20K3: 20th week of 2013

The PF system has a double wire connection:

- One always on for IR receivers and servos.
- Second one to control motors and lights.

With the PF lithium battery you can control the speed of the second one, keeping the other one always on.

Using this double function you can do two things at the same time using the same battery.

I used this function for my Porsche 911 4 years ago ;)

This looks complex, but it has an important benefit: IR receivers are very delicate under heavy stress, and with this mechanism you protect them.

The PF Switch (pole reverser) has many possibilities.

You can use it like a extension wire or as a motor controller.

And using the same double wire system as the previous tip, you can control a motor using the same wire.

All LEGO 9v and PF motors are actually a 12v motors.

LEGO use them to avoid you break them under heavy stress.

So you can use it as hard as you want, it is almost impossible you break any of them. I have never broken a LEGO motor and I use them very hardly.

The PF Train Remote controller is usefull to control the speed of a motor.

But there are two ways to stop a motor started by train controller. You can use the red botton of the train controller, or you can use a starndar PF IR controller.

You can connect tons of motors to the same battery box.

But only if they are not under load. If you load one of them the battery power protection will cut the energy.

A Lithium battery can handle up to more or less 12XL motors, a AA battery box some more...

You can connect a IR receiver to a IR receiver, and both will work perfectly.

Using again the double wire system. You still will have 4 free PF outputs.

I used this in my Beetle

If you connect a PF motor and a PF servo to the same IR receiver output, both start at the same time. But the servo will not stops until the motor are stopped.

This happens because even if the motor is turned off,  if it is still runnig it works as a generator creating a signal that keep the servo working.

Some M motors don't work properly with some V1 receivers

I have at least 3 M motors from different years with the same problem in combination with receivers V1. Theses motors have the same problem since they were new.

If I connect these motors directly to a V1 receiver they don't work, but they do it if I place a extension wire between them!!

That is very strange, the problem is related with the electric contacts.

Of course if I connect the motors to the V2 receiver they works fine.

A video showing all these tips:


  1. Muchas gracias tocayo por toda esa información.

    Saludos Fernando

  2. Hi thanks a lot for the info I'm 15 and I'm just getting used to adding the battery system and the wires for my models. WHERE do you get the batteries from????

  3. In Lego shop or in bricklink.com

  4. Hey Sheepo. I hope you are doing well. I want to make a car with 7 speed gearbox but it's so light so it can move smoothly with L motor. I want to add m motor for steering. Is it better to use ir receiver V1 or V2 for one m and one l motor?

  5. You can use any receiver you want, both will work fine.

  6. Thank you very much for your help.

  7. hola, primero que todo felicitaciones por tus modelos, son extraordinarios.
    una consulta respecto a los motores, tengo un servo comprado hace solo unos meses que funcionaba impecable. hace poco estuve armando un auto y el motor se queda pegado al llegar al tope (90 grados) sin devolverse.

    es necesario girar en el otro sentido para que pueda volver a su posicion inicial (centro)

    esto solo ocurre al girar a uno de los lados, al otro, aun llegando a 90 grados y manteniendolo ahi, al soltar el control se devuelve automaticamente.

    tendra algun problema irreparable? te ha pasado?

    atento a tus comentarios

  8. otra pregunta, el motor servo lo compre para la dirección de mis super cars, pero me he dado cuenta que para este caso tu solo usas M motors, es por que los servos son muy delicados para grandes construcciones? o porque son mas débiles que los MMotors? o solo es tu estilo de contruccion?

    atento a tus comentarios y felicitaciones de nuevo

  9. Hola, ese servo esta estropeado, en ese caso contacta con el servicio de atencion al cliente de LEGO es muy muy bueno y seguro que te ayudan.

    Yo no uso servos en mis coches grandes porque no tienen suficiente potencia para girar la direccion, a parte usando un mando PF normal no tienes precision en el giro, cosa que con un motor M si.

  10. Hey sheepo. Which one is a better motor for drive? m or l or xl motor? And which one is the fastest

  11. None is better for drive, just different. The most powerfull is the XL engine, and L the fastest.

  12. So which motor is better for drive? the rc buggy motor?

  13. And what is the e motor?

  14. RC buggy motor is de most powerfull motor ever made by LEGO, but it has problems when you use it with PF IR recevier. e-motor is a motor designed to be used as a generator.

  15. IF I use an Xl motor for drive and m motor for steering, will the PF IR receiver v1 work fine?

  16. Thanks a lot for answering all of my comments Sheepo.

  17. Hi there. I have a motor with an written code "35N5". What year was the engine made? The motor don't have the "K" word. Thanks and excelent job!

  18. That motor is from week 35 of year 2015. Honestly I don't know what means the letter of some PF.

  19. is it also possible to power servo with 12V?

  20. I don't know... but I don't think so

  21. Hello, is it possible to program an M motor as a servo?

  22. You can add an autocenter mechanism to a M motor, but you can not get the step-by-step function of the servo motor

  23. cool how do you get the rc mottors?