Draft

The Various Systems

Over the years there have been a number of Lego motor solutions.

4.5v

Early kit, uses two pin connectors and round bodied motors and battery boxes.

12v

Fairly rare train power system. Uses 4th rail style metal conductor rail between the running rails. Apparently not sold in the US.

9v

Common from the late 80s right through the 90s. Uses a 2×2 plate with conductors built into the knobbles and recesses. Can be placed at 90° and still works. Some sensors, lights, sounders and switches available as well as motors. Common battery boxes are cuboid with buttons, either containing a single 9v battery or 6x AA.

Power Functions (PF)

No longer sold by Lego, but there are a lot of aftermarket solutions available.

This solution uses weird 4 pin connectors. Nominally 9v power. The connectors are stackable, but no longer can be used at any 90° rotation. The additional pins provide continuous power. The connectors are no longer reversible, but reversing switches are sold. It is possible to buy new aftermarket connectors cheaply to make custom cables and adapters.

Infrared, radio and Bluetooth controllers are available with up to at least 4 motor channels. This includes variable speed and servo control, although the latter is rare.

Powered Up (PU)

The current official solution, which uses crimped 6 pin connectors. The additional pins carry data and motor IDs. The connectors are no longer stackable, effectively limiting you to one motor per port on a controller even if you want to run two in unison. Voltages have changed compared to previous systems. Power is 3.3v, motor voltage seems to vary depending on your power source.

What Should I Use?

Which Family?

If you’re planning to buy for your own builds, I recommend going with Power Functions. Both original and third party products are still readily available, and the connectors are way more flexible than the newer Powered Up stuff. On top of this, the availability of connectors lets you make your own cables easily and even connect custom parts. Lastly, very cheap third party components are sold online enabling you to build complex models using many motors and switches and controllers, without needing to remortgage the house.

What Controllers?

Which controllers you buy depends on what functionality you want, and how much you’re willing to spend. Here I’ll discuss 3rd party options by price range rather than OEM equipment, and specifically Power Functions. Here I just consider the power and control and not motors or other peripheral parts.

Sub £5

The most basic solution is just a switched power bank, such as the following.

This lets you drive a single motor in forward or reverse, or multiple motors in unison if you stack connectors on the output. The box takes 6x AA batteries. Cost is approximately £2 excluding shipping.

Sub £10

To add remote control to the above, after market transmitters and receivers are available.

Combined, these cost approximately £5.50 and despite appearances, these aftermarket versions are actually radio based, unlike the Lego originals which are InfraRed. Using radio signals means they do not need line-of-sight. They have four channels so you can use four sets at the same time without interference, or by switching the selector, using one transmitter with four recievers. The two main controls are digital switches, one for each of two outputs and they each support forwards and backwards. Imagine tank tracks, but only full speed forward, backwards and off, for each track. The small black switches allow you to select the default direction of travel so you don’t need to worry about getting motors to rotate the correct way. You can stack multiple motors on a each of the two outputs to drive more motors in unison.

You still need the previous battery box, so the combined total is approximately £7.50, but you could run multiple recievers from one power source.

For a similar price, there is a variable speed controller that works with the same reciever, it is designed for trains and has two channels with seven speed settings. I don’t recommend it as my third party one is not very good. It misreads input and sometimes steps the speed in the wrong direction, and feels a bit too cheap. It also only really makes sense for trains and static models and not cars and other vehicles where you want to steer.

Sub £20

For this you get four channels and a nicer remote control. The battery box is rechargeable lithium and comes with a battery, the controller needs some AAA batteries. The kit I found while checking prices comes with two “medium” motors. As well as the provided remote control which only provides forward/off/reverse (no speed control) for the four output channels, this box can also work with a mobile phone app which gives variable speed and flow chart (like Scratch) programming!

At a total price of approximately £13, I believe this is a staggeringly good deal!

Sub £30

In this category, we look at the Mould King (a respected third party brand) 6ch set. The controller that comes with this set supports variable speeds on four channels and forwards/off/backwards on two more. As above, it also supports a phone app and flowchart programming.

At approximately £28, this is another amazing deal, although perhaps not as good value as the previous option, but only because that included two motors. This option does offer a lot of functionality and personally, having an analogue physical controller would be worth it to me because I’m not a fan of using the mobile app to get the variable motor speed functionality.

Motors

For a huge amount of information about the electrical properties of various official Lego motor types, see the motors section of the philohome.com website.

Third party motors for Power Functions mostly follow the same pattern as OEM parts. There are commonly a Medium, Large and Extra Large motor. As well as various more specialised solutions such as small motors built into bricks, servos, train powered bogies and motors built into buggy swing arms. The following is a selection of the sort of thing available.

Generally motors with clear parts and red bodies are higher speed or torque versions. Most of these third party motors use a bit more current than the Lego originals.

Prices are between about £2.50 and £5 for most of the normal style motors.

Be aware that third party servos only tend to do centre, forward 90°, backwards 90°, even when used with an analogue controller. Sometimes this contradicts listings (on Amazon) where uninformed UK sellers have just copied and pasted Lego’s own description.

I think the small motors are cute, although I don’t have any.

Recently Mould King have been making some special high precision motors for their Pen Plotter kit (~£125). These motors are something Lego doesn’t offer and allow small precise movements in one mode, while still allowing for large sweeping movements in another.