We've been having a whole lot of fun on this project!
A friend kindly donated the Hogwarts Express set 75955 for us to play with.
These little gadgets are basically Bluetooth remote management systems for the LEGO Power Functions components.
Bizarrely the Hogwarts Express doesn't come with any track, so here's what we put together...
- The Hogwarts Express set 75955
- An SBrick Plus
- A Power Functions Train Motor
- A Power Functions Battery
- A bunch of LEGO train track
- A load of Light My Bricks lights
Here's our set all built and ready to go!
Fairly simple - we want the train to move and we want some light!
More specifically we also want to see our Light My Bricks lights running off the same integrated Power Functions battery and control system.
Before we even get started on the lights the challenge is clear - fitting a decent power supply in there!
We have an 88000 PF battery pack which takes 6 x AAA batteries and has basic on/off and forward/reverse controls on top. It's small by LEGO PF standards at 8 studs x 4 studs x 4 bricks high. (And that's not counting the overhead needed to actually plug anything into it)
The only logical place to put that battery is the coal car (Tender) between the engine and the passenger carriage. So we'll need to make that bigger.
To remote control this train I want to use our new SBrick Plus - so we need to accommodate that. That little gadget is 4 studs x 4 studs x 2.5 bricks high.
And to use the SBrick as the brains of the outfit we need to have all the power connected to it one way or another which increases our cabling requirements.
Wiring the Train Motor
This part wasn't too much of a challenge using the 88002 train motor. Ours is an old and battered one and the top swivel post was broken. Which is handy since we weren't going to use it anyway and it fits more easily now!
We removed the undercarriage from the engine easily enough and built up the motor with spare pieces to give a studded top suitable to securely fasten to the underside of the train
The two motorised axles on the motor are too close together to allow us to use three sets of wheels like the original Hogwarts Express train engine. A shame but we couldn't find any option there. Fitting the connecting rod to make the piston effect work between the wheels was no problem however.
Wiring the Lights
Having had a look at the options we have a clear objective for lighting this train:
- 2 Headlights at the front
- Light for the driver's cabin
- Flames in the furnace opening
- Passenger cabin lighting
Starting at the front we removed the engine block and fitted front headlights in the usual way.
The wires were neatly hidden under the engine block and behind the furnace is a handy compartment where we could hide a 6 port expansion board. This was used to connect up the driver's cabin and a light for the furnace itself.
We didn't put a flicker effects board in but that compartment is big enough so that would be easy to add and would make a great fire effect in the furnace opening.
A single long cable was connected from the expansion board and out the back of the train to connect to the power in the coal tender.
Wiring up the passenger carriage was simple enough with a single white strip light doing the job nicely. As usual we stuck the strip light to a 1x6 plate to make it easy to attach to the ceiling. Using two lights at either end of the carriage would have been good but one is just enough for this demonstration. We also made good use of a 1x1 inverted tile to hold some of the excess cable out of the way on the ceiling - a great trick to keep it looking neat!
Finally we used a PF Connector cable and a 6 port expansion board in the coal tender - this connected our front and back lights to the SBrick.
Here's the final circuit diagram. PF Connections are Green and Light My Bricks component connections in White.
Hiding the Battery
Here was the biggest challenge on this project and I think you can see why in this photo:
The battery is the smallest available but it's still almost the same size as the coal tender itself! We also need to hide the SBrick and lots of wires.
The only logical approach was to rebuild the coal tender to make it twice the size. As we only had the two small Hogwarts Express branded panels we used both of these on one side and build the back of the tender in plain red and black bricks.
Here's how we started - note that the SBrick is powered from underneath whilst the PF Battery connector is on top. Building the front wall (where it will face the engine) we left a gap at the top big enough for the fat PF cable to go through, Shown here with a helpful yellow arrow:
Once assembled it looks pretty decent we think.
Just visible on the top you'll see a small opening on the left so you can turn the battery pack on and off. The 1x2 Plate with Handle which was on top of the original coal tender fits nicely here to disguise the switch.
The End Result
This was a fun project and the result - a fully remote controlled Hogwarts Express - was great fun to play with.
To integrate all the parts we used it would have been great to get a second Hogwarts Express set. Then we could have the battery inside one passenger car (Maybe replacing the windows in the front half only, like for a dining car or similar) and the SBrick inside the coal tender. This would have made the wiring easier and also left us a neater looking train.
All in all this worked really well and the SBrick was great to control both our Light My Bricks lights and the LEGO Power Functions components too.
This blog wouldn't be complete without some videos of the train in action so here you go!
Until next time - happy building!