Quick to build: Littlebits spinning flower with proximity sensor

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If you’re looking for a quick project that can be done in less than an hour, give this Littlebits spinning flower a try. Liam figured out the circuit and designed the flower himself. The fact that the Littlebits axle on the servo is compatible with Lego makes it ideal for building motorised projects.

First, build the circuit, so that you can test out your sensors, try out different orders of Bits, and make sure it works. Then build the flower and fit the circuit in.

You will need:

• Battery pack with cable
• p1 power bit
• i8 proximity sensor (you could also use a light sensor or noise sensor)
• w1 wire (x2)
• o9 bargraph (optional but very cool)
• o25 dc motor
• 2×1 Lego Technic bricks (x2)
• 12×2 Lego panels (x2)
• 8×2 Lego panels (x2)
• 6×2 Lego panels (x3)
• 6×10 or similar Lego plates to make the base (x2)
• 2x6x2/3 modified plates with studs on side (x2) – part 87609
• 1×2/2×2 brackets (x6) – part 44728
• 1×2/1×4 brackets (x2) – part 2436
• Technic plate rotor 6 blade – part 64566
• Technic bush 1/2 smooth – part 4265c
• Your choice of Lego pieces to decorate the flower

Start by building the Littlebits circuit

It’s best to start by building the circuit for your spinning flower, so you can check it’s all working as expected before you start the Lego construction. Connect your Littlebits in this order:

1. p1 power bit
2. i8 proximity sensor (or light sensor, or noise sensor)
3. w1 wire
4. o9 bargraph
5. w1 wire
6. o25 dc motor

On your o25 dc motor bit, set the slider switch all the way to the right, on the ‘cw’ position. This isn’t anything mysterious – it stands for clockwise, and controls the direction of the motor. If you want to test it later, try sliding across to ‘ccw’, or counter clockwise.

Now, connect your p1 power bit to its battery, and lets test it out.

The proximity sensor detects when something comes close to it. Move your hand closer to the sensor, and then further away. When your hand comes close, the bargraph will light up and the motor will begin to spin. The closer you go to the sensor, the faster the motor will go. Try moving your hand away slowly, and you’ll see the motor slow and the lights on the bargraph slowly reduce.

If it isn’t working, there are a few things you can try:

• Remove the wires from the circuit, and connect the sensor, bargraph, and motor directly together. This will tell you if there’s an issue with your wires
• Switch the dc motor to the other direction. It may have been sitting in between two positions.
• Change the battery. The motor puts a bit of load on the battery, so an older battery might be struggling.
• Swap the sensor for another bit, and see if the bargraph lights up. If it does, try reconnecting the sensor. It might not have been connected properly.

Build your spinning flower structure

Take the two base plates, and set them side by side with a two-dot gap between. Use the 2x6x2/3 modified plates to fix them together, placing the modified plates evenly in the centre. Make sure the side studs are facing outwards. Fix a 6×2 plate down the centre of the modified plates to make a flat platform.

Build each side of the stem with the 6×2, 8×2 and 12×2 plates, with each piece fixing to the inside of the piece below. That will make the opening at the base wider than at the top, and gives more space for the Littlebits circuit.

Now, add the brackets that will hold the Littlebits circuit in place. Keep the final two of these brackets aside. At the front, on the lower connection point, use a 1×2/1×4 bracket either side. It still holds the Littlebits in place, but doesn’t cover up the cool circuit you’ve built. At the back of the flower stem, fix 1×2/2×2 brackets, just at the bottom of each plate connection point. There will be two on each side of the stem.

Now, at the top, fix your 2×1 Technic bricks to the underside of the Littlebits motor, with the dots facing outwards. If you’re like Liam and have some random 3rd party bricks hanging around, try those, as the official Technic bricks are a very tight fit.

With the bricks fixed to the motor, fit them into the top of the flower stem. If you need extra stability, try using some rubber bands or masking tape.

Fit the Littlebits circuit to the flower structure

Now you’re ready to fit the Littlebits circuit into place.

Slot the bargraph Bit into place in the middle of the stem, with the flexible wires coming in from the bottom at the front, and out the top towards the back. Now, grab those last two brackets, the 1×2/2×2, and fit them to the front of the stem at the same height as the back upper brackets. They should approximately line up with the connection between the bargraph and the outgoing wire.

At the back, rest the dc motor Bit on the Lego base plate. At the front, line up your proximity sensor right in the centre, with the power Bit towards the left.

Decorate your Lego spinning flower

To create your flower, add decorative Lego pieces to each spoke of the 6-blade rotor plate. The small yellow bush will be going in the very centre, so make sure to leave space for it. You could use contrasting colours for extra interest, or some rounded shapes for petals. The choice is yours!

When you’re happy with your flower, it’s time to fit it to the motor. Slide the centre of the flower onto the axle on the motor. Then, use the yellow half-bush to secure it in place.

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Now, test out your Littlebits spinning flower!

It’s time to get your flower spinning!

Turn on your power Bit, and slowly move your hand over the proximity sensor. Watch as the bargraph lights up the stem of the flower in green, and your flower starts to spin. To speed it up, move your hand closer to the sensor, and to slow it down, try moving further away.

Other fun projects

If you liked this, why not try out a Littlebits inchworm too?

For more Lego projects, we’ve also got a dancing crab, a monkey, and another inchworm.

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