Brickduino (2. Parallel Connector)

This instructable is part of the "Brickduino" series. [Brickduino 1. LED]

- I expect that you did the Brickduino LED before you start with this instructable -

Mainly this instructable is the same as the Brickduino LED! So if you want to skip all the steps that are the same than jump directly to step 6!
To light more than one "Brickduino LED", I can simply stack them together. Than they are connected serially and shine half as bright. To keep the full brightness I need to connect them in parallel to each other. I can do this with the "Brickduino cable" but there must be an easier, and nicer way.

Using the G-code and jigs from the previous Brickduino instructable, it must be really easy to make this connector brick.

(To make it a little bit more logical, I'm going to swap the colors on this connector brick. I should do this on the cables also)


Paralles vs Serial

The easy explanation:
When you connect two lights in series, they divide the voltage in half.

For example:
A serial connection
I start with 5V from my Arduino. When I stack two LED's on top of each other they will be in series and will both have 2.5 volt to try to burn. Normally they need 5 V so they will only burn very pale or not at all.

A parallel connection
To give them both 5 V, we need to put them next to each other and connect the top connectors of both bricks and the bottom connectors of both bricks.
Now they will keep the full 5 V. (now they must share the amperage)

In this instructable I want to make the connectors for the tops and bottoms of the LED-bricks.

LEGO:

• 2x2 red bricks
• 2x2 black plates

Other stuff:

• M2.5 x 5 mm bolts
• M2.5 nuts
• 0.5 mm copper plate
• some electrical tape
• some small wire

Tools and stuff:

• The LED's, jigs and G-code from Brickduino 1
• Needle nose pliers
• Wire cutter
• Small screwdriver
• Phillips head screwdriver
• Drillpress (it might also be doable with a hand drill)
• Drills: 2.5 mm, 4,5 mm, 5 mm, 5.5 mm an old 8 mm wooddrill
• A CNC is helpful, but small files might also work
• Super glue
• Grinding wheel or power sander

The connector brick will have two parts, like the LED-brick has. The top part will be a red 2x2 LEGO brick and the bottom part a black 2x2 LEGO plate.

The top part:

• Like with the LED-brick we need to drill a 2.5 mm hole in the middle of the studs. We choose two studs across from each other. Your drill will find his own way when you drill from the inside out.
• I prepare an old 8 mm wooddrill to drill out the stud on the inside of the brick. I grind off the point of the drill until it is totally flat.
• Drill away the stud on the inside of the brick with the prepared 8mm drill. This must go really easy.
• Drill the two studs with the 2.5 mm holes in them away with a 5.5 or 6 mm drill.

To finnish of the top, we need to add the nuts and bolts.

To make the nuts fit, we need to grind two sides off.

For the bottom part I use a black 2x2 plate.

I make the slots in the bottom plate in my CNC, using the "jig" and G-code from the Brickduino LED. You could also do this with a small file.

This video is from milling the bottom plate for the Brickduino LED, but it will be the same for this plate, only using a black plate instead of a red one.

Also the bottom connectors are made the same way as for the LED brick.

I used a 5 mm wide, 0.5 mm thick strip of copper to fold the bottom connectors.

See the drawing on how to fold the strip.
To make this also easily repeatable, I also made a jig for this.

You can also use needle-nose-pliers:

• Cut the strip to a length of 30 mm
• Fold up the last 1.5 mm on both sides
• Fold up again 4.5 mm from both folds
• Fold down 3.5 mm from the last folds
• Fold down 2.5 mm from the last folds

If everything went well, you ended up with something that looks like the pictures.

• Now just push the things in the slot that you made in the 2x2 plate.
• Bend out the two little contacts with a small screwdriver and you are sorted.

Now put it all together.

The top brick:

• Measure enough wire to make an ellipse shaped ring that will fit diagonally in the brick
• Cut the wire
• Put the wire inside the top brick and make sure that  it is around the two holes
• Put in the bolts from the outside
• Get the nuts on the bolts (you might go nuts trying this)

The bottom plate:

• Wrap a piece of wire around the two connectors (the part that will go inside the brick)

It doesn't really matter how you wrap the wire around the connectors, al long as they are surely connected. It might be even better to solder a piece of wire to the connectors.

Joining the parts:

• Put a piece of insulating material inside the brick. (I used a piece op plastic packaging, but you can use electrical tape if you have it)
• Put the bottom plate on the top brick
• Test if the two top connectors make contact
• Test if the two bottom connectors make contact
• Test if the bottom connectors are isolated from the top connectors
• Glue the bottom on the top (be careful with super glue. It will glue you to the table if you don't respect it)

FINISHED!

Now we can easily connect the two Brickduino-LED's in parallel by simply using the Brickduino-connector-bricks we just made to connect them next to each other.

The color-coding also makes more sense now: Simply connect red to red and black to black. You see on the picture that the colors of the cables are still the wrong side around.