Introduction: How to Make a RockBand Guitar Playing Robot!

For my first instructable...

What can I say, I love to drum away on the rockband set but it's rare that I have someone to play with me; maybe I need more friends, but out of my seemingly lonely life(jk) comes a pretty cool intractable. I have designed a robot that plays the Rockband guitar for me and I'm sure it would also play Guitar Hero. When I got the idea I had no idea if I could do it or how it could be done. I literally spent the entire contest duration learning and working toward this instructable. I made this instructable because I hope many others build this project and learn from and enjoy it as much as I have.

I have divided this instructable into two construction parts and a final closing.

1. Constructing the mechanical parts
2. Constructing the electrical parts and combining the two

Let's get started!

Quick preview:

Step 1: Items You Will Need...

1/8 dowel rod for axels, metal works best
4 x 6 Base for project, wood or plastic (I used plastic as show in pic with holes drilled)
12V DC adaptor (any old DC adapter will work, just cut the cord to connect it)
Balsa wood for arms and pillars 3/8 x 3/8 x 36 (1.00 at any craft store)
Small screws
Small springs (5.00 at Walmart get a spring assortment) (Quantity 3-5)
A small PC Board (2.00 at RadioShack I used a 276-150) (Quantity 3-5)
12V Solenoids (2.99 ea at  part num: G16829) (Quantity 3-5)
20K Ohm potentiometers (10 for 2.00 at part num: G13736) (Quantity 3-5)
NPN Transistors for switching applications (10 for 2.00 at RadioShack) (Quantity 6-10)
741 Op Amp Integrated Circuits (99 Cents at RadioShack) (Quantity 3-5)
1k Ohm Resistors (1.00 or a pack of a bunch at RadioShack) (Quantity 3-5)
CDS cells ( 2.19 for an assortment at RadioShack) (Quantity 3-5)
Jumper wires if you are building a prototype circuit

The number of electrical components you will need depend on how many color notes you want your robot to play. I strongly suggest starting with 3 and working your way up once you have been successful.

Solder less Breadboard(optional only if you want to build a prototype circuit first, I recommend it)
Phillips screwdriver
Drill w/ drill bits
Saw if you need to cut a 4 x 6 base for your project(you can probably use balsa wood to simplify)
Razor Knife
Tape measure

You will also need your tv, rockband 2 game, xbox 360, and rockband guitar.
You will notice that I actually used my projection screed as I don't have a tv, it will be much, much easier to do on a tv.

Step 2: Part 1 - Construction of the Mechanical Parts

First we will need to build a base for the project.

1. Cut a piece of wood or plastic board that is about 1/6" to 1/4" thick into a 4 x 6 rectangle, it should be rigid.
2. Next drill the holes as shown in th picture

Step 3: Attach the Solenoids


Attach the solenoids to the base, they come apart for mounting, just take the nut and washer off of the solenoid slide the solenoid into the base, reattach the washer and nut. Do this for all of your solenoids.

Step 4: Building the Balsawood Parts

Build the fingers and risers

Use the 3/8" square extrude balsawood stock to make your fingers are risers as shown in the image.

You will need 1 finger for each color note you want your robot to play.

You will also need to make 2 risers to hold the main axel.

Drill all the shown holes with a 3/16" diameter bit.

A razor knife cuts balsawood well.

Step 5: Adding the Fingers

Connect each finger you made with the top section of each solenoid by using a small piece of jumper wire as an axel, run the wire through and bend the ends. The top sections of the solenoid are removable as you can see in the picture(the pieces have been removed from unassembled solenoids)

Step 6: Adding Your Risers

Connect your risers to your base by screwing them into your offset holes on the ends of your base board. The screw goes in threw the bottom of the board threw the hole and screws into the balsawood riser.

Step 7: Add the Axel

Run your axel through the riser, each finger and then the final riser. If you are building a basic three 3 note version of the robot, your project should look similar to the picture shown. You may choose to cut off the extra axle.

Step 8: Almost Done With Part 1!

Now all we have to do is add the springs to the fingers, the springs help the fingers lift back off of the guitar buttons. The other 6 - 1/8" Diameter holes that you drilled in the base are the mounting points to one end of the springs. Bend the spring around the hole to mount that end. Make a hook out of the other end of the spring and hook it into the back end of the finger(where you cut it at 45 degrees) for each assembly. Experiment with different spring tensions until you get the perfect pressure, you don't need much.

Step 9: Add the Guitar

Don't use a wireless guitar because all the extra electronics causes radio interference that prevents the guitar from working properly, I learned the hard way.

Slide the guitar into place, you can clamp the assembly over the buttons it needs to press. You can also screw it or tape it, I just put a clamp on it because mine will not be permanent. Push down on each finger to make sure that they fully push and that the springs pick them back up off of the button when you let go. Make any minor adjustments by sliding the mounting points of the base to the guitar around a bit. You should have no real difficulty.

Step 10: Add the Strummer Solenoid...

Since my version of the robot is not permanent, I used double sided tape to connect the solenoid to the right location and used tape to connect the moving part of the solenoid to the strummer thing. Make sure that the solenoid is in a position where it can pull the strummer all the way until it clicks.

The mechanical assembly is complete!!!

Step 11: Section 2 - Constructing the Electrical Parts

I would like to start this section by saying that I am not an electrical engineer. If you know a better way of making the circuit, use it :P I actually read several books before if figured out how to make this circuit, it is however, of my own design and I am somewhat proud.

If you know how to follow an electrical diagram, go ahead and build the circuit without reading this section of the instructable. If you know NOTHING about electrical except a basic knowledge of soldering, you should be able to build this circuit by following the following (no pun intended) steps.

If you can't solder, there are instructables that show you how to :P

Solenoid 1 is the solenoid at the finger

Solenoid 2 is the solenoid at the strummer
Each circuit built connects to the same place on the strummer. This is so that each circuit will operate the strummer when the finger is operated.

This circuit works by comparing the CDS cell resistance to a base resistance, in this case the trimmer pot. The IC is doing most of the work. The transistors get a signal from the IC when there is a change in resistance(in this case light from the game crossing over the CDS cell), they then allows the full 12v of electricity to flow to the solenoids. Its pretty basic.

Step 12: Closer Look at the Electronic Components

The components from top to bottom are,

CDS Cell(photo resistor)
Spring(how did that get in the picture?)
1k Ohm Resistor
Op Amp Integrated circuit
NPN Transistor(make sure to get ones intended for switching applications)
20k Ohm Trimmer Potentiometer

On the next slide I will show you exactly how to lay out the components on a RadioShack 276-150 board. This is for us non-engineers our there.

Here are some other great resources you can use on instructables.

How to read a circuit diagram:

How to build circuits, building 101:

How to solder:

Step 13: The Electronics - Step by Step

Don't freak out, just follow the steps it's easier than you think!

Read this all carefully and double check when you are done.

We are viewing the board from the bottom, the components rest on the top(opposite) side of the board. The leads coming off the parts get soldered to the board on the back side. Think of the copper tracing on the board as a wire, wherever the copper goes, the electrons will go. (Figure 1)

1. The light green numbers represent the DC power lines from your 12 DC box. Cut the leads and solder the positive where the light green 1 is(positive is usually indicated by a line on the wire) solder the negative side where the light green 2 is. You can now use the available spaces along the copper tracing to connect to when you need V+ or ground. (Figure 2)

2. The red numbers represent the leads of the potentiometer. Lead 1 goes to any available V+ spot on your board(I suggest using the space to the immediate left of the orange 1, photo shows white jumper wire). Lead 2 can just be cut off, I soldered it to the board to at strength then I cut it off. Lead 3 can be bent over to the red 4 position and soldered to the board. This allows power to flow from the red 4 to the black 4. (Figure 3)

3. Integrated circuits, in this case the 741 Op Amp, have a mark on them to indicate direction. Make sure that(from the top of the board looking at the components) the round dot is on the right. Then you can solder all 8 of the black leads into place. (Figure 4)

4. The blue numbers are for your lower transistor. Transistors have to be installed in a particular direction. In this case make sure the flat side of the transistor is parallel to the edge of the pc board. Solder all three of the blue leads into place. The blue 1 goes to one lead of you finger solenoid the other end of your solenoid goes to the ground(anywhere on the copper of light green 2). I did not connect the solenoid leads in the photo, this is to prevent clutter in the photo. I just bent them over to indicate that they go to an external component, I use this technique to stay organized. (Figure 5)

5. The green numbers are for your 1K Ohm resistor. It does not matter which way you install it just run the leads through the board and solder both of the green leads. (Figure 6)

6. The orange numbers are for a jumper wire. We are fortunate to have used this traced board or we would need to have jumper wires connecting all of the numbers we have soldered so far. Just connect a short piece of wire from the orange 1 to the orange 2, make sure to use insulated wires so that no cross contact is made(I used a brown jumper wire) (Figure 7). Add a jumper wire from the black 4 to the ground. Add a jumper wire from black 6 to V+. (Orange and yellow wire shown in Figure 8)

7. The purple numbers are for you upper transistor(closest to the trimmer pot). Again it is directional; connect it so that the flat side is pointing to the opposite side of the board with the RadioShack written on it. Connect the purple 2 to the green 1 by bending the excess lead over to the green 1 on the bottom side of the board or use a jumper wire. Connect the purple 3 to the orange 2 using the same technique. Connect the purple 1 to one side of the strummer solenoid and connect the other solenoid lead to the ground(not shown). (Figure 8)

8. Add long leads to your CDS cell, long enough to go from you project base to the TV you will be using. The grey 7 connects to one end of the CDS cell wire the other side of the CDS cell connects to the V+. One photo shows the connection to the board, the other shows connection to the CDS cell. (Figure 9 and 10)

9. Now that was a mouth full so double check, use the photos as a frame of reference to make sure you did everything right. I still suggest building this on a breadboard first but that will take a little know how as well. You can always check out other instructables if you want. There is ample room left for the clone circuits you will need to build for the other notes. This circuit runs only one note so a 3 note version needs 3 circuits and a 5 needs 5. You can use the same DC adapter and V+ and ground for all circuits.

Step 14: Put It to Use

Ok after that last step your electronics should be connected to your mechanical components. You should have several feet of lead on your CDS cell. The CDS cell is the sensor that will detect the change in light on your TV set.

In the Rockband 2 game widow the "strike" area is indicated by a colored rectangle. Place(tape the face of) the CDS cell just above the upper right corner of the strike area. The oncoming notes are white on the edges, the white is much brighter than the strike area and will cause a change in resistance that the circuit you built will detect, the circuit will push the color key and the strummer. You many need to move the cell around a bit to get it calibrated(timed right). Note the placement in the pics(forgive the quality pics of projection screens are poor) and in my video. In the pic below it's the black spec.

Once you pick a location for the cell you will need to adjust the trimmer pot with a screwdriver to change the resistance to tune in the CDS cell. Turn the pot until the solenoids close, then turn it back just enough to let the release. Now any increase in light should cause the solenoids to close, thus playing one note on rockband. Play around with it until you get the perfect result, its actually A LOT OF FUN when you get to this point. Build the other 2 circuits the same way and you will have a rockband playing robot! Twice more and it will play on expert. Make sure to check out the video to see how it all works.

I focused on showing you how to build one circuit at a time to keep it simple, now run with it!

Step 15: See It Work

The video shows the circuit playing the GREEN NOTE ONLY after calibration. I selected a segment of song that shows the circuit playing the "whammy" note as well, it's pretty cool. The only problem is that I made the video with a digital camera because I don't have a real video camera. The more going on the less the camera would focus so we only get to watch the one circuit in action in the video. Not to worrie you will have yours running in no time :P When I get a real video camera I'll make a high quality video of the robot playing all of the notes.

I hope you enjoy, and happy instructifying!

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