Friday’s Tips and Tricks: Servo


The servo module is a fun and intriguing module with limitless uses.  Unlike the DC motor that spins continuously, the servo is a controllable motor that can move to exact positions. The servo is what an RC plane uses to pivot the tail.

1.) Swing Mode

The servo module has two modes. The first is swing mode. In this mode the servo swings its arm, back and forth, continuously. Servo motors have a limited range of motion and our module is able to move at  a 145º angle. Build a simple circuit to test the servo module: power + button + servo. Don’t forget to set the tiny switch on the servo module to swing.  We attached a flag to our servo to show our littleBits pride!

When you add a dimmer before the servo, you can control how fast the arm swings.

2.) Turn Mode

The second mode is turn mode. In turn mode, you can control which direction the servo arms point.  The servo listens to how much voltage you give it, and moves to the specific position. As you increase the voltage (electrical intensity), the arm turns clockwise; decreasing voltage turns the arm counter-clockwise.

If you use the simple circuit: power + dimmer + servo (turn mode), the servo arm will follow the turns of the dimmer knob.

We made a motorized camera mount with two servos in turn mode. One servo tilts the camera up and down, using a slide dimmer module; the other servo rotates the camera left and right with a dimmer module.

3.) Servo + Pulse

By using the pulse module, you can mimic the swing function while still in turn mode.  With the screwdriver, adjust the pulse module to change the speed of the swing

If you think the waving flag above doesn’t fully express your love for littleBits, try this.

Here is another example of using the servo + pulse combo.

4.) Servo + Pulse + Dimmer

For more control you can add the dimmer to make this circuit:  power + dimmer + pulse + servo (make sure you’re still in turn mode).  The pulse module sets the servo’s speed, and the dimmer determines the range of motion.

5.) Servo + Inverter

A servo points to the left when the voltage is low, and points to the right when the voltage is high. What if you want it to act the opposite? Simply add the inverter bit!

In the Waving Hand project there are two servo bits used.  He’s normally a “hello hello” man, but when you put an inverter module between the two servo bits, he becomes a “no no” man.


6.) Embedding a Servo Motor

A body of the servo motor can be easily embedded. Cut a rectangular hole that measures  ½” wide and 15/16” tall to place the body of the servo motor in. There are also screw holes for easy mounting. 3mm or ⅛” machine screws work nicely.

 embedding servo1

7.) Servo Attachments

The servo module comes with 4 different types of arms. Depending on your project needs, you can switch these arms or reorient them to suit your purpose.  To change arms, remove the screw and put the new arm on.  Don’t forget to replace the screw!

 head change1

The arms have holes for connecting to other materials.   There are multiple holes to choose from, so which do you use? The closer the hole is to the center screw, the easier it is to move, but the less distance it will travel.  The further away from the center screw, the more it will move, but the harder it is to move.  To move a heavier object, try attaching it closer to the center.  The further you want to move it, the further away from the center your object must be, and therefore, the lighter your object needs to be.

This relationship of force and distance is called torque.  Read more here.


8.) Physical Control of Bits

Usually you control the modules by adjusting them with your own two hands, but why not let the other modules do all the work? Our friend Northy thought it would be really nice if she could change the color of the RGB LED module or the speed of the blinking light by pressing a button or turning a dimmer instead of turning the purple screwdriver herself. To do this, she used the servo!  Check it out below.

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