Trampolino

Believe it or not, the most complicated part of the project is to insert a straw upside down into an empty plastic bottle.

Can you do that?

I have heated up the bottom of the plastic bottle with the tip of a how glue gun and penetrated the bottle with the straw when there was enough heat.

Make sure there is no leak.

• Fill the bottle with some water
• Close the bottle with its original cap.
• Place a finger on the straw.
• Squeeze the bottle! no water should come out.

The next step is binding the arm of the servo motor to the straw. I've used some tape to do so.

Trampolino requires a "liquid passing sensor" at the tip of the straw. This is made up of a couple of wires that close a circuit when the liquid passes through the tip of the straw.

Use some tape to bind the two wires at the end of the straw as shown below:

You can optionally mount a led that will turn on to indicate whether the liquid is flowing. Just extend the ends of the led with two wires and bind it to the end of the straw with more tape.

Start by connecting the +5V and GND pins of the Arduino to the breadboard. Extend these connections to the other side of the breadboard as shown. Connect three push button input circuits. The push buttons are supposed to be far away from the breadboard, so you would need to connect long cables to them. In my project I've used buttons that looks like this, and connected each of them to the breadboard though crocodile wires.

Connect the servo motor and the capacitor as shown. The capacitor can fit directly into the breadboard actually (it looks like that in the picture just for clarity purposes). Note that the polarity of these connections is important.

This is our liquid passing detection circuit. The two floating cables must be soldered or connected somehow to the wires at the tip of the straw we have prepared at step 4 of the previous section. I have no other particular note about this step.

Connect the led we have prepared at step 5 of the previous section to the breadboard. This step is optional. As you can see I'm using the pin 13 of the arduino, which is already connected to a small led on the arduino board. If you skip this step, you won't have feedback about liquid passing through the straw at the tip of the straw.

You don't need to solder 12 wires from the display to the breadboard if your display has headers. If this is the case, just plug it on the breadboard as the very last step of this tutorial.

Finish up connecting the display. As you can see, there are two mini circuits here.

The potentiometer can be used to tune the backlight of the led display.

The on/off switch is used to turn on and off the backlight of the display. I just don't like to have lights on if I'm not using a device... but if you don't mind you can connect that resistor directly to +5V and skip the switch connections entirely.

Note the curve cables at pins 29 and 30 of the breadboard. They are curve because a display with headers may sit over them (see previous step).