you have to pick the the from data sheet.

switch(results.value)

  {

    case 0x70: Serial.println("Menu/Exit");
    digitalWrite(13, HIGH); // here you can put on or off your motor
     break;

Got it???

What do you want to do?

this is a good solution

I did a project that:
1-Make a calculation of total power of 4 x 180 watt cell then is exported to a excel 
2-swicht the cell form all in parallel to 2 in series in parallel with 2 in series when the sun is not enough
for increment the output power

The circuit that DVDdoug gave you will make a lot of distortion .If you want to make a true Class A amp yo have to use other circuit
1- Use capacitor in the input to avoid dc got direct to  transistor.
2 Use any trick to avoid DC go into Speaker.

Ok the easy way is to use Darlington transistor connection for example TIP 140

 

there are several forms to do it, this one is very simple way
Check the diagram

1_ test the arduino side: Check connecting the pin2 to something else like switch and see if you can read it
connect if to 5 v and then to 0.

2- Check the flow sensor: put to water circuit and check volts between yellow and black cable.

Why do you send the diagram?

how to use 8 ping as full 8 bit ports in arduino mega?

i did some similar using normal TTL gate and no problem, i used a normal SN7414 with no problem,but i used only 4 of the 6 available , maybe you have to use one with less consumption  like the SN74HTC14 in SO14 package

check this    http://www.sparkfun.com/products/8745,but you can use a simple npn transistor with a clam diode in the base

for help you send the full diagram for only one channel with the diodes

You have to use something like this where R2 is the circuit you want to switch on and off but
1- Transistor must be powerful enough  to drive your circuit, you have to know the amount of current you need
2-The base current must be limited to 20ma so the transistor must have enough hfe ( current gain) for do that
3-For full help i need to know how much current you need and the input voltage

 see here      www.jameco.com/ mybe one fit for you