Zener diode technique for Arduino signal control

Zener diodes are reverse biased, a trait which allows for current to flow in the opposite direction of the standard forward direction, whence the zener breakdown voltage had been reached. This useful effect, appropriately deemed the avalanche effect, allows for current to flow "backwards" at an increasing rate as more voltage is applied, as shown in figure. 1.

                         Figure 1

With an Arduino there is a large variety of uses. For example if we wire a battery into the arduino and diode as a circuit in the following way:

1. The negative end if the battery to a GND pin).

2. The positive end if the battery to a digital pin( depends on the board and application). This now goes to the anode(black side) of the zener diode.

3. The orange side(cathode) of the Zener diode is wired to the load usually =5V and =battery current+arduino current.

Now choosing the diode is critical. Arduino digital HIGH( which is traditionally the most produced out of an Arduino pin) reads out at 5V*(presuming you have the pin constantly on during measurement because Pulsing voltageay appear as lower voltage in a traditional multimeter). Therefore we want the zener voltage to be less than 5 volts, the exact choice depends mainly in how much current the load require. Now the arduino can power and control larger Amp devices!