How it works.
The basic circuit design is compiled of two main parts; the power regulator and the communication to the user (display control). Below will describe in detail how each system comes together.
Power Regulator
The power generated from the micro-hydro turbine (MHT) is a three-phase alternating current signal - which is not suitable for charging devices. A three-phase rectifier circuit is required to flatten the signal and convert the output voltage to DC (direct current). This is achieved using D1-D6 in the final schematic shown below.
Power Regulator
LM2596
The power coming from the MHT is not consistent in many situations (inconsistent water flow). Because of this, we use a LM2596 step-down regulator to maintain a consistent voltage to the user. If the input voltage to the regulator is reaches 5V, the LM2596 will output 5V to the USB-A port. If the voltage goes above 5V, the LM2596 will "step-down" the voltage to make sure the voltage to the user remains at 5V.
Display
To ensure the user knows the device is working, a liquid crystal display (LCD) is used to display the output voltage and current. This also helps the user get an idea of how fast their device will be charging. The LCD is controlled with an Arduino Pro-mini. Analog pins connected to the output read the data to output on the LCD.
Starting with an initial project I found online for creating a hydro-turbine power generator, some adjustments were made to make the circuit more complex. The picture to the left shows the basic circuit plan to use an Arduino to run a display that will show how much voltage the turbine is actually producing while it is outputting power.
The final circuit schematic is shown to the left. The initial idea to use diodes as an output indicator (as shown above) was scratched and replaced with an Arduino Pro-mini that runs an Liquid Crystal Display (LCD) to provide a digital display to the user.
The printed circuit board was designed using the schematic pictured above. The thicker traces shown were added due to specifications suggested by the LM2596 datasheet. The board was kept down to a size that is portable for the user.
The code to the left shows what the Arduino is doing to control the output on the LCD. The LCD is coded to only turn on for a 8 seconds to preserve power. The goal is to output as much power to the user as possible at any given moment.
The reset pin is used as an "ON" button for the screen. This allows for less external parts and reduces the on time for the Arduino.