The Start


Hi, What and Why

Plug it in

Rule number 1

Water Sensor

Sound Sensor

Joystick

Tri Colour LED

RTC (Real Time Clock) DS1302

RTC (Real Time Clock) DS3231

Matrix LED step 1

LCD

Stepper Motor

LCD revisited with PCF8574T

Humidity Sensor

Shift Register

RFID tags (RC-522)

7 Segment display

Ultrasonic distance sensor

5V regulator

analogRead and analogWrite

Wiring an Array of Switches

The next step


Other things I have bought

Infra red and Processing

Programming a separate arduino chip

Creating your own PCB

L293D for a DC motor

4 digit 7 segment display

Starting with motors

RF433 Wireless Comms

Sort a character array

More stuff


I2C devices (SDA,SCL)

I2C scanner

SPI devices (MOSI,MISO)

HMC5883L Compass

MMA7361 Accelerometer

Added projects


Message Display System

4WD robot car
4WD robot car II

4WD robot car COMPLETE

MP3 Player

5V regulated power supplies

When you are testing circuits next to your PC, of course the easiest power supply comes from the USB port.

However, when you create a standalone project, you need a different power supply. The Arduino can be powered in 2 main ways. Either a regulated 5V power supply into Vcc, or, into Vin, an unregulated power supply between 7-12V.

One of the easiest methods is a 9V battery through a LM7805 voltage regulator. Note that a 9V battery supplies about 500 mAH, so will not last very long. You can experiment with 6 x AA (or AAA) battery holders as an alternative.
When I was creating a robot car, I bought a 3300 mAh rechargeable battery as my final solution.

As a quick comparison, an arduino pin will supply up to 40 mA. A 9V battery contains 500 mA hours. Quick maths says that a 9V battery will run a circuit with a small component for about 11 hours. (500 mAh / 40 mA). More components - fewer hours.

Pre-built or self-build 5V regs can be purchased cheaply (less than £5) on EBay, search for "5V regulated power supply".

A purchased L7805 5V regulator. 4 diodes across the input allow for AC to be used as an input as well as DC. L7805 5V regulator

They can also be easily built at home; the circuit is easy.

5V regulator circuit diagram and components. L7805 circuit diagram

Note: in this home-built 5V reg (below) that the circuit board has been cut underneath (use an electric drill bit, rotated by hand).
2 breaks in the stripboard are required, one for the diode and one for the L7805 input/output pins.
There's a photo at the page bottom.

A home-built 5V regulator. I will monitor the temp of the L7805; large current will cause it to warm, so a heat sink would be needed. home built 5V L7805 regulator

One of the most useful components ever: plug in an adapter (from laptop, printer, scanner, etc), and get the voltage out easily into 2 wires. Make sure you buy the correct size ! These are listed as EU 2 PIN UK 3 PIN DC 12V 2A Power Supply /Charger / Adaptor Plug on EBay (UK). laptop adapter into 2 wires

Below is a perfect 5V regulator (for this project !). A 9V battery, with 9V unregulated outputs before the L7805, and multiple regulated 5V outputs on the other side.
Here, the 5V supplies an arduino pro mini, a joystick, and an RF433 wireless transmitter.

5V regulator with both unregulated and 5V regulated outputs. Perfect 5V Regulator

The underside of the stripboard is cut, using a drill rotated by hand, to break the circuit in the appropriate places. In this case, a cut is required below the diode and below the L7805 input and output pins.

The underside of the stripboard. Cut the stripboard