This page is just to give a quick run down of the project for any poor soul that found their way to this site with the intention of reading about an Arduino project in the usual fashion.
Disclaimer: This isn’t an instruction manual to copy, details are for the sake of interest, not reproducibility. There’s a lot of potential fire and electrical hazards involved and I’m bound to forget to mention how I mitigated the threat of at least one of them. Besides that, the project wound up much more expensive than most alarm clocks out there. Save your money, save yourself, save my conscience; don’t try this at home.
Brief:
An alarm clock is to be built using an Arduino Uno, the clock should be capable of gradually brightening a lamp to imitate a sunrise, with the brightest setting reached at 7:30. At 7:30, there should also be a hot beverage prepared to start the day. The lamp should also work as a regular lamp outside of 7:00-7:30 and the current time should be displayed in response to a button push.
Parts:
- 1 x Arduino Uno
- 1 x RTC
- 1 x LCD Display with I2C interface
- 2 x White LED
- 1 x Cartridge Heater
- 1 x Metal Block
- 1 x Wooden Board
- Lots x Lego Bricks
- 1 x 12V Supply
- A fair few x Resistor
- 1 x Stripboard
- 2 x MOSFET
- 1 x Copper Plate
- A Few x Wires
- 2 x Switch
- Lots x insulation
- N/A x Things I’ve Forgotten And Will Add Very Soon
Clock:
The Arduino keeps time by communicating with an RTC module, which is daisy-chained to an LCD display (I2C). To wake the display and show the time, a capacitive touch button is touched. This capacitive sensor is made using a 10MΩ resistor between two pins of the Arduino with an extension from one of the pins to a copper plate. The copper plate is the sensor. The CapacitiveSensor library for Arduino is used.
Lamp:
2 LED bulbs are in parallel and draw current from the Vin pin of the Arduino. The path from the LEDs continues to the Drain pin of a MOSFET (FET hereafter). The source pin of the same FET is connected to Arduino ground pin. The gate pin of the FET is connected to a pulse width modulation (pwm) pin on the Arduino to enable varied gate voltage and brightening of the LEDs. Between the gate pin and pwm pin there is a current limiting resistor. There is also a pull-down resistor between the gate and source pins of the FET to avoid floating states.
Manual control of the lamp is given by a wire going from the 5V supply of the Arduino to a digital input pin, through a current limiting resistor and a normally-open, springed switch (basically a button). The code is arranged to make use of this signal as a means to turn the lamp on and off.
Heater:
The power supply is connected to the heater via a safety switch. The heater refers to a cartridge heater inserted into a metal block to form a hot plate – for use with metal cups. The heater then gets connected to the drain pin of a FET. The gate pin of the FET is linked to a digital pin on the Arduino via a resistor. The source pin of the FET goes back to the power supply, also branching off to the ground pin of the Arduino just to follow best practice – the Arduino and heater share a supply, thus share a common reference anyway. Also there’s a pull-down resistor between gate and source pins on FET.
Casing:
Casing is built from Lego with a wooden board for the top. The board has a slot for the heater which has a thick insulation bed. Lego bricks are ‘missing’ throughout the walls for ventilation.
All electronics are linked together using a stripboard.
Note that this is the first draft of this page. It will be amended and appended to soon, the Arduino sketch (or at least a flow chart and list of libraries used) and a few photos may be included but treat it as just the general gist of the project for now. (Circuit diagrams will of course be first priority in the amends.)
More details are being formulated into “The Project: Basic Rundown v1.1” right now; it will be uploaded soon!
Trysworth Curiosity Company 