Twittering Washing Machine

[youtube=http://www.youtube.com/watch?v=wkMXpKmRXvU&fmt=18]

If you don’t have at least one twittering appliance in your household, you’re getting behind. The latest addition to the spread is a twittering washing machine. [Ryan] tells us that he kept accidentally forgetting to retrieve his clothing from the washing machine, resulting in smelly mildewy clothes. Now, his washing machine twitters to announce it is done. It also has a sign in the house that displays its status to help him remember. We’ve seen unborn babies and toasters twitter, what’s left? Remember those refrigerators that were supposed to let you know that you’re out of certain food? Why don’t we see a twittering fridge yet?

Parts: I2C Digital Thermometer (TC74)

tc74

Microchip’s TC74 is an inexpensive digital temperature sensor with a simple I2C interface. It has a resolution of 1 degree Celsius, and a range of -40 to +125 degrees. This is an easy way to add temperature measurement to a project without an analog to digital converter. We’ll show you how to use the TC74 below.

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Refillable CO2 Cartridges

co2

For those who use these little cartridges, you know how quickly the price can add up.  [steve] takes us through the process of adding a valve to a spent cartridge so it can be refilled. Over all, it doesn’t seem too difficult, and [steve] offers lots of tips to increase longevity and reliability. It isn’t very often that we show a hack here that doesn’t involve some kind of electronics, so take a break from the resistors and microprocessors for a moment and enjoy.

[thanks Wolf]

Parts: Precision Humidity And Temperature Sensor (SHT1x/7x)

sht11

Sensirion’s SHTxx is a digitally interfaced humidity and temperature sensor. Accurate humidity measurements usually require careful analog design, but the SHTxx moves all that complicated stuff into a single chip. Through-hole (SHT7x) and surface mount (SHT1x) versions are available, we used the surface mount SHT11 with +/-3% accuracy. We’ll show you how to use the SHTxx below.

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Parts: 8bit IO Expander (PCF8574)

pcf8574

Sometimes a project has more sensors, buttons, or LEDs than your microcontroller has pins. The PCF8574 is an easy way to add 8 low-speed input or output pins to a microcontroller. A configurable address lets multiple PCF8574s exist on the same bus, so two microcontroller pins can control dozens of IO pins. We’ll show you how to use this chip below.

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RepRap Motherboard

reprapmb-1

When the RepRap team found themselves pushing the limits of the Arduino, they started looking for alternatives. They found it in the ATMega644P. It has four times the memory and four times the RAM compared to the ATMega168 used in the standard Arduino. It also has 32 I/O pins. They ported the Arduino software to the microcontroller and started producing Sanguino boards. Now that the base design is nailed down, they’ve begun expanding it to their specific purpose. Pictured above is a prototype RepRap motherboard. While the Sanguino is barebones, this board has onboard connectors for all of the RepRap’s motors, so you can just plug it in. It is also designed to support the future Generation 3 electronics. Probably the most interesting feature is the SD card slot. The goal is to eventually have a board that can run the RepRap without a host computer if necessary; it will manufacture designs directly from the flash card.

Parts: 1K 1-Wire EEPROM (DS2431)

1keeprom-450

The Maxim DS2431 1K EEPROM is 1-Wire device that adds storage to a project using a single microcontroller pin. We previously interfaced a 1-wire thermometer, but this EEPROM is slightly different because it draws power directly from the 1-Wire bus. Grab the datasheet (PDF) and follow along while we read and write this simple 1-Wire memory.

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