Electronics-Lab.com Blog

Technology in the Appalachian Foothills: DHT22 Temperature/Humidity Sensor. [via]

Here’s a little something I cobbled together from a DHT22 Sensor, an Adafruit DC BoArduino, and a 3-digit LED display. More to come!

DHT22 Temperature – Humidity Sensor - [Link]

s p e x writes… [via]

Dear Adafruit Industries,

I just wanted to let you know how excited I was to get my BMP085 prior to the hurricane reaching northeastern Massachusetts.

I rigged it up and logged samples for about 24 hours, you can see my
jury-rigged Arduino, the sensor, and the data.

Thanks so much for the neat device, the great instructions and the sample Arduino library/code. Setup was a breeze! [pun half-intended]

Keep up the good work!

BMP085 Barometric Pressure – Temperature – Altitude Sensor - [Link]

Stian wrote up a great post on his own blog explaining how his project works and how you can build your own control hardware. He writes: [via]

A professional sous vide setup costs at least >$1000, so it’s a bit out of reach for the normal home cook – except for the DIYers.. It’s not that hard to build yourself if you put your mind to it. What you need is the following components: Water bath with a electric heater.

1. Some method of circulating the water.
2. A way of accurately regulate the heater based on water temperature
3. Some way of plastic bag packing you meat.

Water bath with heater is easy enough, there are tons of items out there that does this – slow cookers and rice cookers for example. I use a simple rice cooker, the cheaper/simpler the better (we’re going to cycle it’s power on/off, a dumb cooker will behave better facing a power loss). To circulate the water I use a simple ebay aquarium pump (payed $9.90 for mine). To pack the meat in airtight bags you can either buy a cheap vacuum-packer or simply use zip-lock bags (fill your sink with water, add meat to bag, submerge bag in water but keep the opening above waterlevel – pressure from the water will press out all the air, seal the bag..)

SousVide-O-Mator Schematic and Discussion - [Link]

Ruijc writes:

The sensor used for sensing temperature is the famous LM35DZ. This sensor is capable of measuring temperatures from 0ºC up to 55ºC and it’s very reliable.

The microcontroller used was once again the 16F88 from microchip.

Simple temperature meter - [Link]

Stian made this awesome sous-vide temp. controller, which he calls the “SousVide-O-Mator”. Built around an ATMega328 with the Arduino bootloader, it uses a DS18B20 temp. probe to monitor the temp, a 20×4 LCD to communicate with the user, and a solid-state relay to switch the rice cooker on and off. It also features one of the neatest, cleanest stripboard layouts I’ve ever seen (style counts!). He writes:

My brand spanking new homemade Sous Vide controller (PID controller for cooking). By connecting the relay to my rice cooker and putting the probe and a small aquarium pump inside I’m able to very accurately control the water temperature..

This is basically a heating immersion circulator as used by some fancy restaurants – readily made equipment cost in the range of $1000.. So I made one myself on the cheap (controller + rice cooker + water pump). This can be used to cook meat to perfection

Perfect for Sous Vide cooking! ( For more information about Sous Vide: http://en.wikipedia.org/wiki/Sous-vide )

Source code is available at bitbucket. Nice work, Stian! [via]

SousVide-O-Mator - [Link]

RasterWeb! Logging the temperature and humidity… [via]

Last November one of the Arduino-based projects I started working on was a temperature logger for the office. With winter coming up I wanted to see just how cold it got. (The office is in a converted attic, and the heating and cooling leaves much to be desired.)

I picked up a TMP36 – Analog Temperature sensor and got it wired up and wrote some hacky perl code to read the data and log it. I never really got it out of the experimentation stage, and ended up pulling the Arduino out for another project. (Isn’t that often the case!?)

So last month when Adafruit came out with the DHT22 temperature-humidity sensor I figured I should grab one, and maybe I’d get around to finishing the project.

My temperature (and humidity!) logger is still not done, but I did whip up something to run this week while Wisconsin is having a heat wave. The office has a window air conditioning unit, but it only runs when someone is in the office. When no one is there, it gets hot. How hot? Well, now we know….

Logging the temperature and humidity - [Link]

Shawon Shahryiar (from Bangladesh) describes in this project about the HSM-20G sensor and its interfacing with the Atmega8 for measuring the ambient temperature and relative humidity. HSM-20G is an analog sensor that converts the ambient temperature and relative humidity into standard output voltages which can be measured through the ADC channels of Atmega8. With the use of the calibration curve provided in the datasheet, these analog voltages can be converted back to the temperature and relative humidity.

Atmega8 + HSM-20G to measure the relative humidity and temperature - [Link]

ladyada.net writes:

This tutorial is for our new BMP085 Barometric Pressure sensor. We show how to wire it up to your microcontroller, read the current pressure and temperature from the chip. We also show how to calculate altitude and weather-corrected altitude.

The BMP085 is a basic sensor that is designed specifically for measuring barometric pressure (it also does temperature measurement on the side to help). It’s one of the few sensors that does this measurement, and its fairly low cost so you’ll see it used a lot. You may be wondering why someone would want to measure atmospheric pressure, but its actually really useful for two things. One is to measure altitude. As we travel from below sea level to a high mountain, the air pressure decreases. That means that if we measure the pressure we can determine our altitude – handy when we don’t want the expense or size of a GPS unit. Secondly, atmospheric pressure can be used as a predictor of weather which is why weathercasters often talk about “pressure systems”

BMP085 Sensor Tutorial - [Link]

The TC74 chip is a serially accessible, digital temperature sensor from Microchip Technology that measures the surrounding temperature through its onboard solid-state sensor and provides it in an 8-bit digital word. This tutorial from Embedded Lab describes in detail about the TC74 sensor and its communication interface through an experiment that uses a PIC microcontroller to read the measured temperature from the sensor.

How to use Microchip’s TC74 sensor for temperature measurement - [Link]

A new MEMS device from Texas Instruments promises to make non-contact IR temperature sensing much easier and less expensive than existing methods. The TMP006 is a complete single-chip, passive IR temperature sensor with integrated MEMS thermopile, signal conditioning circuitry, 16-bit ADC, local temperature and voltage references, and both I2C and SMBus digital interfaces, all in a chip measuring 1.6 x 1.6 mm. [via]

MEMS device revolutionises non-contact temperature sensing – [Link]