praveen @ circuitstoday.com build a Digital thermometer using arduino and LM35
This article is about a simple three digit digital thermometer using arduino. Range of this thermometer is from 0°C to 99.9°C. There is also a provision for displaying the temperature in °F scale. Three terminal analog temperature sensor LM35 is used as the sensor here. LM35 can measure temperatures between -55°C to +155°C. The supply voltage range is from 4V to 30V DC and the current drain is 60uA. The LM35 is available in TO-92 package and it is very easy to use. The output voltage of the arduino increases 10mV per °C rise in temperature. That means if 25 °C is the temperature, then output voltage of the sensor will be 250mV. Circuit diagram of the digital thermometer using arduino and LM35 is shown in the figure below.
Digital thermometer using arduino – [Link]
praveen @ circuitstoday.com posted a project on a Temperature logger using Arduino:
This project is about a simple USB temperature logging system using arduino uno and the serial monitor function in the arduino IDE. The system monitors the temperature every 2 seconds and shows it on the arduino serial monitor. The temperature is shown in °Celsius and °Fahrenheit. The system is interfaced to the PC through the USB port. LM35 is used as the temperature sensor.
LM35 is three terminal linear temperature sensor from National semiconductors. It can measure temperature from-55c to +150C. The voltage output of the LM35 increases 10mV per degree Celsius rise in temperature. LM35 can be operated from a 5V supply and the stand by current is less than 60uA. The pin out of LM35 is shown in the figure below.
Temperature logger using Arduino – [Link]
rahulkar @ instructables.com writes:
This is a complete DIY project which requires a handful of components such as the ATtiny 85, LM35, MAX7219 and a couple of resistors and capacitors running off a regulated 5 V supply.
Temperature Measurement Range : 0 to 150’C / 32 to 300’F
Controller: ATtiny 85
Display type – 4 digit multiplexed 7 segment display (Common Cathode type)
Programming Language: Arduino
The setup can display both in Celsius and Fahrenheit. By default the temperature is shown in Celsius but can be toggled to display in Fahrenheit using the push button.
7 Segment Digital Thermometer using ATtiny 85 – [Link]
This simple project is a digital thermometer using LM35 sensor and Attiny26 mcu to read the sensor value and display it on the LED display. LM35 output is amplified by 11 so can be read by mcu internal ADC. The hardware design files and firmware source code are available on the project’s page.
The sensor section is composed of LM35, OPA344 and some passive components. The LM35 is a precision temperature sensor that outputs 10mV per °C. Therefore, LM35 will output 0.25V or 250mV if it is measuring 25°C. The OPA344 is an operational amplifier that is configured as non-inverting amplifier with a gain of 11. The gain of OPA344 is set by R15 and R16. The OPA344 is used to multiply the voltage output of LM35 by 11. So, the output of OPA344 is 2.75V if the output of LM35 is 0.25V. R17 and C6 serves as a low pass filter for the output of OPA344. The values for R17 and C6 were arbitrarily chosen but for optimum performance, these values must be carefully chosen.
Simple Attiny26 based LM35 digital thermometer – [Link]
Tushar @ embedds.com writes:
In this new tutorial, we will be interfacing a LM35 based temperature sensor with ATMEGA32. The 3 main types are thermometers, resistance temperature detectors, and thermocouples. All three of these sensors measure a physical property (i.e. volume of a liquid, current through a wire), which changes as a function of temperature. In addition to the 3 main types of temperature sensors, there are numerous other temperature sensors available for use.
Interfacing LM35 to ATMEGA32 – [Link]
At the heart of this circuit is a precision integrated temperature sensor, LM35 (IC1), which provides an accurate linear and directly proportional output in mV, from 0 to +155 degrees C. Designed to draw a minimal current of its own, the LM35 has very low self heating in still air. Here the output of the LM35 is applied to the non-inverting input of a comparator wired around a CA3130 opamp (IC2). A voltage divider network R3-P1 sets the threshold voltage, at the inverting input of the opamp. The threshold voltage determines the adjustable temperature trip level at which the circuit is activated.
When the measured temperature exceeds the user-defined level, the comparator pulls its output High to approx. 2.2 V causing transistor T1 to be forward biased instantly. T2 is also switched on, supplying the oscillator circuit around IC3 with sufficient voltage to start working. The 555 set up in astable mode directly drives active piezoelectric buzzer Bz1 to raise a loud alert. Components R7, R8 and C4 determine the on/off rhythm of the buzzer.
Overheat Detector Alarm – [Link]
Probably, some of you have tried buying cool but cheap products from Ebay. Like some of you, I also have bought items from Ebay several times already. One of the items that I got from Ebay is a small ENC28J60 based ethernet module.
As you can see from the image above, the ENC28J60 module is very small. The PCB is more or less one-inch square which is almost as small as the included ethernet jack.
Simple Sensor Webserver – [Link]
A digital multimeter is a very useful instrument that combines several measurement functions in one unit. A typical multimeter includes features of a variable-range ohmmeter, voltmeter, and ammeter. Some of them also include capabilities of testing diodes and transistors. In this article, I am going to talk about a technique of adding thermometer feature to a regular digital multimeter. The technique is very simple and uses one temperature sensor along with two resistors and a DPDT slide switch.
Add a thermometer to your digital multimeter – [Link]
There are quite a variety of active analog temperature sensor ICs that provide an output voltage proportional to the temperature. They usually don’t require any external calibration and signal conditioning, and as such their output can be directly fed to the input of an ADC for digital processing. A few examples of such sensors are LM34, LM35, TMP35/36/37, and MCP9701. If you are having any trouble using any of these sensors in your project, here is a quick way to test if your sensor is working or not.
Testing active analog temperature sensors with a multimeter – [Link]
I designed this version in the need of a thermometer for my room, built in a small pack and easy to control. The hardware is designed on a way so that the pcb can be wall mounted. At the top side of the device the PCB extents giving space for two keyhole type holes which are able to keep the device mounted on the wall. The LCD display plugs at the front side of the PCB, covering all the electronic components and giving a compact design view. The user can interact with the device using the left side switch button. The design includes a 6-pin header which gives connectivity for UART (RX,TX,GND) and for the external sensor DHT-11 (VCC,GND,DATA). Also there is an ISP-6 pin header which gives the option of on board programming. Finally there is an optional Bluetooth plug on the back side connected with AVRs UART for possible communication to other devices like mobile phones, home automation devices, pc’s or whatever you imagine.
The code is written in C and is well performed in a readable way so anybody can read and modify it. For the LCD driving i have used Peter Fleury’s library.
AVR Atmega8 and DHT-11 Thermometer V2.0 – [Link]