Electronics-Lab.com Blog

TrH Meter is a DIY microcontroller-based indoor thermometer plus hygrometer that displays temperature (F/C) and relative humidity on 4 seven segment LED displays which adjust their brightness level according to the surrounding illumination. The displays are 1 inch big, emits bright yellow color, and are readable from more than 50 ft away. It consists of a closed loop system that continuously assesses ambient light condition using an inexpensive light-dependent resistor (LDR) and uses that information to adjust the brightness of the display. The DHT11 sensor is used to measure temperature and relative humidity. The microcontroller used in this project is PIC16F688, and it runs at 4 MHz internal clock. A separate display driver chip (MAX7219) is used to control and refresh the display data on the seven segment LEDs. A 3-position slide switch controls power ON/OFF and Fahrenheit (F) or Celsius (C) scale select for temperature display. You can now preorder the project kit for a discounted price of $25 on Tindie. You will receive a preprogrammed PIC16F688 microcontroller in the kit.

TrH Meter project kit is now available for preorder on Tindie - [Link]

This temperature measuring project has a variety of range from -55 to +125 degree centigrade indicating on four common anode seven segment display module.The project measures an accurate temperature value point to point.

The main sensing part of the project is the semiconductor DS1820.It is based an one wire protocol device manufactured by Dallas semiconductor comes in different resolution such as DS18 S20(9-bit resolution), DS18B20 (12-bit resolution) etc.A microcontroller(AT89C2051) controls whole circuit function like receiving the serial data from DS1820 and converting the value for displaying the seven segment module.

DS1820 Digital Thermometer - [Link]

Reka Kovacs writes:

We are building an ArduSat (according to the Cubesat standards a satellite 10 cm long at the edges and 1 kg or less), on this satellite we would put up to 5 Arduino’s and plug in 50+ sensors into them as well as 2 optical and 1 IR camera. Once the satellite is on orbit we would then give access to the general public/citizen scientists to the payload ( Arduinos, sensors and camera) to upload their own scientific experiments. We plan to capture the attention of the DIY community, hackers and makers, amateur astronomers and in general those interested in space exploration and the next frontier.

Sensor wise we have so far magnetometers, tachometers, plasma sensor, photometer, thermometer, pressure sensor, space radiation (bitflip) sensor, Geiger counter and 2 optical and 1 IR camera etc.The idea is that people can rent scientific packages for a week, during the week they run their experiment we will send data constantly back to them to analyze. Imagine general public, including teachers having access to experiment platform in space for a couple of hundreds of dollar and they analyze data and engage students, friends etc., it could revolutionize the way people see space. Also we are looking for feedback from people interested in the project. We want to hear their ideas or sensors and experiments!

ArduSat – Your Arduino Experiment in Space - [Link]

embedded-lab.com writes:

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]

Build a circuit that displays four channels 0-100C using Pt100 as the temperature sensor. Wichit Sirichote writes:

The RTD or the Pt100 is one of the high accuracy temperature sensor for laboratory. Using the high resolution delta-sigma converter, enables designer to use a simple voltage divider circuit for measuring the resistance of the RTD without the need of any DC amplifications. This instrument shows how to use the LTC2420, 20-bit delta-sigma converter and the LM385 reference voltage for measuring four Pt100 sensors and displays on the text LCD.

4-Channel Pt100 Thermometer - [Link]

diy.viktak.com writes:

The geek inside me has always wanted a fridge that shows the inside temperature for both the freezer and the fridge compartments. However, when we recently replaced our very old fridge we ended up getting a new one without the built in thermometer. So I decided that one of my next projects would have to rectify this problem.

Dual PIC Thermometer - [Link]

z097dsa writes:

This is a project for a Russian IN-13 bargraph Nixie tube to use it as an indoor room thermometer. It is named “NixieTherm” and is also available as a fully complete kit incl. enclosure as shown at www.Nixiekits.eu

The IN-13 is a special construct of a gas discharge Neon display and works similar to the well know Neon bulb in illuminated mains power switches or as Nixie tubes. But this bargraph has a current depending length of the glow. As all other cold discharge tubes also the IN-13 needs a “little bit more” high voltage to work; at least 120VDC. The current through the tube must be limited, normally with a resistor. In the NixieTherm this is done with a high voltage transistor, as we need a variable current from 0….4.5mA.

Analog IN-13 bargraph Nixie tube thermometer - [Link]

Charalampos Andrianakis writes:

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]

circuitvalley.com writes:

This is General purpose Temperature meter for measuring Temperature from -55 ºC to 150 ºC ..It is a very useful bench test equipment for testing and finding out the temperature of various devices with unknown temperature such as room temperature , cpu cabinet, etc. The meter provides very stable readings and has excellent input sensitivity thanks to LM 35 Temperature sensor from National Semiconductor , so it can even measure small temperature change.

The LM35 is three terminal temperature sensor which gives output in the form of analog voltage. LM35 linear to the whole temperature range it generate 10 mV/ºC. this analog voltage is feed to the internal 10 bit analog to digital convertor of the PIC 18F458 which convert it into temperature and then display to the NOKIA 3315/3310 LCD.

Nokia 3315 LCD Based Temperature Meter - [Link]

jumperone.com writes:

Very often in electronics you would need to measure temperature, not just in one spot, but simultaneously in two or more spots. And log that measurements, so that you can plot temperature change over time.
Also, differential temperature measurements could be extremely useful in some cases, especially for thermal design of electronic projects.

So, the other day I bought this UNI-T UT325 dual-channel logging thermometer for a little under $80.

UNI-T UT325 Thermometer Review - [Link]