LED Thermometer

We receive informations about temperature or use thermometers almost every day. But have you ever wondered how temperature is actually measured?

After completing this great starter kit user will get nice interactive LED thermometer. With this kit you will learn one principle how temperature can be measured in simple but precise way. It is a very good design using low cost industry standard parts.

Thermometer Specifications:

Temperature measurement range: 0-40 degree Celsius
Indication: 20 LEDs (2 degree Celsius per LED)
Power Supply: 5V - 9V (Recomended 9V battery or 5V from PC USB port)
Supply Connectors: 9V Battery snap and female USB port (male to male USB cable included in kit)
Switches: Tactile switch for momentary temperature indication and Slide Switch for permanent indication
Dimensions: 2.7cm x 17cm (1.0630 inch x 6.6929 inch)

This thermometer indicates temperature with 20 blue 5mm LEDs and measures temperature in ranges from 0 to 40 degrees Celsius, each LED corresponds to 2 degree Celsius. LEDs will turn ON in the same way as Mercury rises in standard thermometer.

Power Supply for LED thermometer can be standard 9V battery, but there is also USB connector on the PCB so this device can be supplied from PC USB port (do not connect 9V battery and USB power supply at the same time!)

Kit includes 9V battery snap and 6 feet USB male to male cable.

Each LED with large viewing angle is driven with 12.5 mA current which ensures their brightness. Tactile switch is pressed to turn ON device to indicate temperature and when tactile switch is released device will turn OFF. Also there is sliding switch which will keep thermometer permanently turned ON or OFF.

Check out this link if you want to see 3D Model of assembled LED Thermometer:


Click on 3D view marked with red.


PampangaAudio (Nov 28, 2015)
Maybe use Blue LED from 0 to 14 degrees C to indicate cool temp, Green LED from 16 to 24 degrees C & Red LED from 26 to 40 degrees C for warm temp though temperature is really subjective as it depends on the location.