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'Celsius' electronics kit

'Celsius' is an electronics kit aimed at young people. Correctly soldering the components onto the included printed circuit board (PCB) creates a badge that measures the temperature, and also keeps track of the minimum and maximum temperatures. As a bonus, the badge lets you play a small memory game.

English text Er is ook een pagina in het Nederlands aanwezig.

Celsius voorzijde Celcius achterzijde
The front and back of a ready built Celsius.


You can send your questions about the Celsius project to ivo [atsign] digiterraan.nl.

The engineers

Ivo PA1IVO and Leo PA0LEZ.

Thanks to

Building instructions

The building instructions can be found in a colour PDF file. When printing the instructions, use a colour printer in order to see the red lines in the pictures. The instructions are only available in Dutch, but the building instructions will be useful for everyone due to the graphical presentation.


In the manual you can find all the information you need to know to operate the Celsius, however in Dutch only. It is a PDF file in A4-format, containing two A5 columns of text. By double-side printing the A4 and cutting it exactly into two equal parts, you get two manuals in A5 format.

Temperature correction

Extra calibration on PCB According to the specifications the TMP36 temperature sensor can vary up to 2 degrees. If the temperature displayed on the Celsius indeed deviates, this can be corrected on the PCB of the Celsius.

By means of 4 different soldering bridges, the temperature on the display can be shown 3.5 higher or lower at maximum, in steps of 0.5 degrees. If a soldering bridge is present, it is selected. At the start up of the micro controller the state of the soldering bridges are read in.



schematic sound kit
Schematic of the Celsius electrical circuit.

Electronic parts

Part & reference Name / value Manufacturer part number Supplier & order code
8 Resistors 470 Ω VISHAY MRS25000C4700FCT00 Farnell 9468463
Capacitors C1,C2,C3 100 nF (pitch 5 mm) VISHAY K104K15X7RF53H5 Mouser 594-K104K15X7RF53H5
2 Led displays 1.3cm Segment display Orange CA GNS-5213BUY LEDs-buy A3-04-01-OR
6 Switches Tactile Switch off-(on) ALPS SKHHARA010 Farnell 1656425
TMP36 Temperature Sensor TMP36GT9Z TME TMP36GT9Z
IC socket 28 pins (2 x 14) 7.62mm spacing ASSMANN WSW AR 28 HZL/7-TT RS 674-2498
Microcontroller ATmega48PA-PU Microchip ATmega48PA-PU Reichelt ATMEGA48PA-PU
Battery holder Battery holder 2 x AAA Keystone Electronics 2468 Mouser 534-2468
Batteries 2 x 1,5 Volt AAA - Your local shop

Sound Kit parts
Electronic parts Celsius.

PCB layout

The PCB layout is available as: The PCBs are manufactured at Safe-PCB.


The micro controller (ATmega48PA, device signature 0x1E920A) firmware is available as .hex file. The fuse bits settings are: 0xFF, 0xD6, 0x62 (extended, high, low).


Celsius Snow Negative Temperature
Celsius at minus four degrees in the snow.

Celsius design prototype

Celsius design prototype.

2019-2023 by Ivo Klinkert, PA1IVO - Contact