# Diode Digital Thermometer Circuit

This digital thermometer circuit diagram uses a common 1N4148 diode as the temperature sensor. The temperature coefficient of the diode, -2 mV/°C is exploited for this application to create an accurate electronic thermometer.
To display the measured temperature, a digital multimeter is used and so we can measure temperature values from -9.99°C up to +99.9°C.

Calibration of the digital thermometer

To set the minimum level (0°C), place the diode in a glass of water filled with crushed ice (check the temperature first with a normal thermometer) wait until the thermometer shows zero degrees centigrade. Set P1 so that the digital voltmeter will display 000 when the diode senses zero degree centigade.
To set the maximum level (100°C), place the diode sensor into a boiling water and adjust P2 so that the digital meter exactly displays 99.9.

## Schematic of the digital electronic thermometer circuit

For more digital thermometers check related articles.

• mthembenimkhizeyahoo-com

may you please send me the circuit diagram of electronic thermometer using 741 op amp on the following email :mthembenimkhize@yahoo.com

• Rev

Please send me more details of the experiment
And also the components used in it
What is a1,a2,a3
Thank you

• josephparayaruthottam

how to measure temperature.we get the output of multi meter as voltage.how to measure temperature

• rhon

i tried this circuit but I have a problem with the calibration. P1 does not seem to have an effect. why is that? I cant do the calibration. pls help

• Greg9205

Hi I have had the same problem, do you know what the fix is? or why there is a problem with this stage?

Thanks Greg

• GHAYAS

how does it work? when i heat the diode temperature is decrease….. whats the reason behind it plzz tell me

• ss

can u plz send me a complete circuit of digital thermometer. i really need it for my mini project…..

• AYODEJI

Please Waheed & any other person that can help me to pls send me the full diagram of the circuit and any other hint that can help me in achieving success in building the thermometer myself, I have interest in the project.

• nazirah

can plz send me a complete circuit of digital thermometer.. i really need it for my mini project..

• sulaiman

pls, Waheed or anybody that have full circuit diagram of diode digital thermometer and project report should pls send it to me via my mail:abey124@gmail.com. this is my project thank you all

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