I had for a very long time the project of creating an automated aquarium project with an Arduino UNO.
I started my work towards that goal yesterday by hooking up a waterproof temperature sensor (https://www.gotronic.fr/art-sonde-etanche-ds18b20-19339.htm) to the Arduino and a simple LCD screen (https://www.gotronic.fr/art-afficheur-lcd-lmb0820-19017.htm) that will simply display the temperature of the water in the tank.
I then hacked a 50W aquarium heater (removing the thermostat) and connected it to a relay controlled by the Arduino, and wrote some basic code to turn the heater on/off based on a certain range of temperatures.
Everything works flawlessly up to now, no obvious problem, the relay, the temperature sensor and the lcd screen all work as expected.
And then I noticed that something was wrong...
I touched the Atmega328 chip on the UNO and noticed that it was quite hot, it made me a worried. When I then touched the linear voltage regulator, it was burning hot!
Something was obviously wrong... I thought about obvious possible problems, but since I'm still a beginner in the field I wanted to have some feedback from pros!
I instantly thought about one of the components from my project driving excessive current ? But thinking about the connected components this seemed quite unlikely (they do not require so much current) ?
I thought also about the power supply being at an excessive voltage (I'm using a 24V, 1A power supply) that I hooked to a buck converter lowering the voltage to ~8V and plugged the output of the Buck to the Vin pin of the Arduino, which if I'm not mistaken accepts between 7-12V DC ? So it shouldn't be the problem no?
The Arduino is damaged and behaves in a weird way ? I noticed yesterday that even though the project prototype was working fine when the relay was switched on/off sometimes something was going wrong with the screen displaying some random weird text and freezes... I have genuinely no idea what this means?
If someone could give me some hints about this?