Review on 📊 HiLetgo 5pcs Voltage Detection Module: DC 0~25V Voltage Sensor for Arduino - A Comprehensive Review by Mike Johnston

look from above. The floor is just a ground plane. The top has pin and screw heads and 2 resistors. 30k ohms and 7.5k ohms. Google "Voltage Divider Calculator". However, it lacks a shunt regulator (such as a 25V zener diode) so it is unsafe for unknown voltage sources or spikes. It is also rated for 5V. I mean if you need it because it's convenient for the project, I get it. Anyway, 10-bit resolution = 1024 steps = each step at 5V = 0.025 and each step. Did another comment mention something about how to use this to define a 3 by 3 microcontroller? do not do that. With an input voltage of 25 V, this divider outputs 5 V with the chosen resistor values. If you wanted 3 by 3 you would be closer to 31kΩ and 4.7kΩ and your max input would be slightly higher. 25,066, otherwise 3 times 3, if you don't damage anything, 10-bit resolution at most at 16.5 volts.