2024-09-15, 03:23 PM
You can take the voltage (in this case 5v or 3v3) and use the formula: V^2/R to determine wattage.
Generally these resistors see less than the full 5 volts, but you can see a 100 ohm resistor at 5 volts dissipates 1/4th watt. I then try to at least double this, so the 100 ohm resistor might be 1/2 watt, but it would only see this if the output of the regulator is shorted.
So basically every resistor at be 1/8th or 1/10th watt, except the current sensor or arduino power. My newer designs dont use the arduino power resistor but instead regulate current to limit it in case of a short.
Generally these resistors see less than the full 5 volts, but you can see a 100 ohm resistor at 5 volts dissipates 1/4th watt. I then try to at least double this, so the 100 ohm resistor might be 1/2 watt, but it would only see this if the output of the regulator is shorted.
So basically every resistor at be 1/8th or 1/10th watt, except the current sensor or arduino power. My newer designs dont use the arduino power resistor but instead regulate current to limit it in case of a short.