Power selection of current limiting resistor in voltage stabilizing circuit of voltage stabilizing tube Ask a friend who knows, I see a circuit board, 12VDC step-down to 5V power supply to a single-chip microcomputer, using 1n4733, but the first current limiting resistor is 330 ohm 2W, the power of this resistor I feel too large, my calculation is 7 * 7 / 330 = 0.15w or so, know the friends say your views,

Power selection of current limiting resistor in voltage stabilizing circuit of voltage stabilizing tube Ask a friend who knows, I see a circuit board, 12VDC step-down to 5V power supply to a single-chip microcomputer, using 1n4733, but the first current limiting resistor is 330 ohm 2W, the power of this resistor I feel too large, my calculation is 7 * 7 / 330 = 0.15w or so, know the friends say your views,

If 330 Ω resistor is used, the maximum current provided by the circuit is 20mA, which is obviously not enough
It is reasonable to use a resistance of 2W for 1.5W

The function of sliding rheostat in current and voltage resistance experiment

Protect the circuit, change the size of the resistance, and then change the size of the voltage at both ends of the appliance