First, 24V step-down to 12V, - how much resistance in series is determined by the load current.
Second, the load is a small fan of 12V 0.06A, -- fan working resistance (impedance) : 12\/0.06=200 euros
Third, the theoretical calculation value: the need for a series of 200 ohm resistance!! In practice, 150 euros is more reasonable.
Note: Are you sure the current of the fan is 0.06A??
Dc 24v to 12v resistor is used in series voltage division method for voltage division, that is to say, the load and the series resistance each voltage division 12V. Therefore, this depends on the load resistance value (pure resistance load) or the rated current of the load.
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for example
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1, the resistance value of the load is 6 ohms (pure resistive load), then the resistance of 6 ohms needs to be connected in series.
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2, the resistance value of the load is 10 ohms (pure resistive load), it is necessary to series 10 ohms of resistance.
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3. The rated current of the load is 1A, and a resistance of 12 ohms in series is required.
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4, the rated current of the load is 2A, then a series of 6 ohms of resistance is required.
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Extended information:
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The law of series circuit:
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1, the current flowing through each resistor is equal, because each section of the same branch in the direct current circuit has the same current strength.
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2, the total voltage (series circuit = the voltage at both ends) is equal to the sum of the partial voltage (the voltage at both ends of each resistor), that is, U=U1 U2...... Un. This can be derived directly from the definition of voltage.
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3, the total resistance is equal to the sum of the resistance. Applying Ohm's law to each resistor separately yields U1=IR1,U2=IR2,... Un=IRn and U=U1 U2...... Un and note that the current across each resistor is equal, giving U=I(R1 R2 Rn). This formula states that if a resistance value R=R1 R2... The resistor element of Rn replaces the original series circuit of n resistors, and the current of this element will be the same as that of the original series circuit. Therefore, the resistance R is called the equivalent resistance (or total resistance) of the original series resistance. Therefore, the total resistance is equal to the sum of the component resistance.
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4, the voltage of each resistor is proportional to its resistance value, because Ui=IRi.
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5, the power of each resistor is proportional to its resistance value, because Pi=I2Ri.
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6, the parallel circuit current bifurcation.