How to Calculate Resistor Value?

A complex resistance circuit is made up of a large number of resistors connected in series and in parallel.

It will form a complex resistance network. We need to think about calculating the sum of the circuit resistance, current, and voltage of these resistance combinations.

A resistor combination or hybrid resistor circuit is a resistor circuit that combines series and parallel resistor networks. The calculation method of the circuit in series or parallel is the same as the method of equivalent resistance. The resistors connected in series carry exactly the same current, and the resistors connected in parallel have exactly the same voltage.

Step 1

The method of calculating the total current (IT) obtained by the 12v power supply in the circuit is as follows：

Step 2

Through careful observation, we can see two resistors. R 2 and R 3 are combined. The addition of R 2 and R 3 produces the same resistance. The combined resistance of this combination is: R 2 + R 3 =8Ω+4Ω=12Ω. We can replace R 2 and R 3 with 12Ω.

Step 3

There is a resistor R A and a resistor R 4 in the “PARALLEL” of the circuit. For the resistors in the parallel equation, we can use the following two parallel resistor formulas to reduce the parallel combination to a single equivalent resistance value R (combination).