Question 1

What do the third-digit values 8 and 9 mean in capacitor codes?

Accepted Answer

Unlike digits 0–7 which represent multipliers of 10⁰ to 10⁷, digit 8 means ×0.01 and digit 9 means ×0.1. For example, code '158' = 15 × 0.01 = 0.15 pF, and code '159' = 15 × 0.1 = 1.5 pF. These are used for very small capacitance values in RF and high-frequency circuits.

Question 2

How can I tell a capacitor code from a resistor code on an unmarked SMD component?

Accepted Answer

SMD capacitors (MLCCs) are typically unmarked or use the 3-digit pF code system. SMD resistors use a 3 or 4-digit ohm code (e.g., '103' = 10 kΩ). Physically, SMD capacitors tend to be squarer with no markings, while resistors are rectangular with printed codes. When in doubt, measure with a multimeter's capacitance mode.