Resistors

Resistors are fundamental passive components in electronic circuits. They limit current, divide voltage, set time constants, and serve as pull-up/pull-down, termination, and current-sensing elements. This category covers fixed resistors, variable types, and high-power models.

Fixed Resistor Types

• Carbon film: Low cost for general-purpose applications.
• Metal film: High precision, low noise, and excellent temperature stability; ideal for measurement circuits.
• Metal oxide: Reliable in high-temperature environments.
• Wirewound: High power rating, available with low inductance options; used in current sensing and power circuits.
• SMD (surface mount): Standard for compact PCB designs, available in packages from 0402 to 2512.

Variable Resistors & Selection Criteria

Variable resistors (potentiometers) allow manual adjustment of voltage division ratios or resistance values. Trimpots are soldered onto PCBs for one-time calibration. For high-current applications, aluminum-clad power resistors or wirewound types are preferred.

Key parameters for resistor selection: resistance value (ohms), power rating (watts), tolerance (%), temperature coefficient (ppm/°C), and maximum operating voltage. In precision circuits, tolerance and temperature stability are critical; in switching circuits, resistor noise and inductive effects must be considered. Choosing the right type directly impacts circuit performance and reliability.