It appears you are referring to the **28-R** designation, which is most commonly associated with **Surface Mount Device (SMD) resistors** or specific **potentiometer/trimmer** series. Below is an explanation of the electronic components categorized under the "28-R" label, focusing on the most common applications. --- ## 1. 28-R as an SMD Resistor Code In electronics manufacturing, "28R" is frequently a marking used to denote the resistance value of a component. ### Value Decoding | Marking | Meaning | Resistance Value | | :--- | :--- | :--- | | **28R** | Direct Ohmic Value | 28 Ohms (Ω) | | **28R0** | 4-digit precision | 28.0 Ohms (Ω) | | **R28** | Fractional Ohmic Value | 0.28 Ohms (Ω) | ### Technical Specifications * **Type:** Fixed Resistor (usually Thick Film or Thin Film). * **Package Sizes:** Can come in standard EIA sizes like 0603, 0805, or 1206. * **Tolerance:** Typically ranges from ±1% to ±5%. --- ## 2. The 28-R Potentiometer Series Many manufacturers (such as Bourns or Vishay) use numeric prefixes for their potentiometer or "trimmer" lines. A "28-R" component in this context usually refers to a **Panel Control** or a **Variable Resistor**. ### Features of the 28-R Control Series * **Function:** Used for manual adjustments of voltage or current in a circuit. * **Mounting:** Often designed for panel mounting with a threaded bushing. * **Rotation:** Usually single-turn (approx. 270° to 300° of travel). * **Terminal Types:** * **Solder Lugs:** For manual wiring. * **PC Pins:** For direct mounting onto a Printed Circuit Board. --- ## 3. Identification Table If you are looking at a specific physical part, use this table to identify it: | Physical Appearance | Likely Component | Function | | :--- | :--- | :--- | | Small black rectangle with "28R" printed in white | **SMD Resistor** | Limits current or divides voltage. | | Metal or plastic cylinder with a rotating shaft | **Potentiometer** | User-adjustable resistance (volume, light dimming). | | Small blue/white cube with a screw head | **Trimmer Pot** | Fine-tuning internal circuit parameters. | --- ## Summary of Usage * **Power Supplies:** Low-value 28-R resistors (like 0.28Ω) are often used for **current sensing**. * **Audio Equipment:** 28-series potentiometers are found in vintage and modern audio mixers for gain control. * **LED Circuits:** 28Ω resistors are used to limit current for high-brightness LEDs depending on the input voltage.