The **A10203-RSC-QK** is a high-precision, subminiature rotary switch manufactured by **C&K (now part of Littelfuse)**. It is part of the A Series, which is widely recognized for its versatility in industrial and consumer electronics. ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Circuitry** | SPDT (Single Pole, Double Throw) | | **Number of Positions** | 2 Positions | | **Contact Rating** | 2.5A @ 125V AC; 350mA @ 125V DC | | **Indexing** | 30° or 45° (Standard 30°) | | **Mounting Type** | Through-hole, PC Mount | | **Termination Style** | PC Pin | | **Actuator Style** | Flatted (with Slot) | --- ### 2. Detailed Component Breakdown #### A. Contact Mechanism The "RSC" in the part number indicates the contact material and plating. * **Material:** Typically silver-plated copper alloy. * **Performance:** Designed for "Shorting" (Make-before-break) or "Non-shorting" (Break-before-make) depending on the specific sub-configuration, though the standard A102 is usually non-shorting. #### B. Housing and Build * **Bushing:** Zinc die-cast with nickel plating for durability and grounding. * **Housing:** Glass-filled 6/6 nylon (UL 94V-0 rated), providing high thermal resistance during soldering and excellent electrical insulation. #### C. Environmental Limits * **Operating Temperature:** -30°C to +85°C. * **Dielectric Strength:** 1,000 Vrms at sea level. * **Insulation Resistance:** $10^9$ ohms minimum. --- ### 3. Part Number Nomenclature (Decoding) To understand the electronic properties, we can break down the identifier: | Segment | Meaning | | :--- | :--- | | **A102** | **Series & Function:** 1-Pole, 2-Position rotary switch. | | **03** | **Actuator:** 0.375" (9.53mm) flatted actuator length. | | **RSC** | **Termination/Contact:** PC Thru-hole pins with silver contacts. | | **Q** | **Contact Material:** Silver (Power rating). | | **K** | **Sealing/Options:** Usually denotes a specific hardware or RoHS compliance packaging. | --- ### 4. Common Applications * **Test & Measurement:** Oscilloscopes and multimeters for mode selection. * **Industrial Controls:** Parameter adjustments on DIN rail equipment. * **Audio Gear:** Input switching or gain stage selection in pre-amps. * **Medical Equipment:** Device setting toggles where a physical tactile click is required for safety.