The **EM14R0A-R20-R032S** is a high-precision rotary optical encoder manufactured by **Bourns**. It is part of the EM14 series, designed for applications requiring high reliability and a long cycle life compared to traditional mechanical encoders. --- ### 1. Part Number Breakdown Understanding the specific configuration of this component: | Code Segment | Meaning | Description | | :--- | :--- | :--- | | **EM14** | Model Series | 14 mm Rotary Optical Encoder | | **R** | Terminal Configuration | Rear Facing PC Pins | | **0** | Housing/Bushing | Standard Plastic Housing | | **A** | Detent Option | No Detents (Smooth Rotation) | | **R20** | Shaft Length | 20 mm Shaft Length | | **R** | Shaft Style | Round Shaft | | **032** | Resolution | 32 Pulses per Revolution (PPR) | | **S** | Switch Option | Includes Push-Momentary Switch | --- ### 2. Technical Specifications This device converts the angular position or motion of a shaft into an analog or digital code. * **Type:** Optical (Non-contacting technology reduces wear) * **Resolution:** 32 Pulses per Revolution (PPR) * **Operating Voltage:** 5.0 VDC ± 0.25 VDC * **Supply Current:** 26 mA maximum * **Output Type:** 2-bit Quadrature (Channel A and B) * **Rotational Life:** Up to 1,000,000 cycles * **Switch Type:** Push-momentary (tactile feedback) --- ### 3. Key Electronic Components & Working Principle The EM14 series operates using an internal optical sensor system: 1. **Infrared (IR) LED:** Acts as the light source. 2. **Code Wheel:** A disc with 32 slits that spins between the LED and the phototransistor. 3. **Phototransistor Array:** Detects the light pulses passing through the code wheel. 4. **Quadrature Output:** By using two offset sensors, the encoder generates two signals (A and B). The phase difference between A and B allows the microcontroller to determine the **direction** of rotation (Clockwise vs. Counter-Clockwise). --- ### 4. Pinout Configuration Typically, the "Rear Facing" (R) pin configuration follows this standard layout: | Pin Number | Function | Description | | :--- | :--- | :--- | | **1** | B Channel | Quadrature Output B | | **2** | VCC | +5V Power Supply | | **3** | GND | Ground | | **4** | A Channel | Quadrature Output A | | **5 & 6** | Switch | Two pins for the momentary push switch | --- ### 5. Common Applications * **Medical Equipment:** High-reliability interfaces for ventilators or imaging machines. * **Audio/Video:** Digital mixing consoles and high-end volume controls. * **Industrial Controls:** Precision parameter adjustment where mechanical wear must be avoided. * **Test & Measurement:** Oscilloscopes and signal generators. ---