The **LTHZ-123-R** is a specific electronic component typically categorized as a **Photointerrupter** (also known as an Optical Slot Switch). These devices are used to detect the presence or absence of an object by breaking an infrared light beam. --- ## 1. Technical Specifications The device consists of an Infrared Emitting Diode (IRED) and a Phototransistor facing each other across a narrow gap. | Parameter | Description | Typical Value | | :--- | :--- | :--- | | **Input Type** | Infrared LED | 1.2V - 1.5V Forward Voltage | | **Output Type** | Phototransistor | NPN | | **Slot Width** | Physical gap for object sensing | ~3.0 mm | | **Mounting Type** | Through-Hole | PCB Mount | | **Response Time** | Switching speed | ~10μs to 20μs | | **Operating Temp** | Thermal range | -25°C to +85°C | --- ## 2. Pinout Configuration The LTHZ-123-R usually features four pins, split into two sides: 1. **Anode (+):** Positive lead for the internal Infrared LED. 2. **Cathode (-):** Ground/Negative lead for the LED. 3. **Collector (C):** The "Output" pin of the phototransistor. 4. **Emitter (E):** The ground lead for the phototransistor. --- ## 3. Working Principle The device operates on the principle of **Optical Interruption**: * **State 1 (Idle):** The internal LED emits infrared light. The phototransistor on the opposite side receives this light and stays "ON" (conducting). * **State 2 (Interrupted):** An opaque object (like a plastic gear or encoder disk) passes through the slot. The light beam is blocked. The phototransistor turns "OFF" (non-conducting). * **Signal Output:** This transition from ON to OFF creates a pulse that a microcontroller (like an Arduino or PLC) can count or use to trigger an event. --- ## 4. Common Applications Due to its reliability and small size, the LTHZ-123-R is used in: * **Printers/Scanners:** Detecting the "Home" position of the print head or paper presence. * **Speed Measurement:** Working with a slotted wheel to measure Motor RPM (Tachometer). * **End-Stops:** Preventing mechanical arms from moving beyond their physical limits. * **Counters:** Counting items on a small-scale conveyor belt. ---