## Overview of the HRS-1D-R Relay The **HRS-1D-R** is a popular miniature signal relay manufactured by HKE (Zhejiang HKE Relay Co., Ltd). It is widely used in telecommunications, security systems, and household appliances due to its compact size and high reliability. --- ### Technical Specifications The following table outlines the primary electrical and mechanical characteristics of the HRS-1D-R series: | Parameter | Specification | | :--- | :--- | | **Contact Form** | 1 Form C (SPDT - Single Pole Double Throw) | | **Max Switching Current** | 3A | | **Max Switching Voltage** | 120VAC / 24VDC | | **Coil Nominal Voltage** | 3V, 5V, 6V, 9V, 12V, 24V DC (Model dependent) | | **Coil Power Consumption** | Approx. 200mW to 360mW | | **Contact Resistance** | Max 100mΩ (initial) | | **Dielectric Strength** | 500VAC (between open contacts) / 1000VAC (between coil & contacts) | | **Operating Temperature** | -30°C to +70°C | --- ### Internal Electronic Construction The HRS-1D-R consists of several key electronic and mechanical components: 1. **Electromagnetic Coil:** A copper wire winding that generates a magnetic field when DC current flows through it. The "R" in the part number often signifies a high-sensitivity version with lower power consumption. 2. **Armature:** A moving metal piece attracted by the coil's magnetic field. 3. **Spring Mechanism:** Ensures the contacts return to their default (Normally Closed) position once power is removed. 4. **Contacts (Ag Alloy):** Silver alloy contacts (often Silver-Nickel or Silver-Cadmium Oxide) provide low resistance and prevent oxidation over time. 5. **Sealing:** The unit is typically plastic-sealed (wash-tight), allowing it to be used in environments where soldering flux or cleaning agents are present. --- ### Pin Configuration (Typical Layout) The relay features a standard **6-pin or 5-pin DIP** (Dual In-line Package) footprint: * **Coil Pins (2 pins):** Connected to the driving circuit. * **Common (COM):** The central terminal that switches between the two outputs. * **Normally Closed (NC):** Connected to COM when the coil is **off**. * **Normally Open (NO):** Connected to COM when the coil is **on**. --- ### Application Circuit Tips When integrating the HRS-1D-R into an electronic design, consider the following: * **Flyback Diode:** Always place a diode (e.g., 1N4148) in parallel with the coil (anode to ground, cathode to VCC) to protect your driving transistor from inductive voltage spikes. * **Driving Transistor:** Since the coil draws 20mA–70mA (depending on voltage), a small NPN transistor (like the 2N2222) or a MOSFET is required to drive it from a microcontroller. ---