The **FRS-04-R** typically refers to a specific model of a **Miniature Liquid Level Float Switch**. These components are widely used in automation, appliance manufacturing, and industrial tank monitoring to detect the presence or absence of liquid. Below is a detailed breakdown of its electronic and mechanical specifications. --- ### 1. Technical Specifications The FRS-04-R is a reed-switch-based sensor. Its primary function is to act as a dry contact switch triggered by a magnetic field. | Feature | Specification (Typical) | | :--- | :--- | | **Switching Type** | Reed Switch | | **Contact Form** | Form A (Normally Open - N/O) | | **Max Contact Rating** | 10W / 50W (depending on variant) | | **Max Switching Voltage** | 100V DC / 250V AC | | **Max Switching Current** | 0.5 A | | **Material** | PP (Polypropylene) or Stainless Steel | | **Mounting** | Vertical (Top or Bottom) | --- ### 2. Internal Components & Operation The "Electronic" side of this part is relatively simple but highly reliable due to its passive nature. * **The Reed Switch:** Inside the central stem is a hermetically sealed glass tube containing two ferromagnetic reeds. * **The Magnetic Float:** A donut-shaped float contains a permanent magnet. As the liquid level rises or falls, the float moves along the stem. * **Activation:** When the magnet in the float aligns with the reed switch inside the stem, the magnetic field pulls the reeds together, closing the circuit. ### 3. Wiring and Logic Configuration One of the most versatile aspects of the FRS-04-R is its reversible logic. #### Reversing the Logic (N/O to N/C) By default, these switches are often **Normally Open (N/O)**, meaning the circuit closes when the float rises. 1. Remove the "E-clip" (retaining ring) at the bottom of the stem. 2. Take the float off and flip it 180 degrees. 3. Reinstall the float and clip. 4. The switch will now function as **Normally Closed (N/C)**. #### Application Circuit Example Because reed switches have low current ratings, they should not drive motors or pumps directly. They are typically used to trigger a **Relay** or an **MCU input**. ```cpp // Example: Connecting FRS-04-R to an Arduino int sensorPin = 2; // Connected to FRS-04-R int ledPin = 13; // Indicator void setup() { pinMode(sensorPin, INPUT_PULLUP); // Use internal resistor pinMode(ledPin, OUTPUT); } void loop() { int levelState = digitalRead(sensorPin); if (levelState == LOW) { digitalWrite(ledPin, HIGH); // Tank Full } else { digitalWrite(ledPin, LOW); // Tank Empty } } ``` --- ### 4. Precautions for Use * **Inductive Loads:** If using the FRS-04-R to switch a relay coil, always use a **Flyback Diode** (e.g., 1N4007) to prevent voltage spikes from welding the reed contacts together. * **Chemical Compatibility:** Ensure the Polypropylene (PP) body is compatible with the liquid being measured (e.g., water, oil, or mild acids).