How to Use selector switch: Examples, Pinouts, and Specs

A selector switch, manufactured by SA (Part ID: SA), is an electromechanical device designed to allow users to select between multiple circuit paths or functions. It typically features multiple positions, enabling control over various operations in a circuit. Selector switches are widely used in industrial control panels, machinery, and consumer electronics for their reliability and ease of use.

• Industrial control systems for selecting machine modes (e.g., manual, automatic, off).
• Consumer electronics for switching between different operational modes.
• Audio equipment for input/output source selection.
• Test and measurement devices for selecting ranges or functions.
• Home automation systems for controlling lighting or appliances.

• Manufacturer: SA
• Part ID: SA
• Switch Type: Rotary or lever-based selector switch
• Positions: 2 to 12 positions (depending on the model)
• Contact Configuration: Single Pole Single Throw (SPST), Single Pole Double Throw (SPDT), or Double Pole Double Throw (DPDT)
• Voltage Rating: Up to 250V AC/DC (varies by model)
• Current Rating: 5A to 20A (varies by model)
• Mounting Style: Panel mount or PCB mount
• Material: High-durability plastic and metal contacts
• Operating Temperature: -20°C to +70°C

The pin configuration of a selector switch depends on its contact configuration. Below is an example for a 3-position SPDT selector switch:

For a DPDT selector switch, the pin configuration is as follows:

1. Determine the Configuration: Identify the number of positions and poles required for your application. For example, a 3-position SPDT switch can toggle between two outputs or functions.
2. Connect the Terminals:
   • Connect the common terminal (COM) to the input signal or power source.
   • Connect the NO terminals to the desired output paths or devices.
3. Mount the Switch: Secure the selector switch to a panel or PCB using the appropriate mounting hardware. Ensure the switch is firmly in place to prevent accidental movement.
4. Test the Circuit: After wiring, test the circuit to ensure the selector switch operates as intended.

• Voltage and Current Ratings: Ensure the selector switch's voltage and current ratings match or exceed the requirements of your circuit.
• Debouncing: If the selector switch is used in a digital circuit, consider implementing software or hardware debouncing to avoid false triggering.
• Position Marking: Clearly label the positions of the selector switch to avoid confusion during operation.
• Environmental Conditions: Use selector switches rated for the operating environment, especially in high-temperature or high-humidity conditions.

Below is an example of using a 3-position SPDT selector switch with an Arduino UNO to toggle between three LEDs.

// Define pin connections for the selector switch and LEDs
const int switchPin1 = 2; // NO terminal for Position 1
const int switchPin2 = 3; // NO terminal for Position 2
const int led1 = 8;       // LED for Position 1
const int led2 = 9;       // LED for Position 2
const int led3 = 10;      // LED for Position 3 (default)

// Setup function to initialize pins
void setup() {
  pinMode(switchPin1, INPUT_PULLUP); // Enable internal pull-up resistor
  pinMode(switchPin2, INPUT_PULLUP); // Enable internal pull-up resistor
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
}

// Main loop to read switch state and control LEDs
void loop() {
  // Read the state of the selector switch
  bool position1 = digitalRead(switchPin1) == LOW; // Active LOW
  bool position2 = digitalRead(switchPin2) == LOW; // Active LOW

  // Control LEDs based on switch position
  if (position1) {
    digitalWrite(led1, HIGH); // Turn on LED1
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
  } else if (position2) {
    digitalWrite(led1, LOW);
    digitalWrite(led2, HIGH); // Turn on LED2
    digitalWrite(led3, LOW);
  } else {
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, HIGH); // Default to LED3
  }
}

1. Switch Not Functioning:

   • Cause: Loose or incorrect wiring.
   • Solution: Double-check the wiring and ensure all connections are secure.

2. Intermittent Operation:

   • Cause: Contact wear or dirt accumulation.
   • Solution: Clean the contacts with a contact cleaner or replace the switch if necessary.

3. Incorrect Position Detection:

   • Cause: Debouncing issues in digital circuits.
   • Solution: Implement software debouncing in your microcontroller code.

4. Overheating:

   • Cause: Exceeding the switch's current or voltage rating.
   • Solution: Use a switch with appropriate ratings for your application.

• Q: Can I use a selector switch for AC circuits?
  A: Yes, as long as the switch's voltage and current ratings are suitable for the AC circuit.

• Q: How do I know which position the switch is in?
  A: Most selector switches have a physical indicator or detent mechanism to show the current position.

• Q: Can I use a selector switch with more than two poles?
  A: Yes, multi-pole selector switches are available for applications requiring multiple independent circuits.

• Q: Is the selector switch waterproof?
  A: Some models are designed to be waterproof or weather-resistant. Check the product specifications for details.