A3.4.8 Output devices and signal conversion Notes

Understanding Output Devices

1. Output devices are components that convert processed signals into a form that can be perceived or used by humans or other systems.
2. They are the final stage in an electronic system, translating digital or analog signals into tangible actions or displays.

Types of Output Devices

Visual Displays

1. LEDs: Emit light when an electric current passes through.
2. LCDs: Use liquid crystals to modulate light and display images.
3. OLEDs: Organic compounds emit light, offering high contrast and flexibility.
4. Plotters: Use pens or cutting heads to draw or cut precise designs from digital data, producing large-scale or highly detailed outputs.

Auditory Outputs

1. Speakers: Convert electrical signals into sound waves.
2. Buzzers: Produce sound through vibration, often used for alerts.
3. Headphones: Deliver sound directly to the user’s ears by converting electrical signals into audio privately.

Data Outputs

1. Printers: Convert digital data into physical documents.
2. Network Interfaces: Transmit data to other devices or systems.

Mechanical Outputs

1. Motors: Convert electrical energy into mechanical motion.
2. Actuators: Move or control mechanisms, often used in robotics.
3. Relays – electromechanical switches that trigger mechanical or electrical actions

Tactile Outputs

1. Haptic Devices – vibration motors or actuators providing feedback (e.g. phones, gaming controllers)
2. Braille Display – generates raised dots to be felt with fingers

Signal Conversion

1. Analog-to-Digital Conversion (ADC)
   1. Purpose: Converts continuous analog signals into discrete digital data.
   2. Process:
      1. Sampling: Captures the signal at regular intervals.
      2. Quantisation: Assigns a numerical value to each sample.
      3. Encoding: Converts these values into binary code.
2. Digital-to-Analog Conversion (DAC)
   1. Purpose: Transforms digital data back into continuous analog signals.
   2. Process:
      1. Decoding: Converts binary data into numerical values.
      2. Reconstruction: Generates a continuous signal from these values.

Signal Conditioning in Analog Systems

1. Amplification
   1. Purpose: Increases signal strength without altering its content.
   2. Example: Boosting a weak microphone signal for processing.
2. Filtering
   1. Purpose: Removes unwanted noise or frequencies.
   2. Example: A low-pass filter allows only low-frequency signals to pass through.
3. Modulation
   1. Purpose: Alters a signal to carry information or fit a specific medium.
   2. Example: Modulating a radio signal for transmission.