Solid State Electronics : Basic Solid State Electronic Components

 

1. Diodes:

   • Composed of p-type and n-type materials.
   • Act like a check valve, allowing one-way flow (forward bias) and blocking the reverse flow (reverse bias).
   • Used to manipulate AC currents and as solid-state rectifiers to convert AC to DC currents.
   • Differentiated by current rating: diodes (<1 amp) and rectifiers (>1 amp).

2. Transistors:

   • Can function as amplifiers or switches.
   • Amplifiers: Increase a small input current to a larger output current (e.g., relays in HVAC systems).
   • Composed of three parts: base (gate controller), collector (electrical supply), and emitter (outlet).
   • Work as switches by using a small current to control a larger current.
   • Essential components in microchips and flash drives.

3. Rectifiers:

   • Convert AC to DC currents by allowing current to flow in one direction and blocking the reverse.
   • Full-wave bridge rectifiers use four diodes to produce a DC output from an AC input.
   • Commonly found in HVAC systems to power DC components efficiently.

4. Wheatstone Bridge:

   • Uses resistors to detect small variations in resistance.
   • Compares the resistance of an RTD (high precision resistor) with known resistors to measure temperature changes.

5. Silicon-Controlled Rectifiers (SCRs) or Thyristors:

   • Consist of layered semiconductor materials (PNPN junction).
   • Can block both reverse and forward currents and can be switched on/off to control current flow.
   • Replacing larger transformers in HVAC systems, providing controlled power for refrigeration compressors and fan motors.

6. DIAC (Diode AC Switch):

   • A bidirectional semiconductor switch that can be turned on in both forward and reverse polarities.
   • Often used as switching or controlling devices for TRIACs.

7. TRIAC (Triode AC Switch):

   • Composed of two SCRs with combined gate terminals.
   • Four-layer, three-terminal bidirectional devices that switch high voltages and currents over both parts of an AC waveform.
   • Ideal for power switching applications like motor speed control in AC motors.
   • Used for low to medium power electronic switching applications, with heavier duties left to thyristors.