7.8. BJT as a Switch

Try these first

1. 1.

   What indicates a BJT is in cut-off region?

   Hint

   Think about the switch being off.

2. 2.

   What is the saturation region in a BJT?

   Hint

   It’s like a switch being closed.

3. 3.

   What state does a BJT represent when in the cut-off region?

   • ON
   • OFF
   • ACTIVE

   Hint

   Relate this to a common household switch.

4. 4.

   A BJT in saturation allows maximum current flow. True or False?

   • True
   • False

   Hint

   Think of a closed circuit.

5. 5.

   Design a circuit that uses a BJT as a switch to control a light bulb, specifying resistances and the power supply needed.

   Hint

   Start with Ohm's law and current gain formula.

6. 6.

   Evaluate how the temperature in a circuit can alter the performance of a BJT used as a switch.

   Hint

   Consider how heat influences conductivity and resistance.