91.305 Assignment 3B: Transistor Circuits

91.305 Assignment 3B: Transistor Circuits

1. In the circuit below, assume that a logic high (3.6v in this case) is applied to the input. Using blue pen or pencil (NOT black pen), draw on the diagram the path of current flow through the transistor. Indicate with arrows the direction of current as it flows from (+) to (-). Use a thicker line to indicate more current.
   
2. In the case above, is the output value a logic high or a logic low? (Circle the correct answer.)
3. In the circuit below, assume that R1 is 1k and R2 is 500 ohms. How much current flows through R2 when a logic high (3.6v) is applied to the input? Make sure to involve the 0.6v base-emitter voltage drop in your calculation.
   
   
   
   
   
   
   
   
   
   Use the area above for work and your answer.
   
4. In the circuit below, assume that a logic high (3.6v in this case) is applied to the input.
   • Draw on the diagram the path of current flow through the transistors.
   • Indicate with arrows the direction of current as it flows from (+) to (-).
   • Use a thicker line to indicate more current.
   • Circle transistor(s) that are turned on.
   
   
5. In the case above, is the OUT2 output value a logic high or a logic low? (Circle the correct answer.)
   
   
   
   
   
6. With the same circuit, assume that a logic low (0v) is applied to the input.
   • Draw on the diagram the path of current flow through the transistors.
   • Indicate with arrows the direction of current as it flows from (+) to (-).
   • Use a thicker line to indicate more current.
   • Circle transistor(s) that are turned on.
   
   
7. In the case above, is the OUT2 output value a logic high or a logic low? (Circle the correct answer.)
   
   
   
   
   
   
   
   
   
   
8. The circuit below shows a TTL implementation of a NAND gate.Assume that both the inputs are logic high. Circle the transistors that are turned on. Important: when a transistor is off, current is allowed to flow from the base through the collector (backwards to how it would flow if the transistor were turned on).
   
   
9. Same circuit; now assume that both the inputs are logic low. Circle the transistors that are turned on. As before, when a transistor is off, current is allowed to flow from the base through the collector (backwards to how it would flow if the transistor were turned on).