Chapter 7

1. MOSFETs are voltage-controlled components, while BJTs are current-controlled components.
2. You do not have a pull-down resistor on the MOSFET's gate leg, so it's left floating. The MOSFET discharges slowly and this is reflected as the motor is spinning down. Using a pull-down resistor ensures the MOSFET discharges promptly and becomes off.
3. (a) Make sure the G, S, and D legs are connected correctly because different package styles (for example, T092 versus TP220) have their legs ordered differently.
   (b) You also want to make sure that the MOSFET is logic-level compatible so that it can be controlled using a 3.3-volt voltage source.
   (c) Ensure that the voltage divider created between the pull-down resistor and the current limiting resistor allows >~3 volts into the MOSFET's gate leg.
4. Optocouplers and relays electrically isolate the input and output sides of a circuit. Transistors are in-circuit, and while they allow a low-current device to control a...