Cooling Fan Control Circuit Concepts

The video tutorial explains how to use thermal switches to create simple circuits for temperature indication and cooling fan control. It covers the working principle of thermal switches, the design of a basic temperature indicator circuit using an NPN transistor and LED, and a more complex circuit for controlling a cooling fan with temperature changes. The tutorial also discusses the use of diodes and capacitors to manage voltage and fan operation duration.

What is one of the primary uses of a thermal switch in circuits?

• To increase voltage

• To amplify signals

• To act as a temperature indicator

• To decrease current

What causes the bi-metallic strip in a thermal switch to trigger the switch?

• Pressure change

• Heat causing differential expansion

• Electric current

• Magnetic field

In the temperature indicator circuit, what happens when the thermal switch is not tripped?

• The LED lights up

• Voltage is shunted to ground

• Current flows through the LED

• Voltage builds up at the base of the transistor

What is the function of the 10K resistor in the temperature indicator circuit?

• To increase voltage

• To limit current to the base of the transistor

• To decrease current

• To amplify signals

What component is used to delay the fan operation in the cooling fan control circuit?

• Resistor

• Capacitor

• Inductor

• Diode

What is the purpose of the diode in the cooling fan control circuit?

• To amplify signals

• To prevent voltage backflow

• To increase voltage

• To decrease current

What happens to the fan when the capacitor discharges in the cooling fan control circuit?

• The fan speeds up

• The fan reverses direction

• The fan runs for a while before stopping

• The fan stops immediately

How does the relay-based fan control circuit ensure full power operation?

• By using a larger capacitor

• By using a back EMF diode

• By connecting the fan directly to the power source

• By using a normally closed contact

In the relay-based fan control circuit, what is the role of the back EMF diode?

• To decrease current

• To increase voltage

• To amplify signals

• To protect the relay coil

What is the main advantage of using a relay in the fan control circuit?

• It increases the fan speed

• It decreases the fan noise

• It ensures full power operation

• It reduces power consumption