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How a transistor is able to work as a switch?
With a zero signal applied to the Base of the transistor it turns “OFF” acting like an open switch and zero collector current flows. With a positive signal applied to the Base of the transistor it turns “ON” acting like a closed switch and maximum circuit current flows through the device.
In which mode the transistor acts as open switch?
Detailed Solution
| Mode | EB Biasing | Application |
|---|---|---|
| Cut off | Reverse | Open or OFF switch |
| Active | Forward | Amplifier |
| Reverse e Active | Reverse | Not much Useful |
| Saturation | Forward | Closed or ON Switch |
What kind of transistors are used in PWM?
PWM does make use of transistors, but in a different way, as explained below. PWM Motor Controller Example.
How are input and output transistors used in a switch?
The first or “input” transistor receives the input signal to its Base. This transistor amplifies it in the usual way and uses it to drive the second larger “output” transistors. The second transistor amplifies the signal again resulting in a very high current gain.
How is PWM used in a PC fan?
Then I will implement a simple form of PWM (pulse-width modulation) to control the fan’s speed. This demonstrates the ability of transistors to use low-voltage, low-current signal lines (such as a parallel port or microcontroller IO line) to control higher voltage, higher current devices like motors (in this case, PC fans).
What happens when a positive signal is applied to a transistor?
With a zero signal applied to the Base of the transistor it turns “OFF” acting like an open switch and zero collector current flows. With a positive signal applied to the Base of the transistor it turns “ON” acting like a closed switch and maximum circuit current flows through the device.