How does a transistor turn on and off?

In short, a transistor conducts current across the collector-emitter path only when a voltage is applied to the base. When no base voltage is present, the switch is off. When base voltage is present, the switch is on. In an ideal switch, the transistor should be in only one of two states: off or on.

How many types of transistors are there?

Transistors are broadly divided into three types: bipolar transistors (bipolar junction transistors: BJTs), field-effect transistors (FETs), and insulated-gate bipolar transistors (IGBTs). A bipolar transistor is a type of transistor that uses both electrons and holes as charge carriers.

What is a capacitor What does it do?

A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electrostatically in an electric field. Unlike a resistor, a capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

When operated in cutoff and saturation the transistor acts like a?

The four transistor operation modes are: Saturation — The transistor acts like a short circuit. Current freely flows from collector to emitter. Cut-off — The transistor acts like an open circuit.

What is the difference between transistor and MOSFET?

The only difference is in function. A MOSFET is a type of transistor commonly used in switching/amplifier type applications, as they are usually designed for higher power use (so called “high power” transistors are mostly MOSFET and Darlington type).

How does MOSFET transistor work?

It works by varying the width of a channel along which charge carriers flow (electrons or holes). The charge carriers enter the channel at source and exit via the drain. The width of the channel is controlled by the voltage on an electrode is called gate which is located between source and drain.

What is BC548 transistor?

The BC548 is a general-purpose NPN bipolar junction transistor commonly used in European and American electronic equipment. It is notably often the first type of bipolar transistor hobbyists encounter and is often featured in designs in hobby electronics magazines where a general-purpose transistor is required.

What is hFE BJT?

hFE is an abbreviation, and it stands for “Hybrid parameter forward current gain, common emitter”, and is a measure of the DC gain of a junction transistor.

What happens when a transistor is turned on and off?

In practice when the transistor is turned “OFF”, small leakage currents flow through the transistor and when fully “ON” the device has a low resistance value causing a small saturation voltage ( VCE ) across it.

How does a transistor control the current through an led?

That’s the sum of the current through the LEDs. A transistor is current controlled, but that’s not always handy, and therefore we will often make it voltage controlled by adding a resistor to the base. The resistor will turn a voltage difference into a current, again Ohm’s Law.

How can I make a transistor turn on at higher voltage?

So, increasing the base resistor (R2) will make the transistor turn on at higher voltage than 1.5V). If you want the LED to turn on when the voltage is below 1.5V *that is, invert what it is now) then you can do it like this: Now when the transistor turns on, it shorts out the LED so the LED goes dark.

How does a D3 transistor work?

A transistor is current controlled, but that’s not always handy, and therefore we will often make it voltage controlled by adding a resistor to the base. The resistor will turn a voltage difference into a current, again Ohm’s Law. So by driving the CTRL input with a voltage that will create a base current, which will cause a current through LED D3.