Users' questions

Can transistors be used as a switch?

Can transistors be used as a switch?

One of the most fundamental applications of a transistor is using it to control the flow of power to another part of the circuit — using it as an electric switch. Driving it in either cutoff or saturation mode, the transistor can create the binary on/off effect of a switch.

How transistor works as a switch?

One of the most common uses for transistors in an electronic circuit is as simple switches. 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 which mode transistor acts as a switch?

A transistor works in active region when worked as an Amplifier. When a transistor works as a Switch it works in Cutoff and Saturation Regions. In the Cutoff State both Emitter Base Junction and Collector Base junctions are reverse biased. But in saturation region both junctions are forward biased.

Can a transistor be used as a diode?

Since a bipolar transistor is essentially two diodes, it can function as such. However, since bipolar transistors are not designed to be used as diodes, using them as diodes might cause a problem in terms of current and other ratings.

Which transistor is better PNP or NPN Why?

A NPN transistor has electrons as majority charge carriers whereas the PNP transistor has holes as majority charge carrier. mobility of electrons is more than hole,so as a result npn transistor are faster than pnp that’s why they are preferred..

What is the symbol of PNP transistor?

The PNP Transistor is denoted by the letters PNP. In the diagram below, the symbol for a PNP transistor is depicted. In a PNP transistor, the current flows from the emitter to the collector, as shown by the inward arrow.

Which transistor is mostly used?

The MOSFET is by far the most widely used transistor for both digital circuits as well as analog circuits, accounting for 99.9% of all transistors in the world. The bipolar junction transistor (BJT) was previously the most commonly used transistor during the 1950s to 1960s.

Can you use two diodes as a transistor?

There’s a transistor-model which is explained with two diodes and you can measure the two diodes in the transistor but you cannot make a transistor with two diodes. The assymetrical doping of collector and emitter and the very thin shared base differs the real transistor from your diodes.

What is the difference between a diode and a transistor?

Put simply, a diode is a two-terminal semiconductor device and a transistor is a three-terminal semiconductor device. A diode can allow the flow of current in one direction while blocking the flow of current in the other direction.

When does a transistor act like a switch?

If a positive signal applied at the input terminal then it acts like a closed switch. When the transistor operating as switch, in the cut off region the current through the transistor is zero and voltage across it is maximum, and in the saturation region the transistor current is maximum and voltage across is zero.

How is a transistor used as an AC signal amplifier?

When used as an AC signal amplifier, the transistors Base biasing voltage is applied in such a way that it always operates within its “active” region, that is the linear part of the output characteristics curves are used.

When does the gain formula for a transistor no longer apply?

In other words, once a transistor switch reaches the saturation point, the gain formula I C = Beta x I B no longer applies because the voltage drop across the collector/emitter terminals (V CE (sat)) has reached its lowest saturation voltage of .1V.

How does a Darlington transistor work as a switch?

Darlington Transistors simply contain two individual bipolar NPN or PNP type transistors connected together so that the current gain of the first transistor is multiplied with that of the current gain of the second transistor to produce a device which acts like a single transistor with a very high current gain for a much smaller Base current.