How can a transistor be used as an amplifier or a switch?

The transistor will operate as an amplifier or other linear circuit if the transistor is biased into the linear region. The transistor can be used as a switch if biased in the saturation and cut-off regions. This allows current to flow (or not) in other parts of a circuit.

How can a transistor be used as a relay?

A typical relay switch circuit has the coil driven by a NPN transistor switch, TR1 as shown depending on the input voltage level. When the Base voltage of the transistor is zero (or negative), the transistor is cut-off and acts as an open switch.

How transistor can be used as 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.

Which is faster BJT or FET?

because of low ohmic behavior of the bipolar transistors, its parasitic capacitances can be charged and discharged with very high speed compared to the MOSFET transistors. MOSFET is a low power consumption but switing time is faster in the case of BJT.

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 a transistor be used as an amplifier?

A transistor acts as an amplifier by raising the strength of a weak signal. The DC bias voltage applied to the emitter base junction, makes it remain in forward biased condition. Thus a small input voltage results in a large output voltage, which shows that the transistor works as an amplifier.

Can a MOSFET replace a relay?

Yes. Relays 1, 6, and 7 can be replaced by a P-MOSFET, source to +12V with drain being the output (if you have a 12V control signal). This will give an inverted control (0V will turn on the P-MOSFET). If you want 0V to turn off the switch then you can add an NPN BJT or N-MOSFET driver.

Should I use a transistor or a relay?

Generally, if you are switching DC motors, solenoids, or other high-current DC devices which create motion, it’s better to use a switching transistor than a relay. The ideal way to control a motor is with an H-bridge, which is an array of transistors that lets you control not only speed but also direction.

Can capacitor be used as a switch?

A switched capacitor is an electronic circuit element used in discrete time signal processing systems. Usually, non-overlapping signals are used to control the switches, often termed Break before Make switching, so that all switches are open for a very short time during the switching transitions.

Why is FET faster than BJT?

Whereas in the case of an FET, it is decided by the gate to source resistance. Since the input for a BJT is a forward biased diode, the resistance is low. In the case of an FET, THE DRAIN SOURCE CAPACITAANCE IS QUITE SMALL hence the upper 3 dB frequency is quite large yielding a large bandwidth.

Can a PNP switch be used as a transistor?

In conclusion, if a control signal at the base input is 0 volts. It will provide an ON signal. Because we use a PNP switch in this example circuit. Similarly, it will remain off, its control signal is logic HIGH. This diagram shows the interfacing of an Arduino with an NPN transistor and a motor.

What happens when a switch is closed on a transistor?

Therefore, the circuit acts as open-circuit and the LED becomes OFF. When the switch is closed, base current starts flowing through the transistor and then drives into saturation results to LED become ON. Resistors are placed to limit the currents through the base and LED.

Can a transistor be used as a solid state switch?

However, both the NPN & PNP type bipolar transistors can be made to operate as “ON/OFF” type solid state switch by biasing the transistors Base terminal differently to that for a signal amplifier. Solid state switches are one of the main applications for the use of transistor to switch a DC output “ON” or “OFF”.

How is a bipolar transistor used as a switch?

If the circuit uses the Bipolar Transistor as a switch, then the transistor’s biasing, whether NPN or PNP, is designed to operate the transistor on both sides of the previously seen “I-V” characteristic curves. The transistor switch operating areas are referred to as the Saturation Region and the Cut-off Area.