How does bipolar transistor function as a switch?

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. Because a transistor’s collector current is proportionally limited by its base current, it can be used as a sort of current-controlled switch.

At what current does a transistor turn on?

The diode only needs 0.6V to turn on, more voltage than that means more current. Some transistors may only be rated for a maximum of 10-100mA of current to flow through them. If you supply a current over the maximum rating, the transistor might blow up.

When a transistor is usually switched on it is said to be?

Answer: Therefore the transistor is switched “Fully-ON”. The definition of “saturation region” or “ON mode” when using a bipolar NPN transistor as a switch as being, both the junctions are forward biased, IC = Maximum and VB > 0.7v.

What are the two main tasks or roles that bipolar transistors do?

Bipolar junction transistors can increase both analogue and digital signals, as well as having the ability to switch DC power or to function as an oscillator. While BJTs are designed primarily to amplify (analogue) current, they can also function as an electronic (digital) switch in circuitry.

How do you know if a transistor is working?

Hook the positive lead from the multimeter to the to the BASE (B) of the transistor. Hook the negative meter lead to the EMITTER (E) of the transistor. For an good NPN transistor, the meter should show a voltage drop between 0.45V and 0.9V. If you are testing PNP transistor, you should see “OL” (Over Limit).

How do transistors 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.