2N2907 Bipolar PNP Transistor Brief Description

2N2907 Bipolar PNP transistor available in a metal can package, having a high value of current 600mA with a low voltage of 40v. The condition of being forward biased is when the base is connected to the ground or has no supply on it, and as a signal is provided to the base pin it goes reverse-biased. The transistor has having DC current gain value of 100 to 300 which shows the amplification capacity of the transistor. As it is used for amplification and switching.

When the transistor is fully biased it allows a maximum of 500mA current through the collector and provides a voltage (collector to emitter) of 1.6v (max.), this is the Saturation region of the transistor. While the base current is removed the transistor is in the off state it’s in the Cut-off region.

2N2907 transistor as Switch

When used as a switch, can be operated in the saturation and cut-off regions. In the PNP transistor, by default, it’s in the ON state, but not to be said perfectly until the base pin is not grounded. If we provide ground to the base pin then the transistor will be in reverse-biased and said to be turned ON. If supply is provided to the base pin it stops conducting current between the emitter and collector and is said to be in an OFF state. For the protection of the transistor, a resistance was added in series with it. To find the value of that resistor you can use the formula:

R_B= V_BE/ I_B

Where the value of V_BE will be 5v for this transistor. The maximum value of providing base current is 200mA. So, from that you can find the value of resistance to be added in series with it.

2N2907 transistor as Amplifier

When used as an amplifier, can be operated in the active region. When its base is connected to the ground it will allow a high current (600mA) to pass through the collector to the emitter, that’s how it amplifies the current. There are three configurations used in an amplifier circuit common emitter, common base, and common collector. This transistor is used where low-power amplification is needed. It can also amplify the power and current. The amplification factor is usually determined in terms of power, for calculating the current gain we use the formula:

Gain (hfe) = I_C/ I_B

Where IC is the collector current and IB is the base current of the circuit.

Applications

• Where amplification of low power is needed we use this transistor.
• It can also be used in various switching applications.
• Used for making sirens or dual LED or Lamp flashers.
• It can be used in Darlington Pair.