Npn&pnp

I. Transistor basics

2 types of transistors: NPN, PNP

Transistors are usually encapsulated as TO-92, and the following are the components of a physical diagram and components conforming to:

Npn:

When the voltage and current are added to the base, the NPN transistor;

How it works:

Just like a faucet-to give a control switch a little pressure, it puts out water;

Also give a certain voltage and current to the base, it can make the collector of the transistor to the emitter through the current increase, thereby conduction;

Pnp:

PnP is the opposite of the polarity of NPN, so it works as well:

When the valve pressure to close the valve, close the flow, but no pressure to make the water flow through the faucet;

Similarly, when the transistor base gives a certain voltage and current, the transistor is in the cut-off state;

When the base is free of voltage and current, the transistor conduction

(1) The transistor is the basic electronic switch

(2) Transistor is current control current device--base current control collector current

(3) Transistor as a switch, with the transistor cutoff and saturation of 2 working states

The following is a simple analysis of a circuit:

Q1--PNP 3096 R1----100K Euro R2---22K euro R3---470 euro C1---10UF

1. When the switch pbno is disconnected, the LED is lit immediately when the power v+ is just on. Because no voltage is added to the base at this point, the transistor valve is open, that is, the current flows from the transmitter to the collector.

2. When the switch pbno closed, the voltage v+ is added to the PNP base, the transistor valve is closed, the transistor valve cutoff, blocking the current through, the capacitor C1 will be fully charged;

3. When you disconnect the switch again, the C1 stored charge will hold the base voltage, keep the valve off, the transistor cut off, and cut the current.

4. When the capacitance C1 through the resistor R1 discharge, the base voltage will decrease. The transistor is switched on again, and the LED light starts to light up as the current and voltage pass slowly.

The role of R1:

The amount of power stored in the C1 needs to be R1 to release, lowering the transistor base voltage, allowing the valve to be opened again, allowing the current to pass through the transistor.

Npn&pnp