BC549B NPN transistor

A BC549B is a general-purpose NPN transistor. It comes in a TO-92 packaging style. 

You can use this in the following applications;

1. General electronics projects.
2. AF input and driver stages - for low noise input.
3. Complementary transistors to BC556, BC557, BC560.

The following are some detail about its working;

1. Collector base voltage: 30V
2. Collector emitter voltage: 30V
3. Emitter base voltage: 5V
4. Collector current up to 200mA - absolute rating. But you can draw 100mA continuously.

In the TO-92 packaging, you can find the following pin configuration;

1. The Emitter at pin 1.
2. The Base at pin 2.
3. The Collector at pin 3.

What is an NPN transistor?

Any BJT transistor is a type of transistor in which one p-type material dopes with two n-type materials. The materials' configurations may vary depending on their application.