简单的说- 2N3904 NPN晶体管

　　简单的说- 2N3904 NPN晶体管

　　2N3904 NPN晶体管是一个非常受欢迎的，是作为一个简单的电子开关或放大器，可处理200马（绝对值）和高达100 MHz的频率作为一个放大器。

　　Figure 1： An illustration of the pin out of a standard TO-92 package for Digi-Key part number 2N3904FS-ND： E = Emitter， B = Base， C = Collector.

　　Figure 2 shows a circuit example which turns on the collector emitter junction by energizing the base or biasing the transistor to turn it on by bringing 5 volts to the base via a slide switch. This example lights an LED which is considered to be the load in this case. The proper use of resistors to prevent over current draw is required when biasing the base. I used leaded parts in a bread board to test my example circuit. Most engineers will use surface-mount components （much smaller size then a TO-92 package） when it comes to using transistors in a new product design going to market. Here is a link that shows various package sizes for 3904 transistors.