PN2221A Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 40 V
• Collector-Base Voltage, max: 75 V
• Emitter-Base Voltage, max: 6 V
• Collector Current − Continuous, max: 0.8 A
• Collector Dissipation: 0.625 W
• DC Current Gain (h_fe): 40 to 120
• Transition Frequency, min: 250 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-92
• Electrically Similar to the Popular 2N2221A transistor

The PN2221A is manufactured in a plastic TO-92 case. When looking at the flat side with the leads pointed downward, the three leads emerging from the transistor are, from left to right, the emitter, base, and collector leads.
Here is an image showing the pin diagram of this transistor.You can replace the PN2221A with the BC537, BC538, PN2218A or ZTX452.