The S9012 is a type of NPN bipolar junction transistor (BJT) commonly used for low to medium current amplification and switching purposes. Here are the key details:
Type: NPN transistor
Maximum Collector Current (Ic): ~0.8 A
Maximum Collector-Emitter Voltage (Vce): 40 V
Maximum Collector-Base Voltage (Vcb): 60 V
Maximum Power Dissipation (Ptot): ~0.8 W
DC Current Gain (hFE): 70–400 (depending on the manufacturer and operating point)
Package: TO-92
 
Applications:
Signal amplification in audio circuits
Switching low-power loads
General-purpose electronic circuits