2N2222A by Texas Instruments is a small signal NPN bipolar junction transistor (BJT) with a max collector-emitter voltage of 40V and a max collector current of 0.8A. It is commonly used for switching applications due to its fast turn on/off times (35ns/285ns) and high transition frequency (300MHz).
BSS138LT1G by Onsemi is a N-CHANNEL FET with 50V DS Breakdown Voltage, 0.2A Drain Current, and 3.5 ohm On Resistance. Ideal for SWITCHING applications due to its ENHANCEMENT MODE operation and built-in DIODE. Operates b/w -55 to 150 °C with small outline package style for surface mount assembly.