Transistor Assortment, Npn Transistor Transistors Assortment Kit for Industry for Plug Transistor for PNP Transistor for 2n3904 Npn Transistor: Amazon.com: Industrial & Scientific
Amazon.com: NPN/PNP to NPN 5V/24V Signal Conversion Board Amplifier Circuit High Reliability 8 Channel Level Voltage Conversion Module for Matching : Electronics