Using a Transistor as a Switch

How Transistors Work - The Learning Circuit

How to use transistors as a switch - NPN and PNP - Active High and Active Low

Electronic Basics #22: Transistor (BJT) as a Switch

Transistors Explained - How transistors work

How does a transistor work as a switch | What is the application of transistor as a switch

Making logic gates from transistors

Digital Logic Gates from Transistors, AND, NAND, OR, NOR, XOR, XNOR, Buffer, and Inverter