Did you know that TTL chips do not output 5 volts? 74LS, 74HC, and 74HCT all have different input and output thresholds. Switching between logic families can be difficult if you are not careful. In this video, learn how different 7400-series logic families compare with input threshold, output voltage, frequency, rise time, and propagation delay. Check out this TI Application Guide for a great resource on logic families.
Active components like transistors, BJTs, MOSFETs, and integrated circuits (ICs) make it possible to control circuits. This video explains the must-have NPN and PNP BJTs. For MOSFETs there are a couple of N-Channels and P-Channels to consider. Basic ICs include some digital logic stuff from the 7400-family as well as the venerable 555-timer to have on-hand. We did not forget Op-Amps either. Spoiler: We do not recommend the ua741!
Logic probes are great for debugging 7400 series logic chips and digital circuits. In this video, James makes a counter circuit and debugs each stage as he builds, with a Logic Probe. If you are wondering, “do I need a logic probe” this video shows how one can be used and even answers when you should consider buying one.