Electronic Fundamentals: Semiconductors, Logic and Digital Systems
Semiconductor devices
Understand the diode (one-way conduction, used for rectification and flyback protection), the transistor as a switch and amplifier, and the thyristor as a latching switch. Know the meaning of forward and reverse bias, and why a flyback diode protects a circuit when an inductive load is switched off.
Digital logic
Know the basic gates (AND, OR, NOT, NAND, NOR, XOR) and how to build a truth table. Understand binary number representation and simple conversion. Recognise that NAND and NOR are universal gates. Understand the difference between analogue and digital signals and the role of the ADC and DAC.
Aircraft electronic systems
Understand the principles of line-replaceable units, the ARINC data bus concept, and the difference between a bus and a point-to-point wire. Know the basics of electromagnetic interference, shielding and bonding, and why software and hardware configuration control matters.
Traps
- Assuming a transistor is only an amplifier; in aircraft it is often a switch.
- Confusing the truth table of XOR with OR; XOR is true only when inputs differ.
- Forgetting that a diode's reverse breakdown is not normal operation.
Worked example
An AND gate has inputs A=1, B=0. Output = 0. A NAND gate with the same inputs gives 1. If a question asks for the output of a two-input gate, write the truth table before answering; this avoids confusing OR and XOR.