Chapter 1 · Semiconductor Materials and the PN Junction
| Item | Fact / typical value | Topic |
|---|---|---|
| Valence electrons | conductors 1–3 · semiconductors 4 · insulators full shell | 4.1.1 |
| Band gap | Si ≈ 1.1 eV · Ge ≈ 0.67 eV · insulators > 5 eV | 4.1.1 |
| N-type dopants (donors) | pentavalent: phosphorus, arsenic, antimony | 4.1.1 |
| P-type dopants (acceptors) | trivalent: boron, gallium, indium, aluminium | 4.1.1 |
| Majority / minority carriers | N-type: electrons / holes · P-type: holes / electrons | 4.1.1 |
| Barrier potential | Si ≈ 0.6–0.7 V · Ge ≈ 0.2–0.3 V at 25 °C | 4.1.1 |
| Barrier vs temperature | falls ≈ 2 mV per °C | 4.1.1 |
| Reverse leakage | Si nanoamps · Ge microamps · ≈ doubles every 10 °C | 4.1.1 |
| Breakdown | Zener effect below ≈ 5 V (heavy doping) · avalanche above | 4.1.1 |
| Max junction temperature | Si ≈ 150–200 °C · Ge ≈ 75–100 °C | 4.1.1 |
Chapter 2 · Diodes: Symbols, Characteristics and Ratings
| Item | Fact / typical value | Topic |
|---|---|---|
| Diode symbol | triangle = anode (P) · bar = cathode (N) · arrow = conventional current | 4.1.1 |
| Cathode markings | band / line · standard stud = K ('R' = A) · LED short leg & flat | 4.1.1 |
| Type prefixes | 1N diode · 2N transistor · 3N 4-terminal · A = Ge, B = Si (BY rectifier, BZ Zener) | 4.1.1 |
| Forward drop | Si ≈ 0.7 V · Ge ≈ 0.3 V · Schottky ≈ 0.2–0.4 V | 4.1.1 |
| PIV / VRRM | max repeated reverse voltage — keep well below VBR | 4.1.1 |
| 1N4001…1N4007 | 1 A rectifiers · PIV 50 V … 1 000 V | 4.1.1 |
| Series diodes | equalising resistors (+ capacitors) across each | 4.1.1 |
| Parallel diodes | small series (ballast) resistor in each branch | 4.1.1 |
| Rectifier ripple on 400 Hz | half-wave 400 Hz · full-wave/bridge 800 Hz · 3-phase bridge 2 400 Hz | 4.1.1 |
| PIV per diode | half-wave Vpk · centre-tap 2 Vpk · bridge Vpk | 4.1.1 |
| DMM diode test | good Si 0.5–0.8 V / OL · short 0 / 0 · open OL / OL | 4.1.1 |
Chapter 3 · Special Diodes, Thyristors, LEDs and Photodiodes
| Item | Fact / typical value | Topic |
|---|---|---|
| Zener | reverse biased · shunt across load + series R · PZ = VZ × IZ | 4.1.1 |
| Zener temperature coefficient | − below ≈ 5 V (Zener) · + above ≈ 6 V (avalanche) · ≈ 0 near 5–6 V | 4.1.1 |
| Schottky | metal–semiconductor · 0.2–0.4 V · fastest · higher leakage | 4.1.1 |
| LED forward voltage | IR ≈ 1.2–1.5 V · red ≈ 2 V · blue/white ≈ 3–3.6 V | 4.1.1 |
| LED resistor | R = (Vs − VF) ÷ IF · 28 V, 2 V, 20 mA → 1.3 kΩ, ≈ 0.5 W | 4.1.1 |
| LED reverse rating | ≈ 5 V | 4.1.1 |
| Photodiode | reverse biased · current ∝ light · dark current = leakage | 4.1.1 |
| Varactor | reverse biased · C falls as VR rises · tuning/VCO | 4.1.1 |
| Varistor (MOV) | across the supply · clamps both polarities · degrades with surges | 4.1.1 |
| SCR | PNPN · A, K, G · + gate pulse ON · latches · OFF when IA < IH | 4.1.1 |
| Triac / diac | triac: MT1, MT2, G, both ways · diac: ≈ 30 V breakover | 4.1.1 |
Chapter 4 · Transistors
| Item | Fact / typical value | Topic |
|---|---|---|
| BJT symbol | arrow on emitter · NPN points out · PNP points in | 4.1.2 |
| Construction | emitter heavy doping · base thin, light · collector largest | 4.1.2 |
| Active bias | B–E forward (≈ 0.6–0.7 V Si) · C–B reverse | 4.1.2 |
| Currents | IE = IB + IC · β = IC ÷ IB (20–500) · α = IC ÷ IE (0.95–0.99) | 4.1.2 |
| Regions | cut-off = OFF · active = amplifier · saturation = ON (VCE ≈ 0.2 V) | 4.1.2 |
| VEBO | only ≈ 5–7 V | 4.1.2 |
| Packages | TO-92 order varies · TO-220 tab = C · TO-3 case = C | 4.1.2 |
| FET | gate, drain, source · voltage-controlled · very high input impedance | 4.1.2 |
| JFET / MOSFET | JFET normally ON · enhancement MOSFET normally OFF · MOS gate ESD-sensitive | 4.1.2 |
| Darlington | gain ≈ β1 × β2 · VBE ≈ 1.2–1.4 V | 4.1.2 |
| Configurations (B2) | CE: inverts (180°) · CC: emitter follower, gain ≈ 1 · CB: high frequency | 4.1.2 |
Chapter 5 · Integrated Circuits and Logic Gates
| Item | Fact / typical value | Topic |
|---|---|---|
| IC | complete circuit on one silicon chip · reliable · replace, not repair | 4.1.3 |
| Scale of integration | SSI ≤ ≈10 · MSI ≈10–100 · LSI ≈100–10 000 · VLSI > 10 000 gates | 4.1.3 |
| DIP | 2.54 mm pitch · pin 1 notch/dot · anticlockwise from above | 4.1.3 |
| TTL levels | 5 V · input LOW < 0.8 V, HIGH > 2.0 V · output < 0.4 V / > 2.4 V | 4.1.3 |
| CMOS levels | ≈ 30% / 70% of supply · tie unused inputs | 4.1.3 |
| AND / OR | AND: 1 if all 1 · OR: 1 if any 1 | 4.1.3 |
| NAND / NOR | NAND: 0 only if all 1 · NOR: 1 only if all 0 · both universal | 4.1.3 |
| XOR / XNOR | XOR: 1 if different · XNOR: 1 if same (equality) | 4.1.3 |
| IEC symbols | & AND · ≥1 OR · =1 XOR · 1 buffer · ○ inversion | 4.1.3 |
| De Morgan | A·B = A + B · A + B = A·B | 4.1.3 |
Chapter 6 · Linear Circuits and Operational Amplifiers
| Item | Fact / typical value | Topic |
|---|---|---|
| Op-amp inputs | − inverting · + non-inverting · Vout = AOL × (V+ − V−) | 4.1.3 |
| Ideal op-amp | gain ∞ · Zin ∞ · Zout 0 · bandwidth ∞ | 4.1.3 |
| 741 typical | AOL ≈ 200 000 · Zin ≈ 2 MΩ · Zout ≈ 75 Ω | 4.1.3 |
| 741 pinout | 2 (−), 3 (+), 6 out, 7 V+, 4 V−, 1/5 offset null | 4.1.3 |
| Comparator | open loop · output ±Vsat · thresholds and warnings | 4.1.3 |
| Inverting amplifier | gain −Rf/Rin · 180° · virtual earth | 4.1.3 |
| Non-inverting amplifier | gain 1 + Rf/R1 · in phase · high Zin | 4.1.3 |
| Voltage follower | gain 1 · buffer | 4.1.3 |
| Integrator / differentiator (B2) | C in feedback = integrator · C at input = differentiator | 4.1.3 |
| Feedback (B2) | negative: stable, less gain · positive: oscillators, Schmitt | 4.1.3 |
Chapter 7 · Printed Circuit Boards
| Item | Fact / typical value | Topic |
|---|---|---|
| PCB functions | mechanical support + electrical interconnection | 4.2 |
| FR-4 | woven glass + epoxy · flame retardant · ≈ 1.6 mm | 4.2 |
| Copper weight | 1 oz/ft² ≈ 35 µm · 2 oz ≈ 70 µm | 4.2 |
| Vias | through (all layers) · blind (outer→inner) · buried (inner only) | 4.2 |
| Designators | R, C, L, D/CR, Q, U/IC, J/P, K, F, T, Y | 4.2 |
| Soldering | THT: wave · SMT: paste + reflow · BGA: X-ray inspection | 4.2 |
| Conformal coating | acrylic, PU, silicone, epoxy, parylene · UV inspection · re-apply same type | 4.2 |
| ESD | feel ≈ 3 000 V · damage < 100 V possible · latent damage · strap via 1 MΩ | 4.2 |
| Repair standards | CMM + IPC-A-610, IPC-7711/7721, J-STD-001 | 4.2 |
Chapter 8 · Servomechanisms: Principles and Sensors
| Item | Fact / typical value | Topic |
|---|---|---|
| Open vs closed loop | open: no feedback · closed: feedback compared with demand | 4.3 |
| Servomechanism | closed loop + mechanical position + power amplification | 4.3 |
| Error / null | error = demand − actual · null = zero error, motor stops | 4.3 |
| Damping | under: overshoot · critical: fastest, none · over: sluggish · rate feedback | 4.3 |
| Hunting | continuous oscillation about null — gain too high, damping too low, backlash | 4.3 |
| Deadband | no response near null · too narrow → hunting · too wide → inaccuracy | 4.3 |
| LVDT | AC primary + secondaries in opposition · null at centre · phase = direction | 4.3 |
| Proximity sensor | coil + steel target · PSEU near/far/fault · set the gap | 4.3 |
| Speed pickup | pulse frequency ∝ speed (N1/N2, wheel speed) | 4.3 |
| Encoders | incremental: A/B 90° → direction · absolute: Gray code, one bit per step | 4.3 |
Chapter 9 · Synchros, Resolvers and Remote Transmitters
| Item | Fact / typical value | Topic |
|---|---|---|
| Synchro rotor / stator | rotor: 1 winding R1-R2 · stator: S1, S2, S3 at 120°, star | 4.3 |
| Synchro excitation | 26 V or 115 V AC, 400 Hz · L-L max 11.8 V / 90 V | 4.3 |
| Stator voltages | in time phase — amplitudes vary with angle (not 3-phase) | 4.3 |
| Torque system | TX → TR · light loads (pointers) · damper | 4.3 |
| Control system | CX → CT (rotor not excited) → amp → motor → null | 4.3 |
| Differential | 3 + 3 windings · receiver shows θ1 ± θ2 | 4.3 |
| Resolver | windings at 90° · outputs ∝ sin θ, cos θ | 4.3 |
| DC selsyn | 28 V DC · resistance + brushes · PM pointer | 4.3 |
| Magnesyn | PM rotor in AC-excited toroidal coil · inductance transmitter | 4.3 |
| Capacitance fuel probe | K fuel ≈ 2.1, air 1, water ≈ 80 · mass via density compensation | 4.3 |
| Swapped leads (B2) | S1↔S3 reversed · R1↔R2 180° · rotated S leads 120° | 4.3 |
Chapter 10 · Extra: Radio Communication, ELT and ADS-B
| Item | Fact / typical value | Topic |
|---|---|---|
| Radio wave speed / wavelength | c ≈ 300 000 km/s · λ = c ÷ f · 121.5 MHz ≈ 2.47 m | X |
| Bands | LF/MF NDB · HF 3–30 MHz · VHF 30–300 · UHF 0.3–3 GHz · SHF 3–30 GHz | X |
| Aviation frequencies | VOR/LOC 108–118 · comm 118–137 (AM) · GS 329–335 · DME 962–1 213 · XPDR 1 030/1 090 · ELT 406 | X |
| Propagation | ground wave LF/MF · sky wave HF (skip zone) · space wave VHF+ ≈ 1.23 √h nm | X |
| Modulation | AM: VHF voice · FM: low noise · SSB: HF, upper sideband | X |
| Antennas | dipole λ/2 · Marconi λ/4 + skin · loop nulls (ADF) · VHF comm vertical, VOR horizontal | X |
| Coax | 50 Ω (75 Ω video) · VSWR 1:1 ideal | X |
| ADS-B | GNSS-dependent · 1090 ES worldwide · UAT 978 MHz USA · ≈ 2 per second | X |
| ELT | 406 MHz → Cospas-Sarsat · 121.5 homing · AF/AP/AD/S · arrow forward, aft mounting | X |
| ELT battery and tests (FAA) | 1 h use or 50% life · inspect 12 months · test first 5 min after the hour | X |