Electronics Honor

Vocational Activities

Requirements

1. Design a simple schematic diagram, such as a light sensor that controls the turning on of a lamp; use the correct symbols to represent each of them.

   Answer: You should design a schematic diagram: a LIGHT SENSOR that turns on a lamp when it gets dark. Components: LDR (light-dependent resistor), resistor R, BC547 transistor (electronic switch), relay or TRIAC (lamp actuation), protection diode. — The LDR (Light Dependent Resistor) is a resistor whose value changes with the incident light: high in the dark (~1 MΩ), low in the light (~100 Ω). Combined with a transistor, it forms a circuit that activates the relay when the resistance reaches a certain threshold. This is a classic basic electronics project, taught in technical schools and fundamental for understanding simple digital circuits.

2. Demonstrate the correct way to solder and desolder electronic components, as well as the precautions to be taken to avoid rendering them useless.

   Answer: SOLDERING: heat the iron to 350°C, touch the tip to the contact and the component's lead for 1-2 seconds, apply solder (60% tin/40% lead, or lead-free), remove the solder, then remove the iron. Result: a shiny, conical joint. DESOLDERING: heat the joint and use a desoldering tool (solder sucker) or desoldering braid to remove it. — A cold solder joint (dull and grainy) indicates insufficient heating — it can result in poor contact. Sensitive components (ICs, MOSFETs) only withstand 3-5 seconds at 350°C before burning. RoHS (EU, 2006) limited lead in electronics for sustainability — lead-free solder (tin/silver/copper) is the modern standard. An iron with a temperature regulator is essential for quality.

3. What are the main safety rules to be observed when handling electronic circuit boards in order to avoid damage to them?

   Answer: Rules: 1) GROUNDED ANTISTATIC WRIST STRAP when handling (static burns components); 2) DO NOT TOUCH traces and components directly with your fingers (oiliness oxidizes); 3) HANDLE by the edges of the board, holding it by the corners; 4) STORE in an antistatic bag when not in use; 5) CLEAN ENVIRONMENT without high humidity (avoids short circuits and oxidation); 6) GROUNDED TOOLS; 7) DO NOT BEND the board. — ESD (Electrostatic Discharge) is the leading cause of failures in electronics — a simple 30V discharge already damages integrated circuits (which operate at 3-5V). The antistatic wrist strap equalizes the technician's electrical potential with that of the board via a 1 MΩ resistor. Semiconductor industries work in clean rooms with conductive flooring and controlled humidity to constantly prevent ESD.

4. Research the development of the incandescent valve: how it was discovered, what uses it had, and what types of materials were used by its inventor.

   Answer: The 'incandescent valve' (incandescent lamp / later the thermionic valve derived from it) had its development linked to Thomas Edison, who in 1879 presented the first commercially viable incandescent lamp (Joseph Swan worked in parallel in England). DISCOVERY: light was produced by the passage of electric current through a thin filament inside a glass bulb without air; the filament heated until it became incandescent and emitted light. Edison tested thousands of materials (more than 6,000) seeking a durable filament, arriving at carbonized bamboo and then carbon thread. USES: residential, commercial, and public lighting, replacing the gas lamp and candles; it was the basis of the electrical industry. The 'Edison effect' observed in this bulb (emission of electrons from the heated filament) gave rise, years later, to the thermionic valve (Fleming's vacuum diode, 1904) used in radios and the first computers. MATERIALS used by the inventor: filament (first carbon/carbonized bamboo, then tungsten from 1906-1910), glass bulb sealed in a vacuum (later filled with an inert gas such as argon/nitrogen to prolong the filament's life), and a brass metal base for the electrical contact. — Edison's first lamp lasted 14.5 hours (October 21, 1879). In 1880, he increased it to 1,200 hours with a bamboo filament. Tungsten (discovered in 1906 by William Coolidge) revolutionized it due to the high temperature it can withstand (3,422°C). Today incandescent lamps are banned in several countries for low energy efficiency — replaced by more efficient LEDs and fluorescent lamps.

5. List the main units of measurement found in electronics and know how to identify them on each component.

   Answer: Main units: 1) VOLT (V) — voltage/potential difference; 2) AMPERE (A) — electric current; 3) OHM (Ω) — resistance; 4) WATT (W) — power; 5) FARAD (F) — capacitance; 6) HENRY (H) — inductance; 7) HERTZ (Hz) — frequency. Resistors marked in Ω, capacitors in F (µF/nF/pF), inductors in H (µH/mH), transistors in gain (β) or voltage. — Resistors use a color code (4 or 5 bands) to indicate the value in ohms. Electrolytic capacitors come with a value in µF/nF and a working voltage (16V, 25V, 50V). Inductors are specified in mH or µH. The units form the SI system (International System). 1 farad is a very large unit — real capacitors are in microfarads (µF = 10⁻⁶F).

6. Research what an N element and a P element are. What materials are they made of and what do these elements do in electronic devices?

   Answer: An N-type and a P-type (semiconductor) element are doped semiconductor materials, the basis of electronic components. N ELEMENT (negative): a pure semiconductor (silicon or germanium) doped with pentavalent atoms (phosphorus, arsenic, antimony); these atoms have one extra electron, generating an EXCESS OF FREE ELECTRONS (negative charge carriers). P ELEMENT (positive): a semiconductor doped with trivalent atoms (boron, aluminum, gallium); one electron is missing, creating 'HOLES' (absences of an electron that act as positive charge carriers). WHAT THEY DO: when joining a P crystal and an N crystal, a P-N JUNCTION is formed, which conducts current in one direction and blocks it in the other — it is the basis of the diode. Combinations of these junctions form transistors (NPN/PNP), LEDs, solar cells, and integrated circuits, that is, practically all modern electronic devices depend on the N and P elements. — Silicon is the most used semiconductor (98% of chips). Doping creates controlled conductivity — pure silicon is an insulator; with 1 atom of phosphorus in 100 million of silicon, it becomes a conductor. The P-N junction allows current to pass in one direction and blocks it in the other (diode). By combining P-N-P or N-P-N junctions, the transistor emerges — an invention of the 20th century (1947, Bell Labs).

7. What is a logic gate? Define each of them below, illustrating them:
   • AND
   • OR
   • NOR
   • NAND
   • XOR

   Answer: A LOGIC GATE is a circuit that executes a Boolean operation (0 or 1). 1) AND — output 1 only if ALL inputs are 1; 2) OR — output 1 if AT LEAST ONE input is 1; 3) NOR — the inverse of OR (output 0 if any input is 1); 4) NAND — the inverse of AND (output 0 only if all inputs are 1); 5) XOR — output 1 if the inputs are DIFFERENT (one 1 and the other 0). The bases of digital circuits. — Logic gates are implemented with transistors in ICs such as the 7400 (NAND), 7402 (NOR), 7408 (AND), 7432 (OR), 7486 (XOR). Every complex computational operation (CPU, memory, calculator) reduces to combinations of these 5 basic gates. NAND and NOR are called 'universal gates' because any logic circuit can be built using just one of them.

8. Know diodes and how they work.

   Answer: A DIODE is a semiconductor component that allows current to pass in ONLY ONE DIRECTION (from the anode to the cathode). It works as a P-N junction: when forward-biased (P+, N-), it conducts; when reverse-biased (P-, N+), it blocks. Types: rectifier diode (1N4007), LED (emits light), Zener (voltage regulator), Schottky (fast). — Forward voltage drop: silicon 0.7V, germanium 0.3V, LEDs between 1.8V (red) and 3.4V (blue/white). The Zener diode is manufactured to 'break down' at a specific voltage, used as a regulator. Rectifier bridges (4 diodes) convert AC to DC — the basis of all power supplies. The LED revolutionized lighting due to its efficiency (90% less consumption than incandescent).

9. Design, draw, prepare, and assemble a printed circuit board.

   Answer: You should: 1) DESIGN in software (KiCad, Eagle, Proteus) the schematic and the layout of the traces; 2) PRINT the layout on a transparency or use thermal transfer; 3) PREPARE a phenolic/fiberglass board with copper; 4) TRANSFER the layout to the board; 5) ETCH with ferric chloride, removing the unprotected copper; 6) CLEAN and drill the points for the components. — KiCad is professional free software for PCBs. Ferric chloride etches exposed copper in 15-30 minutes. Phenolic is cheaper (~R$5/small board), fiberglass (FR-4) is more resistant. A manual drill or Dremel for 0.8-1mm holes. Commercial PCBs use a green solder mask, but amateur boards can do without it. After assembling, test continuity with a multimeter before powering on.

10. Build a simple AM or FM receiver and understand how it works.

    Answer: Build a simple receiver: a basic AM one needs an antenna (a long wire), a tuned coil (inductor + variable capacitor), a detector diode (1N34 germanium), a filter capacitor, a crystal earphone/earpiece. FM requires a more complex circuit with a local oscillator. Use educational kits (TEA5767 IC or TDA7088). — AM (Amplitude Modulation) operates at 535-1605 kHz; FM (Frequency Modulation) at 88-108 MHz. The AM crystal receiver was the first popular radio (1920s); it worked without a battery — the energy of the wave itself produced the sound. FM has superior quality because it is immune to electrical interference, but a shorter range. The germanium diode (1N34) is preferred for its low voltage drop (0.3V), picking up weak signals.

11. Demonstrate the correct use of the most common tools and measuring devices in an electronics laboratory (oscilloscope, multimeter, etc.).

    Answer: Tools: 1) MULTIMETER — measures voltage (V), current (A), resistance (Ω), continuity. Select the function and scale first; 2) OSCILLOSCOPE — visualizes the waveform over time (X axis: time, Y axis: voltage); 3) SOLDERING IRON with a regulator; 4) needle-nose PLIERS, cutting pliers; 5) wire STRIPPER; 6) bench POWER SUPPLY with variable voltage. Each tool has a specific function and its own safety requirements. — A digital multimeter has protection against polarity reversal in most modern models. A typical digital oscilloscope (Tektronix, Rigol) reaches 100 MHz of bandwidth — sufficient for audio and digital signals. The oscilloscope's 10x probe lowers the impedance on the circuit under test. A typical bench power supply has 0-30V and 0-3A with automatic short-circuit protection.

12. Know the main areas of application of electronics, explaining one of them.

    Answer: Main areas: 1) COMPUTING (computers, smartphones); 2) TELECOMMUNICATIONS (radio, TV, internet, cell phone); 3) MEDICINE (X-ray, ultrasound, MRI, pacemaker); 4) INDUSTRIAL AUTOMATION (PLC, robots, sensors); 5) AUTOMOTIVE (electronic injection, ABS, airbag, infotainment); 6) AEROSPACE (navigation systems, satellites); 7) ENTERTAINMENT (TV, console, audio). — Modern pacemakers have a lithium battery with an 8-10 year life, sensors that detect the heartbeat, a microcontroller that fires pulses when necessary, and wireless telemetry for the doctor to adjust parameters remotely. The first implantable pacemaker was created by Rune Elmqvist in 1958. More than 1 million people in the world currently use a pacemaker, saving lives on every continent.

13. Build a remote control for a PC.

    Answer: You should build a remote control for a PC. Simple solution: use an IR receiver (TSOP1738, 38 kHz) connected to the USB port via Arduino (programmed as an HID keyboard); the remote control can be a generic TV one or assembled with an IR LED + microcontroller. To control media (play, pause, volume), map the IR codes to the keyboard commands. — The IR signals of common remote controls operate at 38 kHz and use protocols such as NEC, Sony SIRC, and RC5. The Arduino Pro Micro and Leonardo have native HID hardware (they emulate a keyboard/mouse via USB). Libraries such as IRremote.h decode and encode signals easily. Total assembly cost: about R$ 30-50, perfectly affordable for a Pathfinder educational project.

14. Build an AC wattmeter for household appliances.

    Answer: Build a simple AC wattmeter: a current sensor (TA12-100 or ACS712) + a voltage sensor (resistive divider) + Arduino + a 16x2 LCD display. It measures V (the mains voltage 127/220V), I (the appliance's current), and calculates P = V × I × cos(φ). Cost R$50-100. Present it by measuring the consumption of a real household appliance (a lamp, an iron) to the instructor. — The ACS712 is a Hall current sensor with a linear analog output, easy to read with an Arduino. For real power (kWh), the Arduino shows the value in watts and can total the consumption. Commercial wattmeters (Kill A Watt, Power Monitor) cost R$100+. Common household appliances: a shower heater 5500W, a microwave 1500W, a refrigerator 100W in use. The cos(φ) factor is decisive in motors (air conditioner, fan).