Practical/Laboratory Skills and Project Work
Practical/Laboratory Skills and Project Work tests safe bench practice, component identification, breadboard and PCB construction, soldering, measurement technique and project documentation. Questions are often practical scenarios rather than long derivations.
Core concepts
- Component identification: resistor colour bands give value and tolerance; capacitor codes are in picofarads; diode and LED polarity must be checked; transistor pinouts differ by package; ICs are oriented by the notch or dot marking pin 1.
- Breadboard: each row of five holes is connected internally; the centre gap separates the two sides; ICs straddle the gap. Use short leads and a 0.1 µF decoupling capacitor near IC supply pins.
- Soldering: clean and tin the tip, heat the joint and apply solder, avoid cold joints, excess solder and bridges. Use a suitable iron temperature and keep fumes away; unplug before changing tips.
- Measurement: select the correct range and function, observe polarity, connect ammeter in series and voltmeter in parallel, and use continuity mode only with power removed.
- Project work: prepare block and circuit diagrams, justify components, lay out a PCB, test sub-blocks, enclose the circuit, document testing and cost, and maintain originality and safety.
- Troubleshooting: inspect for loose wires and solder bridges, check supply rails, inject a signal, and compare expected voltages with measured values.
Worked example
A resistor has bands brown, black, red and gold. Brown = 1, black = 0, red = ×100, gold = ±5%, so the value is 10 × 100 = 1000 Ω = 1 kΩ with 5% tolerance. A capacitor marked 104 is 10 × 10^4 pF = 100,000 pF = 100 nF = 0.1 µF. An LED’s longer lead is normally the anode.
Traps that cost marks
- Reading a resistor from the tolerance end and reversing the digits.
- Treating capacitor code 104 as 104 pF instead of 100 nF.
- Reversing an electrolytic capacitor or an LED.
- Inserting an IC backwards or ignoring the notch.
- Using an ammeter in parallel, which can blow a fuse or damage the meter.
- Leaving solder bridges between adjacent IC pins or breadboard rows.