Practical Tech Guides

Useful steps, clear explanations and official resources. Choose a topic below.

How to use a digital multimeter

Read your meter’s manual and inspect the insulated leads. Put black in COM and red in V/Ω. Leave A/mA sockets unused for these exercises.

How to test an AA alkaline battery

Use a loose, undamaged alkaline AA, nominally 1.5 V. Do not test leaking or hot cells. Black lead in COM; red in V/Ω. Select DC V, autorange or a range above 1.5 V.

Understanding rechargeable AA voltage

Read the chemistry printed on the cell. NiMH AA is nominally 1.2 V, not alkaline’s 1.5 V. Do not assume every rechargeable AA uses the same chemistry.

Testing low-voltage continuity safely

Use only a loose passive wire, switch or resistor, disconnected from every supply and battery. Do not test household wiring or power-supply internals.

Voltage, current and resistance

Voltage (V) is potential difference; current (A) is charge flow; resistance (Ω) opposes that flow. In an ohmic resistor, I = V/R. At 3 V across 1,000 Ω, current is 0.003 A: 3 mA.

Recognizing common USB connectors

USB-A is the broad rectangular plug on many computers. USB-B is the squarer connector often on printers. Micro-B is small and asymmetric on older phones and accessories. USB-C is oval and reversible. Do not force a connector.

Basic SSD and RAM identification

Start with your operating system’s storage and memory information and the manufacturer’s model specifications. You often do not need to open the computer. RAM is temporary working memory; an SSD stores files when powered off.

A beginner battery-powered LED circuit

Use two undamaged AA cells in a 3 V holder, a red LED with a typical forward voltage near 2 V, and a 330 Ω resistor rated at least 0.25 W. Check the LED datasheet; other colours may need a different design.