Electronics Fundamentals
Use this page to revise the electrical vocabulary you need before you wire a prototype.
Voltage, current, resistance
- Voltage is electric potential difference (volts). Current is charge flow (amperes). Resistance opposes current (ohms).
- Ohm's law: \(V = I R\). Power: \(P = V I\).
- In a series circuit the current is the same; voltages add. In parallel, voltage is the same; currents add.
Passive parts
- Resistors limit current (LED series resistor) and set dividers.
- Capacitors store charge; used for decoupling near an MCU pin.
- Inductors and motors store energy in a magnetic field — switching them without a flyback diode (or a proper driver) spikes voltage.
Logic levels and grounding
- Logic high/low are voltage bands defined in the datasheet (
V_IH,V_IL), not "whatever the USB LED is doing". - Common ground is required for a signal between two boards. Level shifting is required when 5 V and 3.3 V parts share a bus.
Starting Points
- Platt, C. Make: Electronics. Maker Media.
- Electronics & circuit prototyping
Key Points
- You can state Ohm's law and compute a series LED resistor from supply, \(V_f\), and target current.
- You can distinguish series vs. parallel and what stays equal in each.
- You can explain what a decoupling capacitor is for next to an IC.
- You can explain why motors need a driver/diode, not a GPIO pin.
- You can explain logic-level mismatch and why a shared ground matters.