Electrical Basics

Use a short Ohm's law refresher to predict voltage and current in simple series and parallel resistor circuits.

Translate a simple circuit schematic into breadboard connections, accounting for connected rows and potentially split power rails.

Select an LED's current-limiting resistor from supply voltage, LED forward voltage, target current, and resistor power rating.

Build a switched, battery-powered LED circuit with correct polarity and a power-off check for short circuits.

Use the ANENG AN8009 to check continuity and resistance only on disconnected, discharged low-voltage circuits.

Measure DC voltage across components in a battery- or USB-powered circuit using the AN8009's appropriate mode and lead sockets; do not measure household mains.

Measure current in a small battery-powered LED circuit using a suitable fused meter input in series, restoring the leads to the voltage-measurement sockets afterward.

Locate an open connection, unintended short, or reversed LED in a low-voltage circuit using a schematic and targeted measurements.

Build a potentiometer voltage divider and verify its adjustable output with a multimeter.

Choose a fixed resistor for an LDR voltage divider that produces a useful voltage change over the intended light range.

Verify diode orientation and forward conduction using the multimeter's diode-test mode on an isolated component.

Demonstrate capacitor charging and discharging in a low-voltage RC circuit while observing polarity, voltage ratings, and safe discharge precautions.

Select a base resistor for a small NPN transistor used as a saturated low-side switch, checking load current and component ratings.

Build a 2N2222 or BC547 low-side switch for a current-limited LED load using the actual transistor's verified pinout.

Check a proposed Uno R3 circuit against its pinout, permitted signal voltages, and per-pin and aggregate current limits, distinguishing USB, VIN, and regulated power pins.

Configure the Arduino IDE for the Uno R3 CH340 clone and upload the built-in Blink example, resolving board, port, cable, or driver issues if needed.

Adapt familiar Java or JavaScript numeric expressions to AVR Arduino C++, accounting for setup()/loop(), 16-bit int values, integer division, and explicit conversions in a small electrical calculation.

Use the Serial Monitor to inspect changing program values and distinguish an incorrect computation from a wiring problem.

Control an external current-limited LED with an Arduino digital output.

Read an active-low pushbutton using INPUT_PULLUP without leaving the input floating.

Schedule an LED task without delay() using wrap-safe unsigned subtraction with millis().

Implement software button debouncing that produces one event per deliberate press.

Convert the Uno's 10-bit analog reading from a potentiometer into an estimated voltage using the measured reference voltage.

Control LED brightness with PWM and distinguish duty cycle from a true adjustable DC voltage.

Implement an LDR-controlled night-light using measured light levels and separate on/off thresholds to prevent flickering.

Convert LM35 sensor readings into temperature using its verified pinout, voltage-to-temperature relationship, and the Uno's ADC reference.

Install a compatible DHT11 library and obtain temperature and humidity readings while respecting its sampling interval and detecting invalid results.

Wire the I2C LCD backpack to the Uno and discover its address with an I2C scanner after verifying its supply and pin labels.

Display changing sensor readings on the 16-by-2 I2C LCD without repeatedly clearing the entire display.

Determine whether a kit buzzer is active or passive and select a drive circuit that respects its voltage and current requirements, using a transistor when necessary.

Produce a timed audible alert without blocking other tasks, using tone() for a passive piezo buzzer or switched drive for an active buzzer as appropriate.

Produce a schematic and power budget for a USB-powered Uno monitor using an LDR, either the LM35 or DHT11, the I2C LCD, a pushbutton, and a suitably driven buzzer.

Assemble the monitor from its schematic and complete polarity, continuity, and supply checks before enabling USB power.

Integrate scheduled sensor acquisition and LCD updates into one nonblocking loop that continues handling user input.

Implement a debounced pushbutton interface that switches between current sensor readings and configured alarm thresholds.

Implement NORMAL, ALARM, and SENSOR_FAULT states with explicit transition rules, hysteresis where appropriate, and safe handling of invalid readings.

Validate the monitor with a test table covering threshold transitions, sensor faults, rapid button presses, and power cycling, using serial output and low-voltage measurements to diagnose failures.