Electronics · Digital logic and control / Principles and inquiry
PWM brightness and speed control experiment guide
Vary duty cycle and frequency to compare pulses, mean voltage and load response.
How does it work?
Ideal PWM mean voltage is the duty cycle times the supply voltage.
Key relationship
Vavg = DV · τ y′ + y = u(t)
Try this investigation
- Vary duty cycle and frequency to compare pulses, mean voltage and load response.
- Run and record each of the three baseline presets.
- Compare the changed variable and its result with the baseline records.
Interpreting your results
At 50% duty and 6 V supply, what is the mean voltage when frequency changes from 100 Hz to 500 Hz?
3 V
Assumptions and limitations
LED brightness is approximated as proportional to voltage; motor load torque and starting friction are omitted. Experiment on screen; do not reproduce this with real power supplies, outlets or high voltage.