Main chip: N5555. Input: DC 5–15 V. Output amplitude: 4.2 Vpp at 5 V input, up to 11.4 Vpp at 12 V input. Output frequency: four selectable ranges = 1 Hz–50 Hz, 50 Hz–1 kHz, 1 kHz–10 kHz, 10 kHz–200 kHz. Output drive: Maximum output current 15 mA at 5 V supply (V-PP > 50%), and about 35 mA or more at 12 V supply (V-PP > 50%). Pulse timing: The output pulse cycle can be finely adjusted. On-time can be adjusted; frequency changes with the on-time since on-time and frequency are not independently adjustable. Indicator: Output with LED indicator. Low level lights the LED; high level turns it off. At low frequency the LED blinks. Use scenarios: - Generate test signals for microcontroller ADC/DAC and sensor circuits across a wide frequency range. - Demonstrate pulse timing and frequency control in teaching labs, showing how adjusting on-time affects frequency. - Perform bench tests on small loads, timing circuits, and filtering experiments that require controlled amplitude and timing.