NE555 based pulse generator with LED status indicator - Main chip: NE555. Input voltage: 5V-15V DC. - LED indicator shows output activity: LED on when the output is low, LED off when the output is high, and the LED will blink at low frequencies. - Output frequency ranges for smooth continuous adjustment: - Low: 1 Hz to 50 Hz - Medium: 50 Hz to 1 kHz - Medium-high: 1 kHz to 10 kHz - High: 10 kHz to 200 kHz - Duty cycle: finely tunable. Note that duty cycle and frequency are not independently adjustable; adjusting the duty cycle will change the frequency. - Benefits: simple, standard NE555 timing source compatible with common 5-15 V DC supplies; easy to verify operation via the LED indicator; wide frequency coverage from 1 Hz to 200 kHz in selectable ranges. - Practical applications: - Generate timing signals for microcontrollers and digital logic testing - Lab experiments and RC timing/oscillator studies - LED flasher or signaling indicator projects