Check the listing for details. 10pcs NE555 Pulse Frequency Duty Cycle Adjustable Module Square Wave Signal T. Condition: New, Made in China. Listed at 13.21 USD. 5/10pcs NE555 Pulse Frequency Duty Cycle Adjustable Module Square Wave Signal Generator 5V-12V Stepper Motor Driver ne 555 Is used as a square wave signal generator generates a square wave signal used for experimental development. Input voltage: 5V-15VDC. 5V power supply, the output current can 15MA around; 12V power supply, the output current can 35MA around; The output amplitude: 4.2V V-PP to 11.4V V-PP. (Different depending on the input voltage, the output amplitude will be different) The maximum output current: 15MA (5V power supply, V-PP greater than 50%), 35MA (12V power supply, V-PP greater than 50%) The output with LED indication, there is no output straightforward (low LED volume, high LED off frequency is relatively low, the LED flashes); The output duty cycle can fine-tune, duty.