Check the listing for details. NE555 Duty Cycle Pulse Frequency Adjustable Square Wave Generator Module. Condition: New. Listed at 1.25 USD. On-board chip NE555. A single channel output, square wave pulse generator module based on the ubiquitous NE555 timer IC. The module can be powered from a wide power supply range (4.5 to 12V) and will produce a continuous square wave output between 15Hz to 24KHz which can be set by on on-board multi-turn potentiometer. Useful for applications where an approximate frequency clock source is required such as for stepper motor step generation tone generation etc. Specifications: PCB Color: Blue Supply voltage: 4.5 to 12V Supply current: 3mA at 5V Vcc Min freq (approx): 15Hz 49% duty cycle at 5V Vcc Max freq (approx): 24KHz 89.4% duty cycle at 5V Vcc Output voltage: 4.5V at 5Vcc / 11.5V at 12Vcc Size: 29 (mm) x12 (mm) Package included: 1 X NE555 frequency adjustable pulse generator module