This module scope:

1. as a square wave signal generator generates square wave signals, for experimental use.
2. for generating a driving stepping motor driver of the square wave signal.
3. generation of tunable pulse for MCU to use.
4. generation of tunable pulse, control circuit.

1. the main chip: NE555;
2. he input voltage:5V-15VDC. 5V power supply, the output current can be controlled in 15MA;12V power supply, the output current can be controlled in 35MA;
3. the input current is greater than or equal to 100MA:
4. the amplitude of the output:4.2V V-PP to11.4V V-PP. ( according to different input voltage, output amplitude will be different )
5. the maximum output current: = 15MA (5V power supply, V-PP > 50% ),35MA (12V power supply, V-PP greater than 50% )

 advantages:

1. the output with LED indication, there is no output straightforward ( low LED lights, high LED, low frequency LED flashing);
2. the output frequency range of grades are optional, so that the output frequency of a continuously adjustable;
3. LF :1Hz ~ 50Hz
4. MF :50Hz ~ 1kHz
5. MHF:1KHz ~ 10kHz
6. HF:10kHz ~ 500kHz 
7. the output duty ratio can fine tune;
8. adjustable output frequency;

       period T = 0.7( RA+2RB ) C

       RA, RB for 0-10K adjustable;

       LF of C      =0.001UF;

       MF of C     =0.1UF;

       MHF of C  = 1UF;

       HF of C     =100UF

       so buyers can calculate the frequency of the waveform