Pulse wave generator with adjustable duty cycle

The circuit of this pulse wave generator is shown in the figure below.

Working principle:

1. The trigger D1 forms an oscillation circuit. When IQ is 1, it charges C2 through R2, causing ICP to be triggered, resulting in IQ being 1; when IQ is J, it charges CI through R1, causing lR to be 1, resulting in J.

Second, the trigger D2 forms a monostable trigger. Every time a pulse rises, 2Q turns off. After 2Q becomes high, it charges C3 through R3, thereby resetting the trigger D2. When the resistance value of R3 is adjusted, the time that 2Q is high can be changed, thereby changing the duty cycle of the emitted pulse.

Things to note during production:

First, the output pulse frequency of trigger D2 is equal to the oscillation frequency of trigger D1.

2. The maximum values ​​of R1, R2, R3, CI, C2 and C3 should be selected so that:

100R,Ci<R2c:=＆c, so when adjusting R3, the duty cycle of the output slope can be changed from 1% to 99%.

3. To improve the output waveform performance, the capacity of C1, C2, and C3 should be as small as possible, or the waveform can be output from 2Q. 4. CD4013 can be replaced by MC14013, HD14013, TC4013, etc.