Hello I would like to realise an oscillator that generates a CK signal with a frequency of 1kHz and Duty Cycle 30%, I can use a NE555. Because I wanted to realise it as a stable vibrator, but among the specifications I read CheDuty cycle = tH / period > 50%

 

 

The method in post #2 for obtaining a duty cycle <50% is the text-book way of doing it. There is at least one other method, which a bit of Googling on your part should reveal.

 

another alternative was that I could use was the 74HC04 chip
but it seems simpler to me to use NE555 with some modifications

 

You could, of course, also design a 555 astable with a 70% (high) duty-cycle, and then invert that with a transistor to get a 30% duty-cycle.

 

What are your limits of error? How close to 1kHz does it need to be? How close to 30% duty cycle?
You would have to pay a lot of money for the capacitor if you want ±1%. it would be cheaper to use a crystal oscillator and divide it down.
However, if ±10% is good enough, then the 555 will do the job.

 

Crut’s suggestion should be the easiest to implement.

 

 

 

Now I try to do the simulation with a duty cycle of 70% and then use an inverting, after having created an oscillator that generates a CK signal with a frequency of 1kHz and Duty Cycle 30% I have to proceed with a circuit that for each rising edge of the signal CK output from the oscillator generates a negative pulse (1) with duration Tw1=25µs after a delay time TEL=125µs.
To create this circuit I had thought of first using a capacitance obtaining a delay time equal to 125µs and then using the OR, I sized the resistance and the capacitance in such a way as to have a pulse duration equal to 25µs
Do you think this could be a good idea?

 

What are your limits of error? How close to 1kHz does it need to be? How close to 30% duty cycle?
You would have to pay a lot of money for the capacitor if you want ±1%. it would be cheaper to use a crystal oscillator and divide it down.
However, if ±10% is good enough, then the 555 will do the job.

Ho una tolleranza +/- 5% sulla frequenza di oscillazione e sulla durata degli impulsi.


Mod translate, please use English text.
I have a +/- 5% tolerance on the oscillation frequency and pulse duration.

 

View attachment 313870

That will work, but it would work (and the duty cycle would be more accurate) without A1, A2,R1 and C5.

 

Now I try to do the simulation with a duty cycle of 70% and then use an inverting, after having created an oscillator that generates a CK signal with a frequency of 1kHz and Duty Cycle 30% I have to proceed with a circuit that for each rising edge of the signal CK output from the oscillator generates a negative pulse (1) with duration Tw1=25µs after a delay time TEL=125µs.
To create this circuit I had thought of first using a capacitance obtaining a delay time equal to 125µs and then using the OR, I sized the resistance and the capacitance in such a way as to have a pulse duration equal to 25µs
Do you think this could be a good idea?

The accuracy of the threshold voltage on a logic gate is not good. You would not achieve your 5% accuracy.

 

Ho una tolleranza +/- 5% sulla frequenza di oscillazione e sulla durata degli impulsi.


Mod translate, please use English text.
I have a +/- 5% tolerance on the oscillation frequency and pulse duration.

The tolerance on the threshold voltages of a 555 is ±6%, even with 1% tolerance capacitors and resistors you would not achieve your target without a preset to adjust the tiMing.

 

That will work, but it would work (and the duty cycle would be more accurate) without A1, A2,R1 and C5.

I imagine but after realizing a negative pulse lasting 25µs then I need the second circuit

 

The tolerance on the threshold voltages of a 555 is ±6%, even with 1% tolerance capacitors and resistors you would not achieve your target without a preset to adjust the tiMing.

so you recommend adding a trimmer (adjustable potentiometer) to your setup. This allows you to manually calibrate the frequency and duty cycle. You can use a trimmer to adjust the resistance in the circuit to get the specifications you want?

 

I have to create an oscillator that generates a CK signal with a frequency of 1kHz and Duty Cycle 30% and a circuit that for each rising edge of the CK signal output from the oscillator generates a negative pulse (1) of duration
Tw1=25μs after a delay time TEL=125μs. Assume a tolerance of +/- 5% on the oscillation frequency and pulse duration.
to obtain a timed delay of 125µs I thought of using a monostable 555, but it seems too expensive to me, I wanted to use something simpler

 

 

 

have to create an oscillator that generates a CK signal with a frequency of 1kHz and Duty Cycle 30% and a circuit that for each rising edge of the CK signal output from the oscillator generates a negative pulse (1) of duration
Tw1=25μs after a delay time TEL=125μs. Assume a tolerance of +/- 5% on the oscillation frequency and pulse duration.
to obtain a timed delay of 125µs

Don't understand why you need a 30% duty-cycle of a 1kHz signal if you are generating such short pulses.
What does the duty-cycle have to do with anything?