555 adjust frequency simultaniously with dyty cycle

[Amalinda]

i want to create a timer circuit that has two potentiometers ; one for frequency and the other for duty cycle. The problem i have faced using 555 times is that when i change R1,R2 to change duty cycle the frequncy changes and vice versa... Now i think if this is even possible using a 555.

How about an op amp design?
any one who can help me?
I want to set to a frequency value and then change duty0cycle afterwards and do the viceversa too..
is this possible?
how about using the control-pin?
thanks in advance.

 

[Tahmid]

Use this circuit:

RV2 and RV3 set the frequency. RV1 sets the duty cycle. Adjust the value of the components as you feel necessary.

Hope this helps.
Tahmid.

 

[tpetar]

555 Timer - Frequency and Duty Cycle Calculator
http://www.bowdenshobbycircuits.info/555.htm

555 Calculator
http://www.royalrife.com/555_calculator.html

 

[Amalinda]

thank you so much Tahmid .
Greatly helpful.

One more question. Now your circuit makes sure ONE frequency is provided at all times no matter what the position of the Variable resister it.
great!, because we can easilly change the duty cycle without effecting the frequency.
Can we use the pin 5, fix a variable resister and change the voltage at PIN 5 and expect frequency to change with NO EFFECT on duty cycle?