Op-amp based PWM genarator

Ok so 555 are the comon used in pwm generator but in my country they do not sell them and i wont to have a pwm generator so i just found somthing on the internet that you could use op-amp as pwm generator i found the circuit buld it up but i wouldnt go to that specified frequency that i woned so after some mods i make to it.
Now it goes up to 55khz and down to 10khz so not so bad for me . And the good thing about this one is that it hase audio modulation.

Step 1: Parts

You are going to need these parts


1:Soldering iron
2:Solder
3:Soldering skills(not so much)
4:perfboard
5:Tl072 op-amp
6:Some resistors
2x100k , 2x10k , 1x1k
7:2 Capacitor
1x1nf , 1x470nf(this is for audio modulation)
8:2x 10k Potentiometer

Step 2: Getting evry thing setup

So this circuit dosent have so much component to solder so it is not so hard and probaly you could make this for 15 minutes.You just have to follow that circuit and you should do evry thing good.

Step 3: Finally

                                                   

Finally you should get these reading and it should work ride away if you had your mind on it if not try find what hase gone wrong.If you wont to run something that does require much more than 100ma than you should put a mosfet

Step 4: Projecs

OK i like high votage and of course i had to try the flyback first and i makes so much corona and at 12V make a great spark.You can use this type of circuit in any project form pwm dc moter controller to dc to dc converters