pulse generator

I built a simple pulse generator with a 4MHz crystal and a 4060 counter, to get several output frequencies. I checked them in my scope, and I get quite good pulses, with less than 200ns rise and fall times.

But there're other ways to do it, without crystals.

**broken link removed**

or

**broken link removed**

Do they have any advantage?
Maybe you can change frequency more easily with a potenciometer, while the crystals only lets you some power of 2 divided frequencies. But the crystal is more accurate, isn't it?

Thank you

Yes, the crystal is FAR more accurate. The best solution though is a PLL using a crystal as the reference, so you can switch frequencies easily and accurately.

The simple oscillators have a different frequency with each IC and the frequency changes when the supply voltage changes.

The links I posted, show 2 approaches with IC that do not depend on supply voltage, only R and C.

Yes, PLL is good, but seem much more complex.

patroclus said:

The links I posted, show 2 approaches with IC that do not depend on supply voltage, only R and C.

Click to expand...

No.
The links (performance) show a big change in frequency when the supply voltage is changed.
The datasheets for the ICs show that each one is very different (threshold voltage) which affects the frequency.

patroclus said:

Yes, PLL is good, but seem much more complex.

Click to expand...

Yes, much more complex, but much more useful as well!.