How Is the Frequency of a Sawtooth Wave Oscillator Calculated?

[gsan]

Hi, I need to design a sawtooth wave oscillator, and I found this designe from http://hobby_elec.piclist.com/e_ckt17.htm

does anyone can show me how to get the equation, f=(1/2C(R1+R2))x(R3/R4) and also the osillator is valid for what range of the frequency, thanks.

 

[berkeman]

Whether this is homework or not, you need to show some of your own work before we can provide some tutorial help.

What do you think the circuit is doing, and why? What would the logical components of a sawtooth generator be? Are they in that circuit diagram? How would you go about analyzing the circuit, to try to see if the equation listed is correct? What error terms would you think might also need to be accounted for, in addition to the equation? What limitations would there be on the circuit's operating frequency and un-trimmed accuracy?