Sawtooth wave oscillator
The figure on the left shows the case that the A point is positive voltage.
When the A point is positive voltage, the electric current flows to the capacitor(C) through D1 and R1. When the value of R2 is small compared with R1, the B point falls to the negative voltage at short time.
The A point changes into the negative voltage rapidly when the B point falls to the negative voltage and the positive input terminal of IC1 falls below a few 0 V.
For the positive input terminal of IC1 to fall below 0 V, the condition of R3>R4 is necessary.
The figure on the left shows the case that the A point is negative voltage.
When the A point is negative voltage, the electric current flows from the capacitor(C) through D2 and R2. When R2 is big compared with R1, the B point becomes the positive voltage, doing comparative slow.
The A point changes into the positive voltage rapidly when the B point rises to the positive voltage and the positive input terminal of IC1 exceeds a few 0 V.
For the positive input terminal of IC1 to exceed 0 V, the condition of R3>R4 is necessary.
