amplitude is adjusted to 5 V by selecting suitable values for
C2 and R3. The value of R2 has no effect on either frequency
or amplitude.
We investigated experimentally the maximum and minimum
frequencies that this proposed circuit can reach before
the output signal gets distorted. Fig. 5 shows the triangular
generator output with frequency of 260 Hz, as the minimum
frequency, while Fig. 6 shows the output with frequency of
410 kHz as the maximum frequency.
The dependence of the triangular wave frequency on C1
and R1 is plotted in Figs. 7 and 8, respectively. In both
figures, the calculated values of the frequency using Eq.
(3) are shown, and the comparison shows a good agreement
between the two results. In Fig. 7, R1 is fixed at 280 V and
C1 is varied from 0.01 mF up to 20 mF, and the frequency is
found to vary from 410 kHz down to 260 Hz. This is wider
than the range shown in Fig. 8, where C1 is fixed at 1 mF and
R1 is varied. This result suggests that C1 is the main circuit
element that we can use to control the frequency of the
triangular signal obtained from this circuit.
The sensitivity of the frequency of oscillation (f ) to the
capacitor C1 is defined by [7]: