For the Schmitt trigger oscillator shown in the given figure

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For the Schmitt trigger oscillator shown in the given figure saturation output voltage are + 10 V and – 5 V. The frequency of oscillation is ___________Hz

1. 869
2. 879
3. 889
4. 899

Correct Option: A

Switching voltage are

V₊ =	10	= 5V, V₊ = -	5	= - 2.5 V
	2		2

The charging and discharging of capacitor is shown in the figure

∴ 5 = 10 + (– 2.5 – 10) e^-t₁/RC
⇒ e^-t₁/RC = 2/5 ⇒ t₁ = RC ln 2.5
∴ – 2.5 = – 5 + (5 – (– 5)) e^-t₁/RC
∴ e^-t₁/RC = 1/4
⇒ t₂ = RC ln 4,
T = t₁ + t₂ = RC ln 2.5 + RC ln 4
= RC ln 10 R
= 50 kΩ, C = 0.01 μF
⇒ T = 50k × 0.01μ × ln 10 = 1.15 ms
ƒ = 1/T = 869 Hz