Refer to the Schmitt trigger circuit and the following specifications. Given R2 = 80 kΩ, ±Vs = ±11V. Determine the value for R1.

High output voltage level, VoutH = +4.5 V

Low output voltage level, VoutL = -5.0 V

Upper threshold voltage, VUTP = +2.0 V

Lower threshold voltage, VLTP = -2.5 V

Express your answer with two decimal places.

1 answer

To determine the value for R1, we can use the formula for the upper threshold voltage of a Schmitt trigger circuit:

VUTP = VoutL * (R1 / (R1 + R2))

Plugging in the given values:

2.0 V = -5.0 V * (R1 / (R1 + 80 kΩ))

Rearranging the equation to solve for R1:

2.0 V * (R1 + 80 kΩ) = -5.0 V * R1

2.0 V * R1 + 160 kΩ = -5.0 V * R1

7.0 V * R1 = -160 kΩ

R1 = (-160 kΩ) / (7.0 V)

R1 = -22.857 kΩ

Since resistance cannot be negative, we can take the absolute value:

R1 = 22.86 kΩ

Therefore, the value for R1 is 22.86 kΩ.