Schmitt Trigger Equations and Calculator

The following equation and calculator gives values for Schmitt Trigger and an Inverting Schmitt Trigger.

A Schmitt trigger is a A multivibrator that produces uniform-amplitude output pulses from a variable amplitude input signal. This circuit has many applications, one being the conversion of a sine wave into a square wave.

Schmitt trigger circuits are used as signal conditioning to remove noise from signals used in digital circuits, particularly mechanical switch bounce. They are also used in closed loop negative feedback configurations to implement relaxation oscillators, used in function generators and switching power supplies.

 Schmitt Trigger Input Resistor (R1) Ohms Ground Resistor (R2) Ohms Feedback Resistor (R3) Ohms Inverting Input (V-) Volts Supply Voltage (Vcc) Volts Input Voltage High Threshold = V- + ( R1 * (( Vi / R3 ) + ( Vi / R2 ))) Input Voltage High = Volts Input Voltage Low Threshold = V- ( R1 * ((( Vcc - Vi ) / R3 ) - ( Vi / R2 )) Input Voltage Low = Volts Input Voltage Mid = V- * (( R1 + R2 ) / R2) Input Voltage Mid = Volts Inverting Schmitt Trigger Non-Inverting Input Resistor (R1) Ohms Feedback Resistor (R2) Ohms Non-Inverting Input Voltage (V+in) Volts Supply Voltage (Vcc) Volts Inverting Input Voltage High Threshold (V-in) = Vcc - ( ( Vcc-V+in ) x ( R2 /(R2+R1))) Input Voltage High = Volts Inverting Input Voltage Low Threshold (V-in) = V+in x R2 /(R1 + R2) Input Voltage Low = Volts Inverting Input Voltage Mid = V+in * (( R1 + R2 ) / R2) Input Voltage Mid = Volts

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