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Schmitt Trigger Equations and Calculator

Instrumentation and Electrical Design

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
Schmitt Trigger      
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)
  Inverting Schmitt Trigger    
Input Voltage Mid = Volts


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