BJT Schmitt Trigger Simulator
Design and analyze a discrete BJT-based Schmitt Trigger. Observe the UTP, LTP, and hysteresis effect on the output waveform.
Schmitt Trigger Circuit Diagram
Note: A speed-up capacitor can be placed in parallel with R1 to improve switching time (not simulated).
Circuit Parameters
Input Signal (Sine Wave)
Design Goals
Enter desired trigger points, then click Auto-Configure.
How It Works & Formulas
The Schmitt Trigger uses positive feedback via the shared emitter resistor (Re) to create two distinct switching thresholds (hysteresis).
Upper Trigger Point (UTP): The input voltage required to turn Q1 ON when Q2 is already ON.
UTP ≈ Vcc * R2 / (R1 + R2)
Lower Trigger Point (LTP): The input voltage required to turn Q2 back ON when Q1 is already ON. The calculation is more complex due to the feedback loop.
LTP ≈ (Vb2_q1_on * (Re + Rc1)) / Re
Calculated Trigger Points & Output Levels
Upper Trigger (UTP):
Vout (High):
Lower Trigger (LTP):
Vout (Low):
Hysteresis (V_H):