In the technical literature you find the following description: "A Schmitt trigger circuit is a comparator circuit comprising a positive feedback, so that the switch-on and switch-off threshold do not coincide."
Circuit diagram Schmitt tigger using a comparator. |
Circuit diagram Schmitt tigger using a comparator. (Enlarge) |
In a positive feedback (also called regenerative feedback) the output of the comparator is connected with the input. For this you use the resistor R3.
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Turning the potentiometer P1 you quickly realize that the switch-on and switch-off points no longer coincide! You have added a hysteresis to the voltage comparator. You have again the typical behavior of all Schmitt triggers. However, you want to have a closer look... |
Voltage Profile of a Schmitt trigger. |
