Circuits for Non-Inverting and Inverting
Here is a problem that the Schmitt trigger solves. You have built a circuit to turn on some lights when it gets dark. But when the lights turn on, it gets brighter so the lights go off again. But then it is too dark so they come on again - flashing on and off rapidly.
The Schmitt trigger solves this problem by having different threshold voltages for turning on and off.
When it gets dark, the lights come on. This makes it lighter but not light enough to turn the lights off again. Later when it gets light again, the lights go off. This makes it darker but not dark enough to turn the lights on again.
This behaviour is called hysterisis.
In this diagram, the yellow box is the Schmitt trigger. The 1M resistor provides positive feedback. This changes the threshold voltage where the circuit switches over. It also ensures sudden and complete switch over once the switch over starts. To calculate the threshold voltages, do potential divider calculations.
