Check the possible voltages at Q3 collector: When Q3 is off, it is obviously close to the supply voltage. These are classified into two types namely inverting Schmitt trigger and non inverting Schmitt trigger.The inverting Schmitt trigger can be defined as an element of output is connected to the positive terminal of the operational amplifier.Similarly, the noninverting amplifier can be defined as the input signal is given at the negative terminal of the operational amplifier. They are simple in operation (as simple as can be) and each one does one specific task. The other point thats not covered by the online calculator is the 'load' that the comparator output is driving into, when using an open output comp like the LM393. Version 1A and 1B are basically the same design, except that one uses 2 NPN and the other uses NPN and PNP. Any type of input voltage can be converted into its corresponding square signal wave. circuit simulator applet falstad. In the following circuit, a transistor is driven by a sinusoidal voltage source through a Schmitt Trigger. It is an active circuit which converts an analog input signal to a digital output signal. The two-transistor Schmitt trigger and how it works. That wasnt clear right off. The transistor in the two examples above, can be replaced with a Power MOSFET device or Darlington transistor if the load current is high. Joined Jun 17, 2014 7,872. to +5-volts. In BJT version it works because we have Ic1