Schmitt Trigger Simulation

Examine the circuit of figure below

Description: schmitt trigger

A note on the Schmitt Trigger

You will notice that unlike all other amplifier circuits you have met so far, this amplifier has the feedback network connected to the non-inverting input.

Electrical Assignment Help Order Now

Suppose the output of the amplifier is saturated high with an output voltage of Vh, then the non-inverting input will see a voltage of Vh*(R2/(R1+R2). When the signal on the inverting-input exceeds this voltage the output will swing to its saturated low value of -VL which in turn sets up a new voltage on the non-inverting input of :

-VL*(R2/(R1+R2)). The output will remain low until the signal on the inverting-input reaches (and goes lower than) this new voltage when the output will swing back high once more.

We therefore have a system involving two threshold levels of Va=Vh*(R2/(R1+R2)) and Vb= -VL*(R2/(R1+R2)).

This gives rise to hysterisis (i.e. the signal has to move a distance of Va - Vb) to change the state of the output. It is this hysterisis behaviour that is called a Schmitt trigger. A device with this characteristic is useful to eliminate the effect of noise on a signal. A signal can suffer noise degradation with unwanted swings up to Va above zero and Vb below zero without affecting the switching function.

Try simulating the circuit of figure 2 where R2 = 4.7k and R1 = 10k and apply a sine generator to the input of frequency 1kHz and amplitude 8V.

Examine V out high and V out low from the Op Amp and evaluate the switching points Va and Vb. Do they comply with the expected values?

Assignment Help | Physics Assignment Help | Physics Homework Help | Physics Project Help | Online Tutoring | Sample Homework

Improve Your Grades with Custom Writing Help
Homework Help
Writing Help
Editing Services
Plagiarism check
Proofreading services
Research Project help
Custom writing services
E learning blogs

Disclaimer : The study tools and academic assistance/guidance through online tutoring sessions provided by AssignmentHelp.Net is to help and enable students to compete academically. The website does not provide ghostwriting services and has ZERO TOLERANCE towards misuse of the services. In case any user is found misusing our services, the user's account will be immediately terminated.