Intro to Schmitt Triggers

Comparator circuits can be sensitive around the threshold point. If the input signal fluctuates around the threshold point, the output will flicker on and off. To prevent this flickering, hysteresis can be built into the input circuit by using a Schmitt Trigger.
This video describes how Schmitt triggers work when you have a single power supply or a double power supply and shows the effects of using one.
For more videos like this as well as tutorials, online text books and example problems, see the website: www.electronx.ca

[@virt1one]

THANK YOU for demonstrating a single power supply schmitt trigger, I had to look around quite a bit to find your video. everyone with an op amp in their hand tunnel-visions thinking you MUST have a dual power supply if you're using an op amp.

[@mryoureauser6723]

The circuit has a “spillover effect” and the concept has become a mode of operation adopted in many other industries. For instance the fluctuating input voltage can be a patient in a medical setting that “should be ignored” because the volume of the complaint/request/refusal hasn’t met a certain threshold. The differing On/Off voltages can be an appearance time displacement of the care provider and won’t happen correctly at a critical moment. By the time the output coordinator charges out back into the node to inform about the mistake in the delivery location, the medication is delivered to an area much later to the proper placement point. Complacency to discontinue instantaneous intervention.

[@mrengtop]

What a great explanation.. Thank you

[@t1d100]

Super-excellent! Just what I needed; I am learning about DIYing Solar LED lights. Well taught and demonstrated. I am having a little difficulty setting up a Texas Inst. SN74AC14 Schmitt Trigger, because the data sheet does not show an equivalent circuit. So, I am not sure where to add a pot to trim/set the light sensitivity. That means that I will actually have to read the details of the data sheet - lol.

[@t1d100]

I have been reviewing your information to suss out how to configure your wonderful circuit for my purposes. RE: Circuit @ 3:15 1) The photoresistor has another resistor below it. This resistor does not have a value listed. I am using a 5539 LDR. It is rated at 50-100K Ohms in light and 5M Ohms in dark. Please explain what is going on with the inverting (-) input and how to calculate the value for the unrated resistor. What has me confused is that the LDR and the unrated resistor form a light dependent voltage divider and its voltage output is a moving target. 2) I would like to be able to adjust both the high and low trigger voltages. I believe to do this I would a) make Rfb a 200K trimmable VR and tie it to the wiper of a 20K Ohm pot (voltage divider) that would replace R1 and R2. Please confirm and/or correct. Thank you! Sorry for the poor writing; I am tired and a bit confused. EDIT: I will likely use an LM339 Comparator. That should not effect anything, correct? EDIT2: Sorry, for #1, above. Yes, this the LDR and its voltage is what is moving across the trigger points. Doh! The resistor value is determined by the proper calculation for the voltage range desired.

[@imrana1555]

Website not working .. can’t find it on google

[@RAHUL-xy1ds]

3:25 This means the output voltage is at 0. Can you explain how?

[@ElectronXLab]

The output of the op amp is Avol*(Vin+ - Vin-). Avol is very big, so big that we can assume that it is infinite. If Vin+ and Vin- are not exactly equal to each other, the difference between them will be either a positive or a negative value. Maybe a very small positive or negative value, but still not 0. Infinity times a very small positive number will give you +infinity INfinity times a very small negative number will give you -infinity. IN this circuit, the lowest value, the op amp can output is 0V and the highest value is 5V So, if Vin+ is greater than Vin-, the op amp will want to output +infinity, but it can only output 5v and if Vin- is greater than Vin+, the op amp will want to output -infiniity, but it can only output 0V

[@RAHUL-xy1ds]

@@ElectronXLab thank you so much

[@pputter1]

Schmitt trig with op amp

[@ElectronXLab]

yes