Questions tagged [schmitt-trigger]

Anything related to Schmitt trigger circuits. Schmitt triggers are positive feedback comparator circuits exhibiting hysteresis.

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51 views

Protect circuit Schmitt Trigger

This circuit is a protect circuit, and I search the google it seems like Schmitt Triger circuit,but I don't undertstand why should need the D1, and I don't know what's the function of D1. Can someone ...
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25 views

How to get the full range of output voltage (0-5V) from a differential pair circuit as a schmitt trigger?

The circuit works in the hysteresis range of 2.5V - 1.5V. The output voltage does not reach the full range because I have a dc offset of 1.8V. What's the easiest way to get the full output range with ...
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2answers
117 views

Initial condition of Schmitt Trigger Circuit

I am trying to understand working of the following circuit; It has Input from 0 to 7V and based on the Input value Output A to D will be High or Low but ... Is it Inverting Schmitt Trigger ...
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1answer
61 views

Schmitt trigger inverter not properly outputting 5V

In my project I'm working on right now, I'm trying to use a Schmitt trigger inverter to help debounce input signals. Below is my overall circuit I am trying to implement: The Schmitt trigger inverter ...
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1answer
35 views

Schmitt trigger low threshold calculation

I have this classical Schmitt trigger circuit from an old Elektor magazine. It describes the following, when U1 is lowered (from a high state): If the right transistor cuts off entirely and the left ...
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3answers
511 views

Minimizing signal delay when debouncing

I have a mechanical switch that I'd like to use as a signal source for a digital input of a microcontroller. The switch is normally closed, and I'd like to detect the switch being opened as quickly as ...
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5answers
853 views

Can we declare Schmitt triggers to have memory? Can we call their output levels states? [closed]

Are Schmitt triggers able to be declared as having memory? Can we call their output levels states?
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45 views

Comparator output problem

I have this comparator circuit using an op-amp. This is my actual op-amp used in the circuit. I have used TL072 as I didn't have the simulation model. This circuit is used to trigger the output when ...
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1answer
24 views

Flyback driver using cd 4093

In this circuit can any one tell me complete working of ic cd 4093. Mean how schmitt triggering occur in this circuit? And how to draw square wave in different steps of gates? What is the purpose of ...
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49 views

Why is it necessary to use a voltage limiter at the output port of a Schmitt trigger?

Why is it necessary to use a voltage limiter at the output port of a Schmitt trigger? How are switching thresholds determined in various types of Schmitt triggers?
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2answers
221 views

I need help debouncing a push button

I am trying to debounce a button. Here is my result so far after placing a 1uF ceramic capacitor in parallel with the button: This should work as an input to my Arduino 5V since it has High: U >= ...
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265 views

Why doesn't the following circuit have negative feedback?

Consider: The Sedra book says that it's a Schmitt trigger, so there is positive feedback, but why doesn't it have negative feedback as well?
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46 views

3.3V to 15V PWM converter

I have the good old problem of converting a 3.3V logic voltage to a higher voltage. Higher means everything between 12 and 20V. With 15V being used most of the time. The highest frequency I use now is ...
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1answer
35 views

Maximal resistance in series with input of 74LS14 Schmitt-Trigger-Inverter

I was experimenting with a 74LS14 Hex-Schmitt-Trigger-Inverter (datasheet). I notice that with the input pins are not connected, the output pins are low. Furthermore when I had a 10k resistor in ...
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2answers
93 views

Schmitt trigger not working

I have a circuit like this: I am using a LT1719 for the Schmitt trigger. The Schmitt input signal is intended to be a 6 kHz waveform of 0.6 V pk-pk amplitude. When I test the Schmitt with an ...
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2answers
47 views

Design review for photoresistor-controlled linear regulator

I would appreciate some comments/insights/criticism on my design: I want to turn on/off a linear regulator (MIC5504) based on the light. I have tried just using a resistor and photoresistor voltage ...
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0answers
92 views

Solar-powered 74HC14 LED flasher: oscillators interfere

I am building a "nocturnal solar engine" with two LEDs flashing independently, following the description at the old Solarbotics website. I am essentially rebuilding the same circuit. The ...
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0answers
34 views

How to create timing waveforms for an H-Bridge Inverter

This is my first question on Stack Exchange. I am in the process of simulating a wireless charger coil setup on LTSpice. I have tried a Royer/Baxandall oscillator to provide the necessary sinusoidal ...
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41 views

Schmitt Trigger voltage divider

Could someone please explain to me when and why should we add a voltage divider at the inverting input of a Schmidtt Trigger?
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5answers
331 views

High Frequency Square Wave Generator

I want to generate square wave but there are some challenges. Rise time should be less than 2ns as well as fall time (for 0V to 5V). Duty cycle is not so important it should stay high like 40 ns. I am ...
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2answers
101 views

Hardware debouncing using 74LS14 - inverter input does not drop below 800 mV

I just recently started dabbling with electronics, so probably I just made some beginner's mistake. Here's my problem: I want to debounce a switch in hardware. During my internet research, I found ...
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1answer
87 views

How to use op-amp circuit as a threshold trigger

I recently built the following circuit: In case you can't tell, it has 23 volts on the power rail and VEE is connected to ground. I don't have any feedback on the output. I have a simple voltage ...
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4answers
742 views

Why is this derivation of Schmitt trigger circuit's output signal, incorrect?

This is the reference Schmitt trigger circuit. Using KVL, \$V_x\$ turns out to be \$\frac{R_1}{R_1+R_2}V_o\$. Also, $$V_o = A\left( V_x - V_i\right)$$ $$V_o = A\left( \frac{R_1}{R_1+R_2}V_o - V_i\...
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94 views

Schmitt trigger output waveform coming as sinewave

I am new to Proteus. I tried simulating an easy circuit which was a Schmitt trigger using an op-amp. After simulation, the output waveform was an sinewave instead of rectangular wave. Any idea where I ...
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4answers
232 views

Push button de-bouncing, nothing works. [Please, only answer if you have actually done it (recently or often enough) to know for sure!]

I see a lot of text on the internet and here telling us how to de-bounce a switch, in my case a push button. But I have tried all these circuits and I find that nothing other than a 555 monostable ...
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3answers
125 views

Positive edge detection triggers on negative edge too

I have 74LS170s and 74LS670 register files which have the trouble that they are not edge triggered but like SRAM accept data for the entire duration of the write gate being low. So, I have the ...
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34 views

DC Supply voltage drop in a Schmitt trigger circuit

I developed a Schmitt trigger using IC NE555P. I supplied a Vcc of +6v from a DC source. My input is a sinusoidal wave (peak-peak = 4V). First I set the voltage in DC source (+6v) and when I connect ...
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53 views

Schmitt trigger using NE555P gives wrong output

I am trying to create a Schmitt trigger using NE555P to generate square pulses from some periodically changing signals. I used the following circuit diagram and applied some sinusoidal waves (3.3v). ...
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1answer
68 views

Anyway to reduce pulse trigger time width without using ne555timer [closed]

Is there any other way to reduce the time width of the trigger pulse wave without using 555timer?
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4answers
158 views

Is this input-output relation correct? Schmitt trigger

OK, operational amplifier will want to keep node A at GND level. It will try to set its output so that the condition (inverting input potential = non-inverting input potential) is satisfied all the ...
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0answers
75 views

Is this an elegant approach for a simple, debounced tank level controller?

I am interfacing some industrial (24v) process control equipment to some new projects in the embedded realm of electronics (3.3/5V small signal) and am coming up with some simple solutions for ...
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2answers
186 views

Schmitt trigger offset voltage

I found this circuit which generates an offset voltage to the hystersis (so the threshold voltages are for example not -3V and 3V but -2V and 4V). It would be the same as if you remove R1 and put a ...
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0answers
29 views

Temperature Effect on Schmitt Trigger Threshold Levels

I have found minimal information on the internet, as well as in multiple data sheets I have looked at. I'm designing for a large temperature range of 150°C. I require a fairly consistent voltage ...
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1answer
87 views

Open collector / drain question

I'm trying to to find the best way to force an inverting amplifier to postive saturation with a gate input, but otherwise leave the function of the op-amp intact. I've come up with a few ways to do ...
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1answer
101 views

Op amp as a Schmitt trigger

I am working on a project which needs a Schmitt trigger. I designed it using IC UA741. I am using a single power supply of 9V. I am grounding the V-. Here is my design. The circuit works perfectly ...
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1answer
118 views

schmitt trigger and noise

I know that a Schmitt trigger is used to reduce noise in a circuit, but why does noise need to be reduced. How does noise effect the overall circuit and what benefits do you achieve by reducing noise ...
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2answers
119 views

74HC14 waveform question

I am trying to get more familiar with using a 74HC14, as an experiment I have an ldr set up in a voltage divider configuration and the center tap goes to the input of the 74HC14 input 1. I have all ...
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1answer
57 views

Concept of Hysteresis and Threshold point in Schmitt Trigger

I understand the concept of Schmitt Trigger where there is 2 transition threshold points so that input changing between the hysteresis would not create output transitions . The very first observation ...
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1answer
411 views

74HC14 for debouncing: output is too low with Vcc=3.3V

I'm trying to make a keypad for STM32 MCU using a 74HC14D.653 for debouncing. Datasheet says that it can be fed with 3.3V Vcc so I will not have to make level-shifting between it and MCU. The circuit ...
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1answer
105 views

Calculation of a feedback resistor in an inverting shmitt trigger

This is taken from a frequency counter circuit based on a schmitt trigger comparator . The frequency counter has a noisy immunity threshold of 100mV. How would you calculate the Rfeedback resistor ...
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4answers
134 views

Can't get this schmitt oscillator to work…did I goof somewhere?

Below is my attempt at a schmitt oscillator circuit that uses a 74HC14 and lights up three LEDs in sequence. I built it on some breadboard, but nothing lights up. I'm really at my wits end...can ...
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3answers
76 views

Initial pluse from schmitt trigger switch debouncer

I want to use a momentary, normally open, SPST switch to act as a clock pulse on 16x2 character display. Of course, my switch has some bounce so I was looking at debouncing circuits and I always see ...
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1answer
168 views

Why there is RC filter between optocoupler and schmitt trigger?

I want to use schmitt trigger after optocoupler to have clean signal and connect it to MCU.why there is RC filter between optocoupler and schmitt trigger in many designs? How should i connect ...
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2answers
203 views

Purpose of the Schmitt trigger in this midi circuit

I came across an instructable about using midi with a raspberry pi and I was a bit confused about the first circuit from step 2. What are those Schmitt triggers for and are they really necessary? . ...
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2answers
221 views

Schmitt Trigger Level Translation from Encoder

This is my first time using an encoder as well as a Schmitt trigger. Typically, I would do debouncing in software, but I want a hardware solution for the sake of learning how to do so. The encoder I ...
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1answer
1k views

How to power schmitt trigger in LTspice with negative voltage?

I use CD40106 model in LTspice for schmitt trigger, but the circuit I want to simulate has -5 and 0 V levels, CD40106 only accept positive value for VDD and there is no other param to change the value ...
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3answers
236 views

Generating square wave to be inputted into a MCU

There are signals like below picture inputted to MCU STM32f103: (Offset DC about 800mV, Vmax = 2.4V, f = 66 Hz) I want to change it to a squar wave from 0V to 3.3V being accepted voltage range for my ...
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1answer
105 views

Understanding this comparator circuit

This is what I understand about the circuit: It's not a window comparator exactly as the outputs are not connected together and the inverting inputs are actually connected together. They look like ...
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1answer
129 views

Op-amp circuit hysteresis calculation

Given this circuit, I have to find \$\frac{V_2}{V_1}\$ as well as the magnitude of hysteresis. I don't need a full solution. Any hints to approach this problem would suffice. So far, I know the left ...
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1answer
128 views

Pulse width stretching of the 0 pulse with a constant T [closed]

I have a digital output with varying pulse sizes and I want to design an IC to stretch the 0 output for a constant T+ "0" pulse time (as in attached picture). I have tried using a monostable ...

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