Questions tagged [schmitt-trigger]

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

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1answer
72 views

Design a triangular wave generator using a sinusoidal input

I've been going through online assignments regarding circuit designs. I've gotten a bit stuck on this one: Using a sinusoidal input voltage of amplitude 5 V and frequency 100 Hz, I need a triangular ...
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0answers
48 views

Do I need a separate capacitor bypass for 74xx14 Schmitt Trigger sharing power with Op Amp? [duplicate]

Do I need a separate capacitor bypass (network) for 74xx14 Schmitt Trigger sharing power with Op Amp? Power supply is 500mA but entire circuit is using around 70-80mA. And sub-circuit with OP AMP + ...
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2answers
42 views

Control multiple Schmitt Trigger oscillators from a single current sink

I'm playing with an idea for a VCO (Voltage Controlled Oscillator), and would like to make something a bit out of the ordinary. My idea is to run multiple sawtooth oscillators from a single control ...
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1answer
60 views

Schmitt trigger VS transistor [closed]

Can you please explain for me what is the difference between Schmitt trigger and transistor, especially in driving LEDs and in current consumption. EDIT: There's answers and comments which seem to be ...
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2answers
173 views

In an astable multivibrator, why doesn't negative feedback prevent the output from ever saturating?

What I understand of an astable multivibrator so far is this: The output saturates to one of two extremes, which drives the capacitor in the negative feedback loop to either charge or discharge. Once ...
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2answers
122 views

I am facing a problem while designing a Schmitt trigger circuit

I am applying a Schmitt-trigger to the waveform given in the figure below. . This is a 3.5 volt signal and I want to perform thresholding so I use 1.58 volts as upper threshold and 1.17 volts as lower ...
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1answer
60 views

RC circuit and HEX SCHMITT-TRIGGER INVERTERS

I have a complex circuit, and I am dealing with a problem that appears. I have a RC circuit followed by a 7414 Trigger inverter. My input voltage is 90mV and after the simulation the output looks like ...
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1answer
51 views

using Schmitt trigger to debounce a switch [closed]

How can a Schmitt trigger be used to debounce a switch? please try to explain it with pictures as well.
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1answer
53 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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0answers
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
131 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
62 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
44 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
525 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
889 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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0answers
48 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
36 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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0answers
54 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
272 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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3answers
300 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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0answers
62 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
41 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
115 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
48 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
98 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
36 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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0answers
44 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
481 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
155 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
131 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
819 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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0answers
99 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
290 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
169 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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0answers
44 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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0answers
55 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
70 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
225 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
79 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
284 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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1answer
89 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
109 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
168 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
130 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
70 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
603 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
159 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
141 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
84 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
217 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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