Questions tagged [schmitt-trigger]

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

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LTspice to PSIM

I was trying to construct the circuit of UC3843 on PSIM and stumbled across a useful circuit created in LTspice. Now I am confused about these circuit symbols and what they represent: At first glance,...
2 votes
3 answers
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Origin of the signal in an oscillator composed of a Schmitt trigger and an integrator

Following instructions, we built this oscillator as part of our electronics course: I was surprised at first that we could get those signals without any initial signal connected to the op-amps input. ...
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1 answer
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How to generate a clock signal using an op-amp

I am trying to build a circuit which toggles a lamp on and off. I am using a JK flip-flop for the toggling action. I want a clock pulse of 1 Hz. I know there are many ways to generate a clock pulse, ...
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How can I boost the output current of this pulse generator (LF353, supplied with ±15 V) to above 25 mA?

I have a pulse generator design. Everything works fine, but it is required that the output current is above 25 mA. (The 9.69 kΩ is just a variable resistance to modify the output frequency.) ...
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2 votes
3 answers
678 views

Why is my op-amp pulse generator (LF353) delivering way less voltage (±2 V) than the voltage supplies of the amplifier (±15 V)?

I had to design the following circuit as a pulse generator so that if I vary the resistance the frequency will vary as well. It's defined by the frequency expression: $$f=\frac{1}{2R_4C_1\ln(3)}$$ ...
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2 votes
4 answers
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Using a Schmitt trigger IC vs making one from op-amps or transistors

In a professional setting, what is the benefit of using a Schmitt trigger IC as opposed to making one from op-amps or transistors? In a high volume application, wouldn't an op-amp implementation be ...
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8 votes
1 answer
496 views

Does the 74LVC1GU04 actually have "Schmitt-trigger action" on its input?

The 74LVC1GU04 is an unbuffered inverter, which (according to the datasheet) is intended to be used in linear mode in applications, such as crystal oscillators and linear amplifiers with negative ...
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Trouble with FSM circuit using Schmitt trigger clock

I'm having some trouble with my circuit based on the design below, that I built for the lab. I'm using a Schmitt trigger clock. I built the circuit on a breadboard and connected it to the clock and ...
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62 views

Jitter of schmitt trigger oscillator higher than expected

I implemented the following circuit on a pcb board. The goal of the circuit is to measure the capacitance of C1 and C2 in a differential way. C4 and C5 are the guards of C1 and C2. The comparator ...
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1 vote
2 answers
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D-type flip flop and Schmitt trigger [closed]

I've built a D-Type flip flop + Schmitt trigger to convert a momentary switch in a toggle switch using an SN74HC74N Dual D-Type Positive-Edge-Triggered Flip-Flops With Clear and Preset and a CD40106BE ...
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1 answer
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Simulate Schmitt trigger on Simulink

I'm trying to make the simplest circuit to see the Schmitt trigger behaviour on Simulink. I have the following circuit with the Schmitt trigger having the following options : Low level input voltage : ...
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3 answers
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TTL Schmitt trigger vs TTL in relaxation oscillator

as far I know, the schematic works also with a simple TTL NOT gate. Is there any special reason to use the Schmitt Triggers?
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2 answers
248 views

Switching on an SSR on positive voltage and turn it off on negative voltage

I am currently trying to "hack" my way through a door lock, whose PCB cannot be changed. The task is to replace the motor for turning the cylinder with a Solid State Relay. However, the only ...
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1 answer
165 views

Suitable IC for 3.3 V to 5 V level conversion with a Schmitt trigger input [closed]

I've managed to find some ICs which enable level shifting, but none of them have Schmitt trigger inputs. In order to reduce cost and component count, I'd like to ask some of you experienced designers ...
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Square wave RL oscillator

So, I found this nifty oscillator & have been playing with it to generate square waves: https://drive.google.com/file/d/1HfyMNSJ3phSvn3KAczzim-cAPSgw-3Rp/view (Ctrl+S on the text view) As far as ...
2 votes
1 answer
778 views

Schmitt trigger Upper and Lower Threshold voltages

I speak with reference to this (Electrical4u - blog tutorial) and this (All about electronics - video tutorial) on the Schmitt trigger. From what I have understood, in the non-inverting schmitt ...
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How does the CMOS Schmitt trigger work

I have some questions on how the schmitt trigger works. Assuming we start with low Vin hence Vout is high. It means that M1 is ON thus the source of M2 is conducting Vdd hence M2 is On as well. ...
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1 answer
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SPDT switch with opposite polarity and bounce eliminator/debouncer with Schmitt Trigger

I had a question in my electronics course homework pertaining to eliminating the bounce from a SPDT switch with a Schmitt trigger. The switch has two inputs with opposite polarity. I've looked online ...
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111 views

What is the purpose of a negative feedback resistor in a schmitt trigger?

This schmitt trigger is used with an integrator to create a triangle/square wave oscillator but R5 has been added to the typical inverting schmitt trigger topology. I know that in simulation, this ...
4 votes
3 answers
619 views

How to fix oscillation of an 'over-discharge protection' circuit for a lead-acid battery

I've created a circuit to protect my lead-acid battery from over-discharging. I used the following circuit diagram. Over-discharge protection circuit for a lead acid battery: For understandable ...
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210 views

CD4069 toggle switch

How to connect the trigger out instead of the switch? Like a toggle switch. The first trigger out activates the relay and remains ON infinity, the second trigger out deactivates the relay and remains ...
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2 answers
223 views

Schmitt Trigger Circuit Output Rise Time

I'm just working on a basic Schmitt trigger circuit. But I have a question about the rise time of Q3. As shown in figure the collector fall is very sharp, but on the other hand when the transistor ...
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Fan-Out Calculation on LTSpice

I need to find the fan-out of the circuit below. This is a Schmitt Trigger TTL NAND Gate. How can I exactly find the fan-out of the given circuit using LTSpice or calculate it theoretically?
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How to calculate RC values according to threshold points of a Schmitt trigger inverting oscillator [updated]

I'm trying to make a high-period, low duty cycle signal to trigger a regulator (EN pin) for lower power consumption. I tried to simulate this simple circuit in various simulation software, using "...
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2 answers
127 views

Difference between Schmitt trigger IC and IC with Schmitt trigger inputs

This is the second time I am facing this question. First time I thought the second time will never come. My question is what is the difference with the Schmitt trigger IC (for example 74AHC1G14) and ...
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Problem in sensor circuit using a Phototransistor for the Schmitt Trigger circuit

This is my Schmitt Trigger design, which trips at \$2.3V\$ and \$1.7V\$- Here, $$+V_{cc} = 9V$$ $$R1 = 51k \Omega$$ $$R2 = 22k \Omega$$ $$R3 = 330k \Omega$$ \$V_{in}\$ is a square-wave with 0-7V peak ...
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1 answer
137 views

Schmitt trigger input high 3V threshold and input low 0.1V threshhold or other chip?

Are there any chips similar to a Schmitt trigger but with a wider high low input threshold that trigger high with 3-3.3V and low 0.1-0.2V? I need it to alleviate switch bounce. A comment from the ...
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1 vote
3 answers
228 views

Inverting Schmitt trigger design with subtle changes to the hysteresis loop and tripping voltages

Currently, I'm trying to analyze a Schmitt trigger circuit using the 741 IC op-amp, and how it overcomes the problems faced by an open loop comparator circuit. This is a typical positive feedback ...
1 vote
1 answer
273 views

Schmitt Trigger CD40106 has 5V at input with nothing connected

I am using Schmitt Trigger CD40106BE to make an PWM oscillator with controllable duty cycles. The schematic is shown below: However, the LED that should be blinking is constantly on. After some ...
-1 votes
1 answer
220 views

Why is Vout less than Vcc here in a way disproportionate to beta? [closed]

Given: Vcc=9V, duty cycle = 0.5, oscillation frequency=500Hz Note that I am not interested in electronics in any way (I'm planning to continue as a web developer yet need to finish my CCE major) so I ...
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2 answers
870 views

Converting latching switch to momentary output

I'm trying to get a latch switch to send a pulse for around 3 seconds or so. The pulse doesn't need to be pretty or precise. The circuit will be used to sound a buzzer when the switch is flipped on. ...
2 votes
2 answers
134 views

Ideal v. Non-Ideal (?) Schmitt Trigger Transfer Curve

I was doing an assignment about op amps and I had to simulate a Schmitt Trigger and plot its transfer curve. The assignment handout gave me a plot to compare the curve with. Here are both the plots, ...
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154 views

What is the output of the integrator? How do I find the frequency? Op-amp integrator+Schmitt trigger

This is the circuit: Integrator analysis: From this formula I don´t know how to get the frequency. (I don't know if this is right, but I think it is.) I found a website that says the frequency is R3/...
1 vote
1 answer
118 views

BC639 16 exploding on custom design

On a board I designed, a transistor, BC639 16, is exploding. A pinball machine has one board that has some design flaws. Its schematics are these: This PCB has 8 optos (QVE11233.0086) that are ...
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1 answer
406 views

Understanding the Schmitt trigger circuit using CMOS inverters

This is the circuit I'm trying to understand: What I understand: Clearly, whenever \$V_{out}\$ is low \$M_{3}\$ is off and the strength of \$M_{2}\$ and \$M_{4}\$ surpasses that of \$M_{1}\$ so the ...
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1 answer
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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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1 vote
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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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2 answers
224 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 ...
-3 votes
1 answer
132 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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4 votes
2 answers
321 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 ...
4 votes
2 answers
271 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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1 answer
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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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1 answer
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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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1 answer
74 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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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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2 answers
233 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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1 answer
99 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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1 answer
153 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 ...
4 votes
3 answers
616 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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5 answers
1k 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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