# Questions tagged [schmitt-trigger]

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

227 questions
Filter by
Sorted by
Tagged with
53 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 ...
• 23
66 views

### 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. ...
55 views

### 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 ...
69 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 ...
187 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 ...
• 706
79 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 ...
147 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 ...
• 115
147 views

### 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?
64 views

### 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 "...
• 1,052
66 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 ...
• 369
99 views

### 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 ...
92 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 ...
• 41
1 vote
120 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
111 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 ...
• 113
125 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 ...
• 11
349 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. ...
96 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, ...
99 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
112 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 ...
170 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 ...
• 297
131 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 ...
• 121
1 vote
50 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 + ...
• 125
118 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 ...
98 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 ...
• 5
262 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 ...
214 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 ...
115 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 ...
• 21
364 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.
63 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 ...
• 409
31 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 ...
193 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 ...
76 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 ...
92 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 ...
563 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 ...
964 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?
• 33
86 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 ...
81 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?
• 33
404 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 >= ...
• 253
444 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?
• 33
1 vote
117 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 ...
• 11
1 vote
77 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 ...
• 651
1 vote
189 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 ...
1 vote
63 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 ...
• 323
1 vote
174 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 ...
• 11
1 vote
43 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 ...
1 vote
68 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?
1 vote
945 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 ...
• 69
1 vote
405 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 ...
• 113
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\...