Questions tagged [hysteresis]

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Output of LM393 won't swing LOW unless it is pulled up with a LED

I built the following circuit using an LM393 as part of a noise gate for audio applications. It's a voltage comparator with hysteresis. I originally connected a 10 kΩ pull-up resistor and then ...
112 views

Schmitt triggers hysteresis symbols

So we're studying Schmitt triggers at university and we got these representations. Searched them on google for more info and got other representations. Now I'm confused. Can anyone help me with some ...
47 views

What is a suitable hysteresis value and averaging period for a residential thermostat?

I've built a microcontroller based thermostat that I am using to control my home HVAC system. The actual programming and physical assembly has been straightforward. I'm using DS18B20 sensors, so I ...
48 views

Solar power pump - Design critique and help

Okay so, I have a design that 'works' on the breadboard. But I feel like it could use some improvement. Here is my current design: simulate this circuit – Schematic created using CircuitLab ...
72 views

Hysterisis - How do you choose a good value for R3?

simulate this circuit – Schematic created using CircuitLab Above is the basic schematic for a comparator with hysteresis. Determining the values of R1 and R2 is fairly straight forward. They ...
251 views

What is the common name for this seal-in relay?

I'm trying to build a hysteresis water pump system with 2 water level switches. Please see the diagram and explanation of this setup I've taken off the web: The first switch (L) is set at the minimum ...
73 views

Questions regarding eliminating hysteresis in ac dimmer

In the following circuit it says: “This hysteresis effect can be eliminated however, using the circuit from a detailed application note from Littelfuse shown in Fig. 6.4.4. Here the capacitor C1 is ...
171 views

Calculating resistor values for a Schmitt Trigger and LDR circuit

I am trying to make a light sensing circuit which has hysteresis. I want an op-amp (LM358) to output logic 1 (12v) when the light level rises above 250 lux, and output logic 0 (0v) when the light ...
66 views

Magnetic material demagnetization through Curie temperature

It is known that some materials lose their permanent magnetic properties when they are heated above certain temperature known as Curie temperature or Curie point. As those materials are cooled down to ...
225 views

Schmitt Trigger hysteresis

I am studying comparators and Schmitt triggers. And I did not find anywhere how to choose the value of hysteresis. I understand its purpose and I know how to calculate it. But what value is needed for ...
179 views

How can I modify this circuit for some hysteresis and better design?

I need to make a circuit even when the push button pushed and released very fast, the final output will stay ON at 12V for roughly a second. %10 accuracy for the timing is fine. An LED will indicate ...
46 views

-Ve feedback comparator and its threshold values?

I was trying to analyse and understand the following circuit. My intention was to calculate the hysteresis of the comparator. Circuit working: For both compartor input, there will be voltage inputs ...
24 views

Picking Supervisors for a battery with correct Hysteresis

I am trying to find a Supervisors ic that will detect low voltage(5V) on 6v lead acid battery so I can disconnect the battery from the circuit using MOSFET or load driver. how do you calculate ...
618 views

Magnetic field strength and flux density from hysteresis curve

I am trying to measure the magnetic hysteresis curve of a toroidal nanocrystalline ferromagnetic transformer core made of Nanoperm (datasheet linked) using the following circuit. Each of the windings ...
107 views

Analytically obtaining the hysteresis of an opamp Schmitt trigger with RC network in its inverting input

This is a follow-up from here. I have got the following Schmitt trigger circuit implemented already on a breadboard. As seen, the input signal at the non-inverting and inverting terminals of the op ...
228 views

Comparing two variable voltages with hysteresis

All of the designs I have seen for adding hysteresis to a comparator (Schmitt triggers) assume that one of the two inputs to the comparator is set at a fixed reference voltage (typically with a ...
45 views

Op-amp driving mosfet changes hystheresis thresholds?

I have a non inverting push-pull output op-amp with additional hysteresis (Maxim MAX9015) that should drive an N-Mosfet. I calculated the resistor values for the op-amp(R5, R6, R7) for an older ...
312 views

Feedback capacitor in comparator circuit with an OP-AMP

Greetings, This is a scheme of a comparator with dynamic hysteresis. Green line is the output Red line is the input Blue line is the positive feedback. I want to ask for the explanation why C1 does ...
666 views

Calculating Slew Rate from a time-constant

I have to choose an OP-AMP mainly based on slew rate. I am using the op-amp as a differential comparator with dynamic (time) hysteresis with a time-constant 3*tau=500µs. My upper threshold of the ...
242 views

How to add voltage thresholds with hysteresis to the input of a voltage regulator?

Device to be used in: solar-powered microcontroller with some peripherals attached. Meant to operate whenever sufficient power is supplied (light is bright enough for a while). No battery, weather ...
659 views

How to design a comparator using op-amp?

Intention is to design a comparator with following specification: Input: 0V to 1.65V, Output: Low Input: 2.1V to 5V, Output: High This is the TI design doc I have refereed for the design. Please ...
147 views

Comparator hystereris

Can someone help me to understand a little better how the hysteresis work in this circuit? I can understand the explanation below why VTRP- = vgs2-vgs1 = .... Also, I didn't find the meaning of the ...
81 views

Comparator circuit undesirable fluctuations

I have designed a comparator with hysteresis and rail to rail operation and my output depicted in figure1.The inputs of the comparator is a sine wave signal and a triangular waveform as shown below....
958 views

Why does hysteretic current-mode control have variable switching frequency?

This figure below is from Raymond B. Ridley Dissertation "A New Small-Signal Model for Current-Mode Control". Here is an except from the document: The general implementation of hysteretic current-...
60 views

Can I make a peak voltage indicator with a small number of components?

I have a switchmode power supply that rectifies the main voltage with a full bridge rectifier and smoothes it with electrolytic capacitors. Assuming a 115 volt AC power supply, this gives a peak ...
393 views

How can I calculate the hysteresis of Reed sensor?

As question says, I want to calculate the hysteresis of Reed sensor and I don't know how. As I seen in Reed sensor's documentation, hysteresis may be x/y, or the difference between x and y, and I'm ...
144 views

Is this AN on comparator with hysteresis wrong?

Reading this datasheet of the LM94022, chapter 8.3, where is shown the following example: I don't know how they get the formulas. I more agree to achieve something like this: taken from this answer. ...
359 views

How to calculate hysteresis when the OPAMP supply voltage is changing

I have designed a GSM/GPS based tracker which is installed at my bike. But it is draining battery too quickly. So, I want to add a cutoff circuit when the bike is not running(battery not charging) ...
86 views

Transformer Hysterisis

I have the following circuit to plot X-Y plot in an Oscilloscope to get Hysteresis curve. R2 and C2 are kept so that the cutoff frequency of low pass filter formed is less than 2Hz. ...
716 views

Open-collector comparator with hysteresis and LED indicator at output

I am trying to choose the correct resistor values to make Vout go high when Vbatt falls below 18V and go low when Vbatt rises above 20V. I've built the actual circuit and my measured values are 18.0V ...
119 views

What causes the uncertainty in the threshold voltage of a CMOS switch?

CMOS switches such as the DG419 have a threshold voltage - i.e. the voltage at which the output state is flipped - which is dependent upon the logic level and the positive supply rail. However, the ...
447 views

Glitch vs runt pulse due to hysteresis

This is a conceptual question. What I understand is that runt pulse is like a glitch but its amplitude is less than the main pulse's amplitude. If Im not wrong on this definition, below illustartes ...
1k views

Stable output from a potentiometer [closed]

A recurring problem with analogue potentiometers is to get a stable output that only changes when the pot is actually moved (i.e. it doesn't output a lot of extremely similar values due to noise or ...
1k views

Adding hysteresis to a window comparator

I have designed a window comparator and am finding it seemingly impossible to add hysteresis. Below is the basic circuit before attempting to add hysteresis. Now I add a feedback resistor to the ...
3k views

Hysteresis in CMOS Schmitt Trigger

! How does this circuit work? why do you get different threshold voltages for increasing and decreasing Vin?
445 views

A question on adding noise and low-pass filer in Ltspice

I’m planning to implement the following Schmitt-trigger circuit: (left-click to enlarge) I made some updates with the great suggestions of jonk in my previous question:Some questions on optimizing a ...
4k views

Schmitt Trigger Comparator 0 - 5V

I have designed a schmitt trigger circuit using an op-amp where the output switches from 0 - 5V based off an input hysteresis from 2.2 to 2.8V. My circuit correctly switches at the correct voltages ...
516 views

Debouncing and hysteresis questions about a Schmitt trigger circuit

Above is a switching sensor which outputs ON OFF pulses by the 33k pull-down resistor. V2 and R_SW models the switching. The sensor output is needed to be measured between 1Hz upto 150Hz. I'm planning ...
138 views

USB-UART FTDI chip VIH

I am working with an FTDI "FT232R" IC [USB to UART conversion], and struggling to understand what the VIH spec of the IC is. I can only find reference to an 'Input switching threshold (VIN)' spec in ...
491 views

Can a MOSFET be on if there is no current flowing through it?

I am reading about hysteresis comparator here and wondering if a MOSFET can be on if $V_{gs}$ is larger than threshold voltage but there is no current flow through it ($V_{ds}$ is zero), As you ...
2k views

Hysteresis calculation for “open-collector output comparator” with a pull-up resistor

Standard comparators such as LM2903 and LM311 have open collector outputs. I see many times the output of these comparators are tied to Vcc by a pull-up resistor (e.g. in a Schmitt trigger case). ...
786 views

Hysteresis in a MOSFET's I-V

I've skimmed through several sparse articles online about hysteresis in a MOSFET's I-V characteristics. What I found was sparse, but some articles attribute uneven-ness in the gate structure, causing ...
199 views

battery overdischage oscillation protection

I previously asked asked an advice on power control of battery operated system. The problem was to cutoff the battery when low to avoid overdisharge. I have built the device according to Olin Lathrop'...
3k views

Can anyone explain why a B-H curve with Hysteresis doesn't result in a highly non-linear input-output transfer function for a transformer?

See the attached picture of a typical hysteresis loop, it is clearly highly non-linear even if you keep the signal small enough to stay out of the saturation region (beyond points b,e). So my question ...
155 views

What does E/A mean?

I'm trying to understand how does UCC28703 PWM-controller work. But I don't understand what do the following pictures mean: and . I know they are comparators, but I don't know what does E/A mean ...
858 views

Intuitive explanation for this hysteresis circuit?

simulate this circuit – Schematic created using CircuitLab I am trying to get an intuitive understanding of this small circuit. I have both breadboarded it to look at behavior on a scope and ...
195 views

ICL 7673 circuit Hysteresis Resistor values

I'm using the ICL 7673 circuit from datasheet "without external PNP transistors". Please help with deciding Rf and Rs resistor values for 0.5V hysteresis. Any help is much appreciated. Please see ...
627 views

How to derive the node voltage for this comparator with hysteresis?

I have the following circuit. U26 is a simple unity buffer and U15 is just a dual comparator. I want the top comparator to compare the battery voltage (VBAT/2) on the inverting input with 2.0V ...