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Questions tagged [comparator]

A comparator compares two voltages or currents and switches an output to indicate which is larger.

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1answer
243 views

Arduino inductance meter using op-amp as comparator?

I want to create an Inductance meter with an arduino nano, for that I follow that link whose theory convinced me : tutorial (The Diode on schematic remove analog negative voltage, Edit: I have ...
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1answer
75 views

Why does this LTC1440 Comparator switch so slowly?

I am trying to build an undervoltage protector for a 6S LIPO battery. My idea was to use a comparator to switch off an NMOSFET when the battery fell below a preset voltage, 20V: R20, R21 and C20 ...
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1answer
349 views

Problem with output swing in LM358

simulate this circuit – Schematic created using CircuitLab I am working on a battery charger with indicator. I am using a LM358 to compare the voltage of my battery with a reference voltage of ...
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2answers
238 views

How to deal with strobe and balance pins of this comparator for single supply operation?

I want to use this LM311 comparator with a single supply. But these are pins called balance and strobe which confuses me. What are these for? In a forum I read someone suggests pin 5 and pin 6 ...
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2answers
169 views

Draw a circuit with a voltage divider, two comparator ICs, LDR sensors

I got this last question to practice for my exam and I got stuck. The question is draw a circuit with a voltage divider circuit, two Comparator ICs, LDR(Light Dependent Resistor) sensor Outputs: ...
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2answers
259 views

Questions regarding a comparator circuit coupling to an analog switch

This is directly related to my previous question, so it requires to first have a look at that. And the below LTspice implementation is based on Andy Aka's answer. The following circuit works in ...
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2answers
101 views

How can I modify this opamp circuit's logic

I need a system where it follows the input voltage below a set threshold voltage, and it outputs a set voltage above the threshold voltage. Below is my attempt: The circuit shown can output a set ...
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1answer
269 views

Problems while using op-amp as a comparator on a single supply

Here's my circuit: . Application: The circuit is for ground fault detection. When a fault current of 20mA flows through the primary of the current transformer (1:660), it generates a current of ~30uA ...
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1answer
175 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 ...
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2answers
722 views

Saturation problem of comparator [duplicate]

I am trying to design a comparator using a 741 IC, with a single supply of 12V. I have set the reference to 2V and I require the output to toggle between 12V to 0V. but the problem I am facing is the ...
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1answer
305 views

Capacitor weird behavior

I have hooked up the following circuit: Also, is there any possibility to create a link for the schematic? After posting it I realized it´s too small to be seen but I don´t know how to fix it. ...
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0answers
54 views

Peak detection comparator simulation problem.(Process and no VSS version)

Here is a peak detection comparator schematic and simulation,i have three question about them. 1.Why is there a high signal in C point,but not in A and B point? 2.There is VSS in this peak detection ...
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2answers
684 views

How can there even be an input voltage on a long-tailed pair?

Assuming the following: The voltage across the base-emitter junction of a BJT is constant in forward-active and saturation mode The BJTs in a long-tailed pair are normally forward-active or saturated ...
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2answers
76 views

What is the best way to design voltage monitor with tri-colour LED?

I've built a power supply with regulated +15v, +12v, +5v, -12v and -15v outputs and I'd like to build a voltage monitor to let me know if any of the rails are above or below their stated voltage. I ...
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5answers
84 views

Indicator LED pulling up line

I have a simple circuit: (Note: RN4 is currently 180 ohms. The label got left off the image.) When the 339 is setting an output low, the output is only dropping to about 2.3v, and not 0. Not low ...
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1answer
46 views

How does Shift+Turn off disable the circuit of the calculator?

How does it electronically work that in a basic Casio calculator, shift+ ac turns off calculator, is it a comparator that compares these two button states then triggers a transistor?
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1answer
379 views

will this timer/delay circuit works as intended with almost equal opamp inputs?

I just saw this video about a so called delay circuit using opamp in comparator configuration. The author mentions to use a pot as a voltage divider to feed the (+) input and the node between a series ...
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2answers
280 views

Driving solenoid valve using LM358 as comparator and ULN2003

I'm trying to drive a 12V DC solenoid Valve with following diagram. In 1st block the PC input is compared with 2.2V and its output goes to block2 and ULN2003 for driving the valve. The 2nd block is a ...
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1answer
88 views

Voltage Detection via Analog Comparator

I'm currently designing a PCB at which I have an lithium ion battery (4.3V max) attached. The battery is charged via USB (5V). The charging controller is enabled by a microcontroller which should ...
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4answers
340 views

A simple circuit to toggle between LEDs based upon input voltage

I’m trying to design a circuit to test a certain component, so I want to have different pairs of red/green LEDs for indicating whether various parts of the component are working. Indication as to ...
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1answer
56 views

Why can the offset voltage of the comparator let the transition time be longer or shorter?

When\$ V_{FB}>V_{REF}\$,then the battery enter the CV mode,otherwise,battery enter CC mode,and because inherent offset voltage of the comparator, the transition from the CC stage to the CV stage ...
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2answers
129 views

Comparator doesn't swing, is there problem with circuit?

I made this circuit to switch signals based on the 3V regulator sourcing current out VDD (out connector J2), or seeing 3V on VDD coming in on J2. I put the diode to prevent back current into the ...
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0answers
113 views

Strange output from latch connected to comparator

I'm trying to make a latch (in ltspice), so if the comparator output (A) goes low, the latch will trigger and C will go high. C should stay high, irrespective of whether A goes high or low after that. ...
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2answers
89 views

Fast modulation based on analog signal

I would like to open and close a shutter (acousto-optic modulator) really fast. Really fast in this case means 2 MHz. However, the shutter should not be modulated periodically, e.g. with constant ...
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2answers
594 views

Why such analog comparator input setup?

My understanding of an analog comparator is that you have a fixed reference voltage applied to one input and an AC signal to the other input, when the signal's voltage > reference voltage, the output ...
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2answers
77 views

Drawing TL094 Quad Comparator in Schematic

Quick question on drawing schematics, when you are drawing a quad comparator into a schematic (such as the TL094), do you use the comparator symbol four times with the IC label by it or do you use the ...
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0answers
70 views

IC for magnetic environments

I am working on a comparator circuit for converting a small AC signal to a digital (square) signal. The circuit is meant to be used in a strong magnetic environment, so the casing should not have ...
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0answers
189 views

Digital Comparator from LSB to MSB using Lookahead

This is homework to be upfront, but I'm really stuck on it and just need some kind of direction. I've been assigned to create a 16-bit lookahead comparator going from LSB to MSB using no more than 4-...
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2answers
43 views

Truncating negative results of Op amp by rail limiting

I have a signal that will swing from -5v to 5v. I am interested in the 0 to 5v part only. I will set a reference voltage and give it and the signal into a comparator. The comparator's rails are 0, and ...
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1answer
205 views

Band-pass and LM358 based rhythmic light

I was asked by a friend to build a simple circuit to have a light flash depending on the bass of a song (mainly techno music). This is my idea: The circuit works on 9V to be powered either by ...
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7answers
1k views

Simplifying many window comparators

I have 8 thermistors and I must make sure that each of them is inside a temperature window. They all have the same window and I don't care which or how many are inside the valid range, I just need to ...
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2answers
316 views

Regulating square wave signals of varying amplitude

I'm looking to capture the output of some Hall Effect sensors on a microcontroller/SBC, operating at a logic level of 3V3. The Hall Effect sensor voltage range could be 0-5V, 0-9V or 0-12V. What is ...
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2answers
270 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 ...
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3answers
173 views

Comparator, inverting/non-inverting terminal voltage is more than supply voltage

I am using Comparator (schematic shown below). I have connected output with Vcc via 2k ohm resistor, as it has open collector output. In this configuration output of the opamp should be 3.3V. But ...
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2answers
171 views

Functional principle of comparator based rectifier

I stumbled across the circuit shown in Fig. 36 on PDF page 21 of Jim William´s "High Speed comparator technieques" Application note (see Link)and also the attached schematic which shows a fast ...
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2answers
591 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 ...
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1answer
99 views

The circuit that gives the higher-voltage one of the two input signals to output

I need a circuit that behaves as the box with the question mark in the graph I drew. I tried to design a few circuits with op-amps but I couldn't get an output as I wanted.
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1answer
215 views

Problem with Constant Current power supply

I built this schematic recently. The Constant Voltage mode works as a treat, stable as it needs to be. When I insert the LM311 comparator, the circuit works fine for about 30 seconds, then something ...
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1answer
394 views

Compare three voltages by using comparator

I am working on a circuit which compares three voltages V(a), V(b) and V(c) by using only op-amps. To result If V(a)>V(b)>V(c) , V(output) should be 15v If V(a)>V(c)>V(b) , V(output) should be 15v ...
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0answers
63 views

The reason why will the VDC influence the output of comparator

There is my schematic,teacher gave us,for the comparator, Theoretically,when the black line is bigger than blue,the red one will become "signal one".but i found the vdc value will influence the output ...
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3answers
151 views

How to design a combinational circuit that finds the minimum among multiple given numbers?

There are quite a few articles (for example, this) that can be found online discussing the design of a comparator that takes two numbers (say, A and ...
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1answer
378 views

Q: Check if an LED in my circuit is still “good”

I have an electrical circuit which uses an LED, connected to a µC, to show the status of an x-ray source in another room. Obviously this LED is important to have in a working condition. Now, LEDs can ...
4
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1answer
171 views

Why does this comparator exhibit non-binary behaviour?

I'm attempting to use the TLV3501 (Datasheet) with the following circuit. Input at S_IN is around 2.5VDC (i.e. no waveform). I'm expecting to see a sharp transition between rails on the output as ...
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1answer
88 views

Positive and Negative Sense Circuit. How/why does this work?

I am trying to build a centre-off model railway controller, no reversing switch. I am working on the overload/short detection part of the circuit based on sensing the voltage across a 0R68 resistor. I ...
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1answer
388 views

Sine to square wave high frequency [closed]

I have a school project that requires a sine to square wave converter for a sine wave input of 0 - 3.1 V pk from 0Hz to 500kHz. The output must be a square wave with maximum voltage 2.8V - 3.1V. So ...
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4answers
412 views

Comparator output not fully switching on MOSFET

First Question for me. I have benefited from other answers here but have not fully resolved my problem. Here's my problem... The LM311 Comparator output does not drive the N channel MOSFET fully on....
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6answers
5k views

Why does this comparator not output a square wave?

I have a 4.43MHz sinusoidal output from an IC that I want to convert to a TTL square wave to use as a clock. The signal has a DC offset of around 2.5V and has an amplitude of about 0.5V peak to peak. ...
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1answer
1k views

5bit signed magnitude comparator

I know how to compare unsigned binary numbers. But can you help me compare any signed binary numbers? Above is my simulation but I don't know how to integrate those signed bits in my circuit ...
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2answers
193 views

How to calculate resistor values for a Foot Strap test circuit using a window comparator?

I'm attempting to create a circuit to test ESD foot straps (and wrist straps). Research has led me to a window comparator circuit for testing power supplies that I've used as a base for the drawing ...
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1answer
373 views

Comparing and adding numbers using multiplexers and comparators

Supposing I have been given three two bit numbers, a1a0,b1b0,c1c0 then what is the best way to design a circuit that gets the largest two of the three and adds them?