Questions tagged [comparator]

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

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62 views

LM311 overheating

I breadboarded the circuited below. Within seconds of operation, both the L7805 and LM311 start to overheat very badly. I tought it had something to do with the coupling capacitor or the AC signal so ...
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Op-amp input voltage gets clipped off

I'm trying to build a simple voltage comparator using LM324N. Here is the circuit: simulate this circuit – Schematic created using CircuitLab The strange thing that happens is that after apply ...
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36 views

Using analog comparators to get 2 different outputs depending on the input

I am trying to use analog comparators to get two different output voltages, 6V out when the input voltage is -8.5V <= Vin <= -2V and -3V out when the input voltage is -2V < Vin <= 9.5V. I ...
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70 views

How does the comparator in the NE555 compare its two inputs?

This is a circuit diagram from the very detailed and helpful NE555 Wiki page. The yellow and red coloured segments are comparators, comparing Thresh and Trig to fractions of Vcc. If I know how a ...
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120 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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77 views

Making a light detector using a phototransistor and an open drain comparator

I want to make a light detector using a phototransistor. To do that I connected a phototransistor and apotentiometer to the open drain comparator as in the diagram below. When the light is dim, ...
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25 views

What's the small signal model of this CMOS differential pair?

I cannot derive the small-signal model for this differential pair: My goal is to observe the effect of transistors M6 and M7 which should create a hysteresis effect in the output equation for Vo1 or ...
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61 views

How about this design of analog comparator? [closed]

These day I design some transistor logic circuit for the high voltage sensing. I complete other necessary logic gate but, I didn't decide comparator circuit yet. Are there any improvements to this ...
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30 views

Sensor Signal Open-Circuit/Short-Circuit Faults — Trigger Shutdown Circuit

I am working on a project where I use the signal from 2 sensors in order to determine whether I want to trigger a timer circuit that then propagates a signal to latch an LED. The sensors give voltage ...
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29 views

Beginner Question: Get 2 Reference Voltages for Comparator using Voltage Regulators

I'm working on a project where I have a 12 V voltage supply. I need reference voltages of 4.5 V and 3 V which will be each be used as the Vref for a comparator. I am aware that I shouldn't use a ...
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57 views

OpAmp/Comparator for AC current detector circuit

I am trying to complete schematic for current detector. This is addition on How to build AC current sensor circuit for ESP-01 GPIO. By googling and researching I came with following schematic which I ...
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83 views

Need help to correct circuit

I am using this circuit to detect whether or not electricity is being consumed. There are two sensor sources (CT1 & CT2 ) where a CT coil will be installed. When electricity passes through that ...
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66 views

IR sensors not working in sunlight

I am using an ITR20001/t optical sensor for a no-touch application. It is working properly indoors, but if I put the setup in sunlight the IR receiver is enabling automatically. How can I overcome ...
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54 views

LM393 Ref voltage does not seem to work

I am trying to build a comparator using the LM 393. Just a basic design where I my Vref 3V is produced by 100/150 Ohm voltage divider. The input signal is a pulse from a geiger sensor as below: ...
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31 views

Is bandwidth of cmos comparator important?

The concept of bandwidth is developed based on small-signal analysis. However, comparator works usually under large-signal conditions, and transistors are not in saturation region, since comparator ...
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1answer
60 views

Op-Amp dynamic hysteresis

What is dynamic hysteresis in Op-Amp? I read section 4.3 of the this App Note and was not clear. Can someone explain me why this is happening?
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Circuit question for LM358 and NE555

I have made an IR proximity sensor which works fine when an LED is connected. Figure 1: This is the IR receiver and emitter part of the circuit. The white LED is connected to ground via a 270 ohm ...
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50 views

Am I using this LM393A comparator incorrectly?

I've read about comparators and from my understanding, you've got 2 voltage inputs: reference voltage usually connected at the inverting input and Vin i.e. voltage you want measured usually connected ...
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63 views

LVDS comparator re-triggers on falling edge

I have a problem with a simple comparator circuit. The comparator takes a 1 PPS (pulse-per-second) signal as a single-ended input, and outputs an LVDS signal. The issue is that the comparator, ...
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118 views

Comparator as operational amplifier

Using an operational amplifier as a comparator was asked quite a lot times here, but how does it behave the way around? I've a really cheap one in my circuit with low hysteresis and a MOSFETt push/...
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120 views

LM339 comparator trigger SR latch

In this circuit we have a LM339 comparator which compares input signal with respect to the threshold value which is 4 volts. This is the output of the transient analysis. If the input signal is ...
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98 views

Why does my LM311 comparator's output seem to be inverted?

From what I understand, the potential difference between its output pin (COL OUT) and GND is equal to the voltage of source when the potential of IN+ (pin 2) is greater than IN- (pin3). The opposite ...
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44 views

Operating Point of CMOS Folded Cascode Differential Amplifier

Designing a pMOS folded cascode differential amplifier to be used as a comparator with input 'IN' and ground as the reference input. Now, there are tons of different architectures that one could use, ...
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55 views

How do I calculate the power consumption of the polarity detector circuit?

What method can I use to calculate the power consumption of this block? In the paper it's equal to 3 μW at 1.5 V. The datasheet of the piezo sensor. The datasheet of the MAX9119 comparator. Circuit:
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73 views

“Voltage divider holds 37% of supply voltage at negative” wrong in textbook

In my textbook, it states that "the voltage divider of R3:R4 holds 37% of the supply voltage at negative". However, I think it should be 63%.
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52 views

Using LM393 For SLA Battery Management

I had an old 6V SLA battery laying around, so I thought that it would be a great exercise to design a Battery Management circuit for it. Is the following circuit, based on the LM393, sufficiently good ...
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44 views

Method for connecting Unused comparator pins

I have a dual comparator and one of the comparators is not being used. I know with an op amp you're not supposed to connect the inputs directly to ground. The way I do it with op amps is with a ...
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40 views

Comparator logic control from a potentiometer

I'm trying to think of a solution to a problem. I plan to use a 10k linear fader to control a voltage controlled amplifier (THAT 2180), however I would like to be able to control a logic high and low ...
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49 views

Unable to connect amplifier output to comparator in opamp

I am amplifying a signal for a current transformer (CT) with an op amp. This amplified output signal I need to compare using op amp comparator. The supply voltage is 12V and the IC is an LM358. When I ...
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81 views

Thermocouple comparator choose

I measured the parameters of a thermocouple (R1). R1in=5 Ohm, V=1..10 mV (measured by multimetr). Ipositive = 5v/20000 = 0,25mА, and Upositive max = 0,25 * 0,001 * 100 = 25mV I have lm339, lm324. ...
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106 views

Comparator hysteresis input signal filter

I need to heavily low pass filter an input to a hysteresis comparator, but due to the fact that R1 is one of the components setting the hysteresis, I can't add additional RC-circuits in series with it....
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48 views

Building a 2 bit comparator tips and tricks with truth table

Build a 2-bit comparator using either two 74151 8-to-1 MUXs or two 3 to 8 binary decoders. Additional gates such as AND, NAND, OR, NOR, inverters can be used. So I got this question while coming ...
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Can someone help me understanding the working of 3-stage comparator/ discriminator, shown in attachment?

I am working on a project and I need a high DC gain comparator for it. M1,M2 are tge main differential amplifier and M1a, M2a are used for hysteresis. As per my understanding its a 3 stage comparator: ...
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450 views

What's the purpose of a diode to Vcc at an LM339 output?

I'm unable to figure out the purpose of this diode (1N4148) from the output of the comparator (LM339N) to VCC. It's not clamping anything as there's nothing that can pull that rail beyond VCC.
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87 views

Trigger relay at different voltages with voltage comparator

TL;DR - I need help on making a relay with voltage comparator which accepts two reference voltages. Aim My project needs to run a Raspberry Pi on solar power. Solar panel will be connected to a power ...
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59 views

NiMH battery pack charging circuit using Solar panel [Help]

Recently I have been working on a NiMH battery pack (7.2V / 2100mAh) charging circuit powered by a 12V solar panel. With some research I found charging NiMH takes different forms by measuring change ...
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100 views

Wiring a BJT differential amplifier in a circuit

I need to switch a 12V relay when an input signal passes a certain voltage threshold. I use this popular BJT amplifier: In my case: VCC = 5V ...
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149 views

Why can't a single-supply comparator handle negative inputs?

I tried simulating a basic comparator configuration in Proteus with only a single supply. The reference/trip-point is 2V. However when I simulated the DC transfer curve, all negative input voltages ...
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72 views

Photocell comparator circuit using LM339

How to prove this mathematically?
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95 views

Op-Amp Comparator Testing

I am having this op-amp Comparator. My circuit is similar to this circuit present in the datasheet of the IC, page 21. I have this circuit now in my board which I want to test. I have never tested an ...
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132 views

Oscillator circuit using comparator and opamps

All opamps are ideal and Rx = 2R in the figure. The comparator is a nonlinear block which operates as follows: if its input Va < 0, its output is +1V. If Va > 0, its output is -1V. To simplify ...
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106 views

Comparator simple build [closed]

So I was trying to learn about what comparators do and I did. They compare 2 voltages and if the voltage at the V+ pin is bigger than the voltage at the V- pin they output 1 else they output 0. Life ...
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91 views

IC design to amplify from microvolt to volt for making a comparator

I am developing an IC in CMOS technology which, among many other things, I need to compare one signal with another. I need a square wave signal above a limit to result in VDD, and signals below that ...
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249 views

Can a voltage comparator be constructed from NPN BPJ transistors and resisitors alone?

I'm working though some basic logic circuits with my niece and nephew and wanted to implement elements with transistors before we get more complex and replace modules with ICs. I know this is trivial ...
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68 views

What is the role of R1/C1, R3 in this slicer circuit?

I found the following data slicer circuit: simulate this circuit – Schematic created using CircuitLab The input is a simple NRZ (PAM-2) signal between "Vhigh" and "Vlow" (=...
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101 views

Overvoltage protection using opamp

This circuit is used for overvoltage protection, I can see that the two opamp are comparators that will output 0 or 5V depending on the input, but can't see how it is protecting from overvoltage. ...
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38 views

Comparator H Bridge current sense negative voltage input

I'm using lm339 basic comparator to sense current from an H Bridge. Current limiting was done somewhat successfully with acs712 after removing the capacitor from filter pin for limiting the bandwith. ...
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375 views

Custom 25 A mains inrush current limiter design review

I've designed an inrush current limiting circuit and would welcome a review from experts with more experience with this sort of thing. The load will be around 50 x 19 VDC @ 3.5 A linear power supplies ...
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79 views

Comparator have hysteresis with pull-up resistor?

I didn't add any hysteresis to below circuit but there's ~500 mV delay between output going high and low, output goes high at 7.5 V but goes low at 7 V: simulate this circuit – Schematic ...
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110 views

FET Written Inside Comparator/Op-Amp Symbol

I'm in the process of importing a bunch of old schematics from a 70's era synthesizer into KiCAD. In the process I've come across a symbol that I can't make sense of. It looks like this: Does anyone ...

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