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

learn more… | top users | synonyms

0
votes
2answers
33 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 ...
0
votes
2answers
60 views

lm324 if i feed it with Vcc but not grounded it,what the value isee on GND pin?

I have lm324 in my circuit and I connected Vcc pin To 5V, but GND pin is not connected (float), so What the value I see on GND pin ?
0
votes
2answers
86 views

Did my comparator break?

I have two inputs for my LM393P comparator (https://www.rcscomponents.kiev.ua/datasheets/texas_instruments-lm393p-datasheet.pdf). I have checked these two inputs with the analog inputs with my Arduino ...
1
vote
1answer
51 views

Current Sense Amplifier and Voltage Comparator in Same Pacakge [closed]

I am in need of sensing the current in a circuit and cutting off power when current exceeds a threshold which should be about 2A. It seems that everything I've read recommends using separate "current ...
1
vote
1answer
48 views

Need additional capacitor for comparator?

I am designing a circuit for interfacing the frequency input signal. I used simple Op amp inverting comparator with hysteresis, as below The op amp is single powered by GND and 5V. Otherthan ...
0
votes
2answers
76 views

How to protect mcu pins from reverse voltage [edited]?

I am asked to build a 5 V /24 V circuit interface using an ATMEGA328P.For that i built a little comparator circuit to get a 5 volt level on a I/O pin . My problem is that the output of the ...
0
votes
2answers
53 views

Level shifting digital signals with a comparator

I'm trying to understand the voltage levels associated with a comparator used for level shifting digital signals. The comparator is the MAX995. The input voltage levels are +1.5V/-2V, and the output ...
1
vote
2answers
76 views

Understanding electrical characteristics of comparators: input offset voltage and open collector output

I have two questions regarding the electrical characteristics of comparators: Is there a way to adjust the input offset voltage of a comparator to fit a custom application? Which comparator ...
0
votes
3answers
104 views

How do I make a 4-bit comparator?

I'm making an ALU (Arithmetic and Logic Unit), I've made a 1-bit ALU with ease, but 1-bit (1b) is impractical, who would need only 1b? I've made that adder/subtractor and I need the comparator ...
0
votes
1answer
58 views

Schmitt trigger design to control lead acid battery charger

I've found a very good explanation on schmitt trigger circuit design here -What is a Schmitt Trigger and its application exactly? But the design is done considering same reference voltage and the ...
-1
votes
1answer
151 views

Using GPIO pins as software I2C pins and finding analog value of those pins

I am using AT32UC3C microcontroller which has 64 pins. I am using gpio pin PB01 as SCK and gpio pin PA04 as SDA and ticking then manually high and low. These pins are configured as GPIO_OPEN_DRAIN and ...
1
vote
2answers
81 views

Detect power supply voltage threshold, while consuming very low current

Lead acid batteries get damaged by over-discharge somewhat like lithium polymer batteries. I need a circuit that will cut off the load from the battery when it drops below about 10v. That is the easy ...
2
votes
1answer
54 views

Solving Schmitt trigger circuit using the superposition theorem

In order to solve a Schmitt trigger circuit implemented with an op-amp (or a comparator) connected in positive feedback, this wikipedia page uses the superposition theorem. My question is : why can ...
-1
votes
1answer
55 views

Help with this MOSFET comparator

So I'm building something and I figured I needed a mid-voltage Comparator or symmetrical Schmitt Trigger (by losing the MOSFET half of the V2 side). For reasons of "just-because", I decided it should ...
0
votes
3answers
90 views

How to light an LED controlled by a photo-diode

I need to get an LED shining brightly when a photo-diode (in the local store it is sold as such, but of course it could be something else, as suggested in the answer of WhatRoughBeast) receives some ...
3
votes
3answers
314 views

Discrete Schmitt Trigger Design (0v-5v logic)

I designed a Schmitt Trigger with discrete components (using an emitter-coupled pair) that operates with a Low Disable Trigger of around 3.5V and a High Enable Trigger of around 4V on circuit ...
-3
votes
1answer
75 views

How to Design Switching Circuit Using Comparator

How do I create a comparator circuit that compare voltage from 12V battery when the battery drain to a certain level, let say drain to 1.5v, the comparator will produce an output that will trigger ...
1
vote
1answer
63 views

Possible ways of protecting comparator input from coupling?

Overview So as I'm implementing some logic with a comparator, I've run into the problem of the output swing coupling with one of the inputs, and now I'm searching for possible ways to minimize or ...
1
vote
2answers
62 views

Schmitt Trigger Functionality Not Working, Questions

I'm trying to build a Schmitt trigger like the one described here: http://pcbheaven.com/drcalculus/index.php?calc=st_nonsym_sp However, it isn't working as expected, and I'm thinking it may be due to ...
0
votes
0answers
29 views

MN1381 replacement for BEAM robotics

The MN1381 is a 3-pin voltage detector IC which is used for many small robotics - especially solar powered machines. It detects the voltage between two pins and generates a high output on the third if ...
0
votes
0answers
15 views

full inverter circuit with a buzzer circuit [duplicate]

I analysis the Lm324 circuit and i understand how it work without the C9 and C11 , but I want to know what the function of these tow capacitors.
1
vote
1answer
86 views

Measure the maximum value of an exponential analog signal and provide a constant supply having that same value

I need to detect the exact time for which an exponentially decreasing analog signal is equal to the half of its maximum value. I'm using for that a digital-output comparator but I have a big problem ...
-1
votes
1answer
71 views

My Tiny Comparator

I just can't seem to get this to work. simulate this circuit – Schematic created using CircuitLab The diodes were supposed to prevent this from going in "reverse-mode", should the ...
1
vote
2answers
63 views

Problem with using comparator to amplify signal

I want to use LM293(comparator) to amplify signal. The input signal from 0 to 2.5V, and make the output signal double(from 0 to 5V). Then I use the LM293, and I do the simulation first, it works ...
1
vote
1answer
81 views

H-Bridge controlling circuit

I'm in need of an H-Bridge capable of driving moderate-high current for motors on a small car (7A peak, 2-3A nominal, 12-14 VDC), and I'm hoping to control it with two (2) digital pins (5 VDC). I've ...
1
vote
1answer
93 views

Best way to compare value in register with constant assembly AVR

I am newbie in assembly and AVR, I wonder what is the best way to compare two values like in C ...
0
votes
2answers
121 views

Recommended approach to create a lead acid battery level circuit

I want to build a battery level indicator circuit for a 12 V sealed lead acid battery. The battery indicator circuit will have two functions: It will power 4 LEDs to show the level of the battery ...
2
votes
4answers
325 views

Question about 1-bit Analog-to-Digital Converter

I am working on a research project, and for a part of it I have to turn an analog signal into a digital one. Now, electronics is not my forte so I don't know what I am doing and am feeling around in ...
0
votes
3answers
219 views

Fast 220v AC power failure detection

I'm building an AC-Detection circuit. I want to detect when the AC power has failed ASAP so that I can react very quickly. (like 1-3ms should be enough time) This was my first idea. It works in ...
0
votes
1answer
75 views

Implementation of 4-bit subtractor

How to implement subtractor of two 4-bit numbers using subtractors of two 1-bit numbers as a module(no assembler coding, just expressions in boolean algebra)? If there are four 1-bit subtractors, how ...
-1
votes
2answers
117 views

How exactly does a comparator work?

How exactly does a comparator work? Comparators have many uses and its concept is not too hard to grasp. What I don't understand however is how exactly it compares two voltages. How does it know ...
2
votes
1answer
485 views

Can someone explain how this transistor comparator works?

I am looking to make a comparator using transistors and I stumble across this circuit claiming to be one: Unfortunately, the description that came along with it leaves a lot to be desired, ...
0
votes
2answers
78 views

Timing circuit with op amps and capacitors

I understand how a basic comparator op amp works and how a capacitor charges individually, but I can't seem to put it all together to make this circuit. I think I might be messing up with the voltage ...
-1
votes
1answer
125 views

Comparator model suggestion for overvoltage protection circuit

It's a pretty simple circuit. I'm measuring a voltage with an ADC, which has a max input of 5V. The signal I'm measuring goes to the drain of a F12N10L MOSFET. The MOSFET's source is connected to ...
0
votes
2answers
247 views

Comparator - Short circuit indicator. Possible to design a bi-color LED version?

Recently, I began work on a adjustable regulated power circuit in search of a short circuit protection / indicator add on. A fellow forum user issued a solution that involved an LM321 as a comparator ...
0
votes
0answers
23 views

How does this regenerative latch push the circuit into saturation or 0 V

I am looking into this circuit which is a comparator latch. In the above diagram there are 2 gain stages. For the first 1 , a PMOS is used as a load and an NMOS for the second stage. If the ...
0
votes
1answer
51 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 ...
0
votes
5answers
218 views

Reducing the voltage drop on a simple comparator driving a MOSFET to avoid LiIon overdischarge

I would like to use a LiIon cell recovered from an old laptop to power my bike light (a bulb one, 2.4W 6V). I thought about using an opamp controlling a MOSFET to avoid overdischarge (MOSFET ON for ...
1
vote
2answers
164 views

Where am I going wrong with the comparator in MSP430?

I am getting up-to-speed on the TI MSP430. I am attempting to write code in C to access the built-in comparator on MSP430G2553. I've got a simple program for the comparator but I must be doing ...
1
vote
0answers
40 views

Port A digital output set up on pic16lf1827

I am having difficulty moving my code from port b to port a on pic. I am looking at adc disabling and also comparator disabling, but not having much joy. Anyone see what I'm doing wrong? ...
2
votes
2answers
106 views

Muxes, Adders, Comparators, and Gates

This question is actually from one of my previous discussions, which I still don't understand how to implement. The goal is to use abstraction to design a circuit, which converts two-digit ASCII ...
1
vote
0answers
71 views

How do I do signal comparison without using opamp?

I want to remove the opamp IC seen in the schematic below with the least number of transistors possible in order to simplify the circuit, reduce cost and increase switching performance when used with ...
-1
votes
1answer
76 views

comparator problem

where is the mistake in my circuit? i attempted to create simple continuity tester, image really explains it pretty much. IC - ne5532p PS: i know reference voltages on two op amp (+) terminals are ...
0
votes
1answer
399 views

How could I go about building a 2-bit comparator that compares two 2-bit numbers and determines whether one is greater than or equal to the other?

Using an 8:1 multiplexer, I understand there are three inputs, so I'm not sure how I'd go about getting two 2-bit numbers, which would be four variables, not three. Any pointers on how to get started ...
0
votes
2answers
161 views

Understanding decoders and comparators

How can I implement the comparator of two 2-bit numbers using decoders DEC 2/4 and required logic gates? That comparator will be used to compare two 4-bit numbers. The comparator only has one output ...
1
vote
1answer
268 views

dsPIC33E comparator interrupt doesn't occur

I'm currently trying to get the comparator on dsPIC33EP256GP502 works, but get stuck in the comparator interrupt. Basically what i want to do is just using the comparator to compare two external ...
2
votes
2answers
122 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 ...
1
vote
1answer
114 views

Comparators as op-amp integrator

So I figured I need an audio range function generator and was thinking of generating a square wave with a 555 and then using op-amps to integrate it into a triangle and sine. Since I happen to have ...
0
votes
2answers
201 views

Purpose of gate driver in Class D amplifier

Can somebody explain to me why we need MOSFET gate driver in class D amplifier like in the picture below(common class D schematics)? What I don't understand is if we for example have 9V rails, then ...
9
votes
4answers
1k views

Controlling heater with PWM through MOSFET

I'm trying to control a heater coil (resistance ~0.9 Ohm) with PWM using a MOSFET. PWM modulator is based on LM393, MOSFET is IRFR3704 (20V, 60A). If I place 1k resistor in place of heater ...