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

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328 views

What's the purpose of the 1M resistor in this comparator circuit?

I find this circuit from ON Semiconductor's LM211 datasheet. There is a 1M resistor from negative power rail to the 'reference' input. ON doesn't describe the circuit's function. I think it's a ...
1
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2answers
86 views

What type of Op Amp or comparator has a schematic symbol with hysteresis like symbol

I already know it is not a schmitt trigger, it looks like it is used as an open loop amplifier taking a reference voltage on the (+) and the V0 is fed into a schmitt trigger. I have no other data. ...
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2answers
43 views

The direction of the bias current of LM311

I thought the conventional method to denote the direction of the bias current is to precede the IIB parameters with the '+' or '-' flag in the 'electrical characteristic' table, '+' indicate the bias ...
2
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4answers
110 views

Why do they usually make comparators open collector?

I never see open collector opamps while I frequently see open collector comparators. What is reason for preferring open collector output in comparators? (Inside of LM193.)
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4answers
242 views

Is there a clever way to prevent a window comparator from oscillating?

Here is my schematic It's basically a crude battery level detector (I am very aware that this isn't the best way to guage battery life, I'm not here for that) it's not crucial that it is super ...
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3answers
115 views

Are there examples of chips where comparing 2 against zero would be slower than comparing 1 against zero?

This question on StackOverflow goes like this which is faster - while(1) or while(2)? Asking which of two infinite loops is ...
2
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4answers
226 views

Need help explaining this circuit and how it is dimensioned and designed

I'm working on a project to school where I'm designing a battery charger with battery status indicator, and I found this circuit online: but to include it in the project, I must explain how it ...
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2answers
68 views

High voltage input window comparator

I'm trying to find pieces (comparators or op amp) to make a window voltage comparator. My window range is 180VDC to 230VDC. Did you ever heard of high voltage input comparators? I don't need a high ...
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1answer
77 views

Why does my comparator not give an output?

I am new to doing electronical things, so I bought some components and I am just trying thing out. Now, I am using a LM 2901-comparator, whichs documents you can find here. Using a power supply of ...
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2answers
88 views

Handling high voltage input range to comparator

I'm using 3 comparators for sensorless back EMF commutation of a BLDC motor. This involves comparing the voltage of each motor phase to a neutral point to detect zero crossings. See Microchip AN970 ...
0
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1answer
60 views

Difference between LM339D and LM339N

Im trying to understand different comparators. What is the difference between different LM339 ICs, especially between LM339D and LM339N?
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4answers
156 views

op amp as comparator/switch - strange behaviour

I have the following schematic (extract): The purpose of this is to enable a pin (chip enable) and to disable the 5V supply ("5V consumer") if the threshold at the signal IN is above a certain ...
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2answers
125 views

Op-Amp comparator or amplifier?

My colleagues and I are having a discussion about the circuit below, specifically: Is the op-amp being used as a comparator, or as an amplifier, or something else entirely? The circuit is a negative ...
1
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1answer
75 views

Detect a keep-alive signal

Reason/Background I have a raspberry pi (garage) that's doing some security-related monitoring, and generates a "keep-alive" signal. I would like to have an alarm go off in a separate place (attic) ...
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1answer
39 views

Multisim producing very low comparator output voltage

In the images below I have the same schematic in multisim, one snapshot for each state of the comparator. I've got the VCC pin connected to 12VDC and the ground and VEE pins to ground. There is a ...
0
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2answers
111 views

Hysteresis not working properly

This question is related to my previous question about the battery charging and discharging. Here is the link to my previous question. I have made a small change in my previous schematic, which is ...
2
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2answers
150 views

Battery charging and discharging problem

I have designed a battery charging and discharging circuit. The main purpose of this circuit is to charge the battery and then discharge, one operation at a time. I have also added a hysteresis of ...
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2answers
313 views

Help with Piezo conditioning circuit schematic

I have the below schematic that uses a piezo sensor as input and relays that information to an Arduino board for processing. The schematic came from a few folks over at MIT that built a ping pong ...
2
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2answers
52 views

Flipping Output Logic

I have the following circuit: The diagram above has a pot between VCC, LM393 and Ground, on my board pictured below this is replaced by a voltage divider with two 10k pots. It looks like this: ...
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3answers
187 views

A few OPAMP questions I have a hard time finding the answers to [closed]

I have a few questions, which, albeit, may seem pretty obvious to a lot of you, but I couldn't find the answers myself, so apologies in advance. Also, the pictures are pretty rough, I know, but that's ...
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0answers
46 views

BMS: Comparator using TLV1702

I was asked by my boss to develop a system to manage an automatic door battery system. The goal is for when, for example, the power goes out, you get home and want to open your garage door, with this ...
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2answers
74 views

How to find exact low voltage and high voltage values?

How to find the Hysteresis comparator exact "V high and V low" values
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1answer
74 views

How to get the full Vcc output from comparator?

I am working on a circuit using a comparator for a school project, but in testing it is not acting as expected. Specifically, the output is not going all the way to the higher rail voltage attached ...
0
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2answers
93 views

Rail-To-Rail Comparator Design

I'm trying to detect small current pulses (~1.5mA). Currently I'm generating a ~20mV pulse on a sense resistor and feeding that to the input of an opAmp with some hysteresis. I'm having a bit of ...
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1answer
64 views

Comparator: What is appropriate for comparing ranges of about 50-100 mVs? Can I use an LM741 op amp?

I am attempting to create a high voltage signal when the voltage from a sensor I am using drops below a certain threshold, which will be between .05 and .1 Volts. I was trying to use an LM741 op amp ...
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3answers
202 views

How do you set the reference voltage for a comparator?

I know this is certainly a beginner's question but am a first year student so hopefully I can be forgiven. I was looking through a electronics booklet provided by IKES website, and it's talking about ...
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0answers
313 views

Solar cell powered supercapacitor charger with strange output voltage regulator problem

I have a strange problem in a low power circuit design. I designed a buck-boost converter as a maximum power point tracking circuit (control the output of solar cell within a small voltage range ...
3
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1answer
178 views

LM324 comparator IC getting burnt

I am using LM324N as a comparator which has Reference voltage of 1.2V to +ve terminal. It requires supply voltage VCC=24V & VEE=Gnd.When input is 0V Vout=24 and when input= above reference voltage ...
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2answers
50 views

Comparator won't flip to HIGH

I am learning to use a comparator (LM393N) and running into trouble. No matter what I do, the output is always LOW. I am running off of a 9V battery, and I've added a voltage divider to send half of ...
0
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1answer
46 views

LM393N with hysteresis and potentiometer

I am having a bit of a problem with this next circuit: The problem is, when there is 0V at the base of Q1 and when the potentiometer is set close to 100 kOhm. Because of the hysteresis set on LM393N, ...
2
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2answers
241 views

Maximum voltages of an op amp comparator

If I have an op amp setup as a comparator, e.g. like this one: I know that Vo represents the difference in the input voltages, but is there a maximum value these voltages can be? Is there a limit ...
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2answers
166 views

Detecting if one voltage is bigger than another without an operation amplifier (OP-AMP)

I can't get my hands on an OP-AMP chip right now so I'm wondering if there's any way to detect if one voltage is greater than another voltage without the use of an OP-AMP. I've heard differential ...
4
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2answers
156 views

Smallest Voltage that a comparator can detect

What is the smallest voltage a comparator can detect? Is it possible to set the reference voltage to a few millivolts, just above the noise margin for using a comparator circuit?
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336 views

Compare two voltages and output the lower of the two

I am working on a circuit that is connected to a 10V supply (can supply about 1-2mA). We have two signals, let's call them S1 and S2. We also have an input to the circuit called IN1. My goal here ...
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2answers
116 views

Checking whether two voltages are similar

I am pretty new to electronics so this may seem like a basic question, but how could I check whether two voltages are similar? For example, say I want to check whether | V1 - V2 | < 1.5V and output ...
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1answer
188 views

How to check if a comparator is broken?

I have just started experimenting with electronics and am concerned that I may have destroyed my LM339 comparator circuit. As a basic test, I had a 3.0 volt power supply hooked up to the Vcc pin and ...
2
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2answers
73 views

Use interrupt to determine a change in IR detector

I have build a schematic to read a counter. The counter has a white point at one of the digits, that I detect with a IR transmitter-receiver. The voltage at the receiver changes from 2.2 to 2.5 volts ...
0
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3answers
135 views

LM311 comparator : strange output levels

I have the following circuit, where I put R52 = R53 = 2700 Ohms : Triggering levels are of 1V and 2V approximately according to my computations, that is okay according to the following figure ...
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3answers
83 views

Calibrating the output voltage

I have a device which has a 16 bit D/A converter which through an analog linear circuit generates an output voltage between -1V and 1V. I have 32 of such channels on my device. simulate this ...
5
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1answer
145 views

What is the difference between “opamp” and “comparator”?

In electronic part seller websites, I see that there are two separate categories for opamps and comparators. As far as I know, an opamp itself is already a comparator if you don't connect a negative ...
10
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1answer
426 views

Can I use differential I/O pins of FPGA as high speed comparator?

High speed comparators are rather expensive and speed is what FPGAs are very good at. On the other hand, FPGAs (in my case: XC3S400) have paired differential pins in each bank that their voltages are ...
0
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1answer
187 views

AD9850 comparator problem. How to calculate is frequency?

I want to convert a sine wave produced from AD9850 (opens *.pdf) into square wave with its inbuilt comparator. AD9850 has a fast comparator with 3ns rise/fall time and propagation delay= 5.5ns. ...
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2answers
112 views

Preset ratings for a comparator circuit

1)What are the rating for these kind of presets? I need the maximum current they can withstand without any harm, (Imax). [data need for a 100k preset] 2)I'm hoping to use this kind of ...
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1answer
164 views

Comparator circuit to detect working alternator

I'm very new to electronics, but am trying to build a device that should be attached to a motorcycle (Arduino based sensor board) which should only draw power when the engine is running; specifically ...
2
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0answers
91 views

comparator input latches high?

I am using a a TI TLV3202 comparator (U2B) with a bridge circuit as shown in the schematic below. It is followed by a DG4157 analog switch. This is related to this question I had asked earlier. ...
2
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1answer
204 views

LM311 comparator output

In the LM311 circuit below that is used as a comparator, how does voltage at the reference (- Input), affect the output? For a sine wave, would having a higher voltage at the reference increase or ...
3
votes
3answers
271 views

Basic comparator strange problem

I am trying to create a super simple Low Battery alert monitor, by utilizing an open-loop comparator. LBO is active-low - it's connected to a TTL input pin of a uC, running from same Vbatt voltage. ...
5
votes
3answers
1k views

Detecting an open circuit by sensing current flow using a shunt and comparator

I need to detect if a load resistor is taken out of circuit. The load resistor is a photoresistor and can vary from 50k\$\Omega\$ up to 2M\$\Omega\$ and is driven by +5V to ground. The approach I ...
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3answers
226 views

Amplify .7Vpp square wave to 5Vpp square wave buffered to go over a 15-50 foot cable

I've got a sensor that outputs a .7Vpp square wave at 36kHz-60kHz. I need to take that square wave and amplify it to 5Vpp, as close to 0V to 5V rails as possible. Then I need to send that signal ...
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1answer
377 views

How to control squarewave oscillator with comparator output? (LM339)

I have LM339-based resistive water detector, which produces nice (almost) rail to rail output (see Schematics for device, which reacts to water?), and also LM339-based squarewave oscillator, taken ...