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

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2answers
59 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
56 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
68 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 ...
1
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1answer
39 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 ...
1
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3answers
121 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 ...
0
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0answers
61 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
116 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 ...
0
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2answers
42 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
28 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
99 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 ...
1
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2answers
144 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
120 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?
4
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2answers
232 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 ...
3
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2answers
108 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 ...
1
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1answer
114 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
votes
2answers
53 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
100 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 ...
1
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3answers
77 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
123 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 ...
9
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1answer
274 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
136 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. ...
1
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2answers
93 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 ...
1
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1answer
119 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
77 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
150 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
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3answers
248 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
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3answers
521 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
176 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
299 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 ...
3
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1answer
116 views

Designing a latch with no constant power supply

I am trying to design a latch for an energy harvesting application with a very low power system. Basically I have a setup with a 3.3V regulated output driving a circuit, which is run off a capacitor ...
2
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3answers
227 views

Using an Op-amp as comparator

I have a dual op-amp that I want to use as a comparator: Vin should be compared to Vref (1/2 VCC). This is the circuit that I am using (as I have a dual op-amp, I am using a voltage follower on the ...
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0answers
163 views

Overvoltage protection on TTL signal

I'm in need of a high temp circuit to protect a normally 0-5VDC TTL line from externally applied voltages indefinitely up to 30V (with series line resistance of 100Ohms). I'm looking at doing this ...
6
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4answers
486 views

Difference between Differential op amp. and comparator

What is the Difference between differential op. amp and comparator I know a comparator only can give me 2 values, supply values. The differential op. amp amplifies the difference between the inputs.. ...
0
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1answer
238 views

Can't turn ON transistor from output of comparator?

I can't seem to turn on a 2n2222a with the output of a LM339 comparator, as soon as the base is connected to the output, directly or with a resistor, even if the output is 5 volts, 9 volts, I always ...
4
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3answers
190 views

Comparator - get the difference between inputs?

Is there any way to have a comparator (say LM339) output the difference between its +V and -V ?? For example, if +V is 6.3 volts and -V is 5 volts, how to get a 1.3 volts signal? Put another way, I ...
2
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3answers
469 views

Three Phase Input to Single Phase Output

We have three phase input and the voltages in the three input is not the same always. Sometimes, one or two or three phase will be off. I would like to connect the phase to output which lies within ...
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2answers
892 views

threshold problem on a Schmitt trigger op amp

I have the Schmitt trigger op amp on the below diagram. (channel A & B refers the oscilloscope probes on the following figures). The resistor values are selected to set the trigger threshold as ...
2
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1answer
352 views

connection from an comparator to an optocoupler

I have the circuit below to decode a signal that is defined as Logic high >9.5 V and Logic low <6 V To determine the ...
-1
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1answer
260 views

non-inverting schmitt trigger op amp - replacing a zener diode on the input

I wonder if it is possible to replace the second figure below with the first one? Would both Vo output be the same on the figures below? If they are different, ...
3
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1answer
520 views

Low power IR detector for microcontroller wake-up

I am working on an ultra low power infrared wake-up circuit for a microcontroller (Atmel XMEGA). I have IRDA comms working but the receiver uses too much current to keep on all the time. I need to run ...
1
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1answer
224 views

Magnitude comparator implementation

I have stuck on implementing magnitude comparator for 2-bit numbers (three functions - greater, equal, less). It is pretty easy to implement it with AND and OR gates, but the point is the task is to ...
4
votes
3answers
561 views

Help understanding BJT voltage comparator

I'm trying to understand how a transistor voltage comparator works. For example I've been studying this LM339: My questions are: What are the current sources for and how would those actually be ...
1
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1answer
289 views

Problem with microphone powering up a comparator circuit

The circuit below is supposed to turn on a LED when the microphone input reaches these levels: 1V, 3V, 5V, 7V. What this circuit does in real life is when we turn on the power, all 4 LEDs light up. ...
0
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1answer
144 views

newbie: comparator adjustable level shift

I'm trying to build a simple fpga logic analyser and wondering how to best design the input circuit. I would like to support 8 channels, voltage between 0-5V, with a adjustable threshold range (lets ...
1
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3answers
952 views

Can you feed in a voltage higher than your supply to the input of an opamp?

I have a 28V digital signal. 28V being logic 1 and 0V being logic 0. Can I feed the 28V into an opamp (Vcc @5V) to level shift it ? Or will I have to create a voltage divider to bring the 28V < ...
7
votes
1answer
175 views

Issue with TI comparator

I'm having trouble with a comparator from TI (LMH7322). I use it in the circuit shown in the attached image "Comparator_1". Outputs go to an FPGA. The circuit is supposed to take a single ended input ...
2
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2answers
499 views

Techniques for analyzing Comparator circuits?

I'm looking for some general guidelines/equations I can use to analyze circuits which use comparators. In particular, I'm interested in hysteresis. For example, take the following open ...
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1answer
1k views

Generating sawtooth signal out of square/triangular signal

I want to create a sawtooth signal generator. I know, how to build op-amp comparator to create a square wave. I also know, how i can get triangular signal by integrating comparator output with op-amp ...
0
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1answer
309 views

USB ground on MSP430 Launchpad interfering with Comparator_A input voltage

I'm trying to read an audio signal from an Android phone as a serial input to an MSP430G2553, adapting this design to use the MSP430's onboard comparator module instead of an LM324. The Android code ...
2
votes
1answer
243 views

Op-Amp Comparator precision voltage

I need to trigger a speaker if my input voltage is higher than 0.6 V, otherwise the speaker must not be triggered. That's the reason I'm using an AMPOP Comparator: and, as far as I know, the ...