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Questions tagged [comparator]

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

4
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3answers
94 views

UVLO for Energy Harvester circuit

A good background on the problem can be found in the document: (Under Voltage Lock-Out Design Rules for Proper Start-Up of Energy Autonomous Systems Powered by Supercapacitors). The above document ...
10
votes
2answers
525 views

How are such low op-amp input currents possible?

I understand that op-amps have low input currents; that's one of their defining characteristics. But looking at the datasheet for the LMC6001 (amusingly called an "Ultra, Ultra-Low Input Current ...
-1
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1answer
61 views

window comparator understanding

I dont understand the output of the window comparator. How does the window comparator switch from HIGH to LOW. There is no transistor or anything else. Only two OPAMP which outputs are put together. ...
0
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0answers
36 views

Comparator resolving input voltages close to vdd

I have a design problem to solve. The problem statement goes as follows: "Design a clocked comparator resolving input voltages close to vdd dissipating less than 100 uA". What does "resolving input ...
-1
votes
1answer
80 views

where to connect the offset nulls in a comparator circuit [closed]

I made this circuit but no matter what the input Voltage is, the output stays high and the led lights. Is it because of the offset voltage ? And where to connect the offset nulls to make the output ...
0
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1answer
55 views

Adjusting duty cycle without affecting frequency of a VCO

I've looked around the internet for a simple voltage controlled oscillator that is able to produce various waveforms in phase with one another. I asked about it in this site and was directed to a dual ...
1
vote
3answers
137 views

LM339N - Comparator #4 not working as expected (always low)

I've designed a circuit for a battery indicator for my 18V Li-ion battery pack, based off this example here: https://www.electroschematics.com/8347/24v-battery-level-indicator/ I have it laid out on ...
0
votes
1answer
69 views

Analog Comparator Design

I've been brushing up on my analog design, and have some questions regarding improving the design of a simple comparator. It's been a while since I got this deep into it. I'm trying to implement it ...
0
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2answers
61 views

Why the don't the theoretical and practical output of comparator match for small input?

I have been using TL084cn IC which is basically an amplifier IC. I was giving the input to it of amplitude around 450mv. This IC is capable of providing a slew rate of 13. The Vcc given to it ...
1
vote
5answers
94 views

Schmitt Trigger hysteresis

I am studying comparators and Schmitt triggers. And I did not find anywhere how to choose the value of hysteresis. I understand its purpose and I know how to calculate it. But what value is needed for ...
0
votes
1answer
42 views

Basic circuit to turn on LED when input detects signal (for guitar)

I'm looking for a basic circuit snipping which can either turn on an LED or give a positive voltage when input signal from a guitar is detected. Basically, I have an existing circuit where an effect (...
0
votes
1answer
43 views

How to interface a passive inductance sensor output (audio-level signal) with Arduino?

Would like to interface two passive magnetic-inductance sensors output (audio-level signal) with Arduino. The sensor circuit comprises of two wire-wound sensors and has no power. It generates it's ...
0
votes
4answers
53 views

Comparator with Alternate LEDs

I want a simple comparator circuit that lights one LED when voltage is above ~1V and lights the other when below. I'm sure I'm missing a basic concept, but it seems like this circuit should have that ...
0
votes
2answers
44 views

Voltage appears on comparator input

I have made a pcb . A part of the circuit is the Schmitt trigger comparator seen above . The positive feedback resistors are chosen to give the noniverting input values from zero to 0.5 volts . ...
0
votes
2answers
52 views

Op Amp Output Voltage

I have a question about an LM741 op amp IC. I am using the op amp as an comparator (open loop with no feedback), as seen below: When the op amp output is low, the output voltage is still around 1.2v....
0
votes
1answer
80 views

Extremely simple OpAmp comparator circuit not working

I decided to make my own ADC and I tried to use the following circuit to do it. According to my knowledge, when a 5V signal is applied to the mosfet gate and then pulled to ground, the capacitor ...
0
votes
1answer
52 views

Confused about this simple Comparator Circuit Output Waveform

Below is my Circuit and Voltage Waveforms for the Comparator Circuit. My question is -- In the Highlighted area in the waveform - why is the V(CMP_OUT) not high since inp_u2 (blue) is higher than ...
0
votes
1answer
78 views

LTSpice - Voltage Comparator not working

My question is - why is CMP_OUT not going to HIGH (i.e. to 12V, P12V_IN) when INP_U1 is greater in voltage than INP_U2. I think I haven't wired the LT1011 right. Do I have to do anything with the "B" ...
1
vote
3answers
58 views

Is there a circuit that outputs high indefinitely once one high is received by the circuit? [duplicate]

Apologies if the question is worded oddly/weirdly, but specifically I have a comparator with an unstable output which I know could be fixed with hysteresis, but I would rather just have some circuit ...
0
votes
0answers
128 views

Why does my LM393N (dual comparator) ignore its inputs completely when used with an LED?

I have made the following circuit: Viusalisation (not working): https://i.stack.imgur.com/tDA85.png Circuit (working): simulate this circuit – Schematic created using CircuitLab Left to ...
0
votes
2answers
59 views

Use ADC as Analog Comparator (AttinyAVR)?

I have recently been trying to transition from Atmel's Atmega 328p avr to the newer (and much smaller) attiny416. The trouble is, the 416 only allows you to choose between two positive inputs and two ...
0
votes
2answers
113 views

How does this precision full wave rectifier work?

I am making a VU meter, and I need to rectify the audio signal for the IC comparator chip. I found this circuit in the datasheet, but I am unsure of how it works. I understand that the LF351 op amp ...
0
votes
1answer
61 views

OP amp Comparator not working any tips?

I´m running out of ideas here. I have a device that should always output a 5v signal, with a maximum tolerance of 100 mV (4.95 to 5.05 V). I´m building a "tester" device. My tester will compare the ...
1
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4answers
94 views

Clamping negative voltage on comparator input (LM393)

I need to compare a AC voltage against a reference voltage. I'm only interested in the positive part of the cycle so I need to clamp the negative part of the cycle to protect the comparator input. I ...
1
vote
1answer
74 views

How does this Current Comparator Circuit Work?

I have a quick couple of questions about this circuit: The schottky diodes are obviously for minimizing slew delay but how exactly do they do this? If the non inverting input is tied to ground and ...
0
votes
1answer
26 views

Voltage alarm with LT1017

With help of this site, I have redeveloped my voltage alarm circuit (see my previous question for the history). I started off with an 741 Opamp and it did not work as I wanted it to work (Thanks for ...
0
votes
1answer
71 views

How do I make a discrete voltage detector?

I would like to design a circuit which has outputs LOW when the voltage it is connected to is below a threshold, like 3.3V. There are some ic's you can buy to do this, but I would like to make my ...
1
vote
1answer
123 views

Inverting, single-supply comparator not working as expected

I am trying to convert an input sine wave to a square wave. The sine wave is centered at 2.5V and has an amplitude of 2V, with a frequency of 100kHz. I am looking for a hysteresis of 100mV centered ...
1
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1answer
68 views

How to use comparator functions of 74LS181?

I'm experimenting with the 74LS181 ALU (see here if you like), and it is going well, but I am unable to figure out how to use the A=B, A>B, and A<B comparator functions. The datasheet states, "...
1
vote
1answer
38 views

comparator isn't behaving as it should

simulate this circuit – Schematic created using CircuitLab The output is always outputting 5V, and I have no idea why. I have checked the inputs to the comp, I even switch them around its never ...
0
votes
1answer
112 views

COMP2 to trigger One-Pulse mode on STM32L1

I am trying to use the output of COMP2 to trigger the One-Pulse mode of a timer (in my example TIM4, but it's quite flexible if it needs to change to another timer) on the STM32L1 series. In the ...
0
votes
1answer
120 views

Need a circuit to convert 230V sine wave into 5V square wave

We have already obtained our result using transformer for our college project ,but can't find circuit to convert 230V sine wave into 5V square wave which is supplied to microcontroller. Edit: Our ...
0
votes
1answer
61 views

PWM Comparator types for Class D

I've started simulating a Class D amp, but it seems the MAX999 (I saw recommended elsewhere on this site) isn't working. Could anyone point me in the direction of why? I swapped in an LM311 which ...
0
votes
2answers
57 views

High resistance op amp

I'm making a simple op amp circuit to use it as a compactor. I connect the non-inverting point to a simple circuit and the inverting to a 3 volt dc supply. the circuit should compare the voltage at ...
-1
votes
1answer
97 views

74ls148 to 7447 to 7-segment connection. Why is it showing output 0-7 only

We have a project that requires the use of comparators, 74LS148(For Flash ADC), 74LS47 and a 7-segment digit display to show numbers 0-9. The problem is that it only shows an output of 0-7 in the ...
0
votes
3answers
90 views

Common-mode voltage outside the specified range

I'm reading the datasheet of TL331. Here a summary of the relevant specification for my question: ...
1
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0answers
37 views

How do I draw the truth table of an adder/subtractor that sets flags, and those flags are the inputs of a comparator?

How do I draw a truth table of a circuit that : starts off with a full adder/subtractor outputs the result F based on the two inputs (add if opcode is 0, subtract if opcode is 1) then output three ...
0
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2answers
104 views

CMRR of Comparators

I have been looking around for the Common mode rejection ratio value on the datasheets for comparators but there don't have one. Why is this? This ratio is crucial in terms of choosing a particular ...
2
votes
3answers
100 views

Photodiode gate circuit noise

I'm building a chronometer for high speed projectile speed measurement. Currently i'm in the process of designing the projectile detection gate. It needs to be able to detect obstructions in light for ...
0
votes
4answers
118 views

How can I modify this circuit for some hysteresis and better design?

I need to make a circuit even when the push button pushed and released very fast, the final output will stay ON at 12V for roughly a second. %10 accuracy for the timing is fine. An LED will indicate ...
1
vote
1answer
87 views

How can I use a comparator in a circuit?

I am learning about how to use Operational Amplifiers as comparators. I understand that comparators are used to compare an input signal to a reference voltage. However, I am having a hard time ...
0
votes
1answer
39 views

-Ve feedback comparator and its threshold values?

I was trying to analyse and understand the following circuit. My intention was to calculate the hysteresis of the comparator. Circuit working: For both compartor input, there will be voltage inputs ...
0
votes
2answers
37 views

Should analogue multivibrator and comparator pullup circuit have separate supplies?

I have managed to produce a design within the falstad circuit simulator for an analogue "LED chaser" using an analogue multivibrator and 3 comparators inspecting the voltage of one side of the ...
0
votes
1answer
111 views

How to pick a voltage comparator switch for a low power circuit

I am finishing up an embedded project for my vehicle and the last step is to make it automatically power off with the car. The way I detect whether the vehicle is on or not is via a battery pin, which ...
0
votes
1answer
147 views

op-amp comparator 0 or 12V output

I am trying to understand how the circuit shown below works. More specifically, I am trying to understand how the comparator outputs only 0 or 12V. (the circuit is from this paper. Without the 2.2K ...
0
votes
0answers
39 views

Voltage Divider for Comparator Threshold

I am trying to understand how the voltage on the negative pin of U2A of the below circuit is 1V/2.4V. From the author: "Threshold signal is 0V/5V but it changes ...
-1
votes
1answer
60 views

How to use two USB power banks

I want to use two USB power banks for a camera to get longer battery life. Was thinking when the first one is drained, I would have a relay switching over to the other bank, using a comparator for ...
0
votes
0answers
223 views

Using a comparator in tinkerCAD circuits

For anyone familiar with the TinkerCAD circuit design tool I am trying to create a simple circuit for an 'LED chaser' pattern (this is what I have seen it called elsewhere). In order to create this ...
2
votes
1answer
80 views

LM339 Incorrect Behaviour for Two Elements

I am designing a monitoring circuit for a battery powered device that is charged from a solar panel. The circuit uses an LM339 to indicate the input voltages via two dual colour LEDs, one for the ...
2
votes
2answers
225 views

High-speed Infrared UART link with photodiode

I need short-distance (about few centimeters) wireless IR UART link with 250k+ baud. I tried to use phototransistor (assume Q1 is phototransistor). Q3 is used to prevent inverting signal. simulate ...