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

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Battery as reference voltage

I am fooling around with a solar panel and I am trying to make a circuit, which would monitor its voltage and eventually switch the load on and off. The thing is, I don't have a good "reference" ...
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2answers
36 views

Am I able to make a comparator on optocoupler?

Initially I'm trying to make over current protection scheme. So if the R2 current (and therefore R2 + D1 voltage) will go higher than some certain level I should have a signal to break the circuit. ...
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2answers
51 views

Using a LM311n in a class D amplifier as comparator

I'm making a class D amplifier as a school project, and we are currently at a stage where we simply need to add the comparator. But the comparator (LM311n) does not seem to run as intended. My ...
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4answers
78 views

Purpose of Resistor - comparator

I am studying this time delay circuit and am curious to know the purpose of the 4.7kΩ resistor. As I see it, it has no purpose. I've built and tested this circuit with and without it and see no ...
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0answers
28 views

8 bit magnitude comparator using IC 7485

When making an 8 bit magnitude comparator by cascading two 7485 ICs, why do we connect the A=B pin to "HIGH" while A>B and A to "LOW" ? A comparator will first compare the MSBs before the LSBs. ...
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1answer
55 views

Help comparator circuit for this PWM signal inverter

I have 2 signal (signal on the left) and how to combine those 2 signal into the signal on the right, I have try using lm 741 op amp, but unfortunately the output signal is different from the ...
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1answer
33 views

Comparator input below V-

I am searching for a way to use a comparator with possible negative voltage on its inputs. My thoughts and attempts so far: Op amps and comparators with V+, V- and GND: the circuit utilizes a ...
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0answers
56 views

Flickering pulses from a comparator

Above is the circuit converting sines to pulses. Please click on it to enlarge the image. Input signal is a sine from an alternator 4Hz 2V up to 17Hz 12.5V. The circuit is implemented on a ...
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2answers
61 views

Comparator/NAND/NOR ADC not working properly

simulate this circuit – Schematic created using CircuitLab I was trying to recreate the following ADC (using comparators or NAND/NOR logic elements) circuit to control a 74HC4514 with a ...
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1answer
49 views

How to detect a signal if it is greater than VDD or smaller than 0?

I need to detect a signal if it is greater than VDD or smaller than 0. I can't use comparator because the input signal is outside of common-mode input range and I have only one power supply VDD. Is ...
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2answers
149 views

Can a mosfet on if there is no current flows through it?

I am reading about hysteresis comparator here and wondering if a mosfet can be on if vgs is larger than threshold voltage but there is no current flow through it (vds is zero), As you can see in the ...
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1answer
45 views

Comparator (lm2903) help

I have a 9v source driving a comparator with a 5v source that is pulsing with 1s intervals, and a 2.5v constant source. with a pull up resistor of 10K to get make my vout 9v when my pulsing source is ...
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63 views

Comparator help (Lm2903N)

I am using a LM2903N to learn about comparators. I am powering the unit with a 9v battery and connecting to the (+) 5v and the (-) 2.5v. However, when I check the output the resulting voltage is 0v. ...
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0answers
26 views

Spice modeling of a comparator using zero-pole transfer function

I'm designing an open-loop comparator for an analog IC. I've followed the design procedure included in the "CMOS analog circuit design" by Holberg and Allen. I've established the required gain and ...
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0answers
21 views

Conventional dynamic comparator

Here (page 2) is a conventional dynamic comparator. I am wondering about function of M3 and M4 here. Could anyone explain that?
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0answers
53 views

4-bit Comparator Verilog Code

I need to create structural verliog code to make a four bit comparator (out of four behavioral-coded one bit comparators). But I've only gotten my greater than output to work. I'm using this circuit ...
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1answer
58 views

Hysteresis calculation for “open-collector output comparator” with a pull-up resistor

Standard comparators such as LM2903 and LM311 have open collector outputs. I see many times the output of these comparators are tied to Vcc by a pull-up resistor (e.g. in a Schmitt trigger case). ...
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2answers
73 views

Comparator Inputs Approaching the Same Voltage

Please excuse any mistakes or blatant errors, I am a beginner. This circuit is meant to have the op-amp function as a comparator, and produce peaks on the output that I want read by a microcontroller. ...
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2answers
44 views

Voltage divider or zener clamp when coupling a comparator output signal to a DAQ?

As shown in above figures above, a comparator is outputting 16V pulse signal when it is ON. For some reason I want to lower this voltage around 8V pulse. In Config 1, it is coupled to a voltage ...
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3answers
430 views

A question about positive feedback resistor in a Schmitt trigger

In many tutorials when explaining hysteresis what I read that when the output is high R3 becomes in parallel with R1; and when the output is low R3 becomes in parallel with R2. Above is a depiction ...
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1answer
29 views

Voltage reference for comparator

I need reference for comparator and considering option between using one made from voltage divider and the one from precision reference. Basically, if i were to use voltage divider, it will be simple ...
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0answers
52 views

Need suggestion about voltage divider values and the place of the RC filter in an opAmp circuit?

I'm trying to finalize this circuit above before the test day. This is the last configuration after updates. I started to ask about another issue about this circuit, but with the suggestions of ...
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5answers
104 views

Op-amp comparator

I am modeling a comparator as follows: simulate this circuit – Schematic created using CircuitLab So I want the following: if V15=0, then the output should be 0. But if V15=5, then it ...
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3answers
79 views

Passing greater of 2 voltages using 5V signal

I need to output the larger of two voltages (Va, Vb) (both of which could be in a range 0-30V), but drive the circuit using a 5V supply. A simple solution (using op-amps, FETs) is needed. I have ...
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2answers
55 views

Circuit understanding about the amplifier with a MG811 CO2 sensor

I am working on a project similar to this post. For the circuit diagram on that post, what are the function and working principle of the upper amplifier? I know that the lower amplifier is used to ...
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1answer
62 views

Conditional Voltage output

I apologize if this is extremely simple, but I am trying to design this: I input 2 voltages, one is 12 V and the other is on the order of .5V. I want to know if there is something I can set up that ...
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1answer
38 views

Output State of comparator circuit for AC signal when open?

I am trying to design a circuit which would interface AC signals from pick-up coils. Below is the circuit. R4, R3 are for DC bias, and R2 is for feeding that bias to inverting input of the OP amp. ...
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2answers
57 views

Does Analog Comparator mean Voltage Comparator?

I was asked to define what an Analog Comparator was. After doing research, it seems to me that Analog Comparator is the same as a Voltage Comparator. Is this true?
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1answer
80 views

Pull-up resistor causing unintentional voltage divider?

I'm trying to use the output of a comparator as the input of a schmitt trigger built with positive feedback on another comparator. Both have open collector outputs. When the two are not connected, ...
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0answers
51 views

Schmitt trigger application

I have a sine input signal in range from -0.2V to +3.3V. I would like to detect zero crossing with comparator in Schmitt trigger wiring with hysteresis between -0.1 and +0.1V. Is this circuit possible ...
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1answer
63 views

Two different voltage input to be monitored by microcontroller

I just wanted to make a detailed circuit design that I can use in my project. a design that can supplement on the OR gate Given the two different voltage input, I need an output of a voltage around ...
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1answer
45 views

Comparator with latch as trigger

I was hoping to use a Linear Comparator with a latch such as LT1016 as a trigger for the Register output clock for a 74HC590. The 74HC590 is going to be cascaded with it's RCO going to several more ...
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3answers
206 views

LM358 as a comparator output problem

I've got an LM358 based ground fault detector circuit that I've recently revised, and the revision broke it, so far as I can tell. To make a long story short(er), what it amounts to is using one of ...
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1answer
104 views

LM311 Circuit only works when probe is attached

I'm trying to put together a circuit that takes a signal from a sensor, cuts out the negative side, compares it to a reference voltage and outputs a digital 1 when above the reference voltage. That ...
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1answer
82 views

Power Gating a Comparator

I am using a comparator (TS3021) as a zero crossing detector (ZCD). The ZCD toggles its output based on the zero crossings of a sine wave generated across a transformer coil. One end of the coil is ...
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1answer
66 views

Is this something a P.L.C. would be able to do?

I wish to replace the zener diodes with a programmable chip, so that I can program the chip to do exactly what the zener diodes do in this circuit. This will then make the circuit universal to all my ...
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1answer
58 views

Measure Voltage (Divide) on a current source

I need to use a constant current source 20mA, the current flows through multiple diodes and resistors which are in series. The resistor value can vary from 0 to 1.6k and also a possibility of Open. ...
2
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1answer
114 views

555 Input Impedance

I'm building an audio circuit and need a comparator. I've explored using an op amp for this purpose but my TL072 doesn't seem to have a high enough slew rate which resulted in latency. Instead, I've ...
3
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1answer
52 views

A question on transforming a non-inverting comparator to an inverting one?

Here is the schematics for the question: I was using the LM311 as a non-inverting comparator without problem. It works fine and here is the output below: But if I use it as an inverting ...
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1answer
33 views

Delay ERROR - RC Circuit

I have designed this circuit to measure the current on the load and the comparator trips when the current of 1.2 A exceeds for 2ms.This works fine with simulation.When I build this circuit,my circuit ...
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1answer
65 views

Comparator and 7 segment display

I am trying to make a 7 segment display that displays the symbol <, > or = depending if a > b or a=b or a < b by using the output of a comparator(7 outputs from the comparator according to the ...
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4answers
228 views

Comparator Latch circuit

I need a VERY simple latching circuit using comparator that will simply be off until a signal hits it (can be either + or -, I have no preference) and the circuit will remain on until I reset it.
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1answer
85 views

Low level sine to pulse converter with sharp rising-edges

I have two circuit simulations: Circuit1 and Circuit2 which are shown in above schematics. For the sake of simplicity I drew them in the same schematics. They share the same 12V voltage source and ...
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2answers
56 views

High side current indicator/

simulate this circuit – Schematic created using CircuitLab Hi! I am in need to make a high-side current monitor for detecting whether load (R1) is present or not. As currents running ...
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2answers
105 views

Output current sourced/sunk by comparator

I am using the LM139 comparator chip. Now, I understand that the output of the comparators,or for that matter op amps are open drain/collector. SO they can only sink current and not source it per se. ...
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3answers
63 views

inverting comp behaving strange

I am using an LT1716 comparator in the inverting mode. So, I am simulating it in LTSpice. I understand that the Vout is Vcc when Vin,at the inv terminal is less than Vref at the non inv terminal and ...
2
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1answer
76 views

How to detect end of Capacitor Pre-charge

A common problem with batteries and loads connected to them is that the load often has substantial capacitors which needs managing . When the battery is connected to the load by closing a ...
0
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2answers
135 views

How to tell when an LM334 is limiting the current?

I have an LM334 based constant current source configured to supply a max of 1 mA. The load has a variable impedance. My goal is to make an alarm of sorts when that impedance exceeds a threshold, and ...
4
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1answer
213 views

Why add resistor on comparator input?

I'm studying the schematic for the constant current/constant voltage (CC/CV) indicator on an Agilent E3610A: My question is: What purpose is served by the 10kΩ resistor (R26, R16) on the ...
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1answer
44 views

Comparator power dissipation

I want to calculate the LM339 comparator power efficiency, so I thought the best way is to calculate the output RMS power and the Power dissipation and the quiescent(DC) power then will get the input ...