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

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Photon counting circuit

Hello I am a college student working on photon counting circuit using Silicon Photomultiplier(SiPM) similar to one described in the figure below: Stage 0: Signal from SiPM Description: This is an ...
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2answers
33 views

How are the circuits and design considerations for opamps and comparators different, at an integrated transistor level?

I've designed various transconductance and operational amplifiers in CMOS technologies in the past. I've also worked with clocked latching comparators. However, I've yet to design an asynchronous ...
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28 views

Making an LM393-based adjustable voltage buck converter

I recently saw this circuit for an LM393-based adjustable constant-current buck converter intended for driving 1W or 3W LEDS and decided to build it. It worked very well, and I was wondering if it ...
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1answer
54 views

Designing an High Amperage, Low Voltage AC Voltage “Breaker” for Model Train

I’m trying to build a simple circuit that acts as a "voltage breaker" – meaning that if a voltage exceeds a certain threshold, analogous to a (current) circuit breaker it will open a circuit. There ...
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2answers
28 views

Open Collector Comparator for Voltage Glitch Detection

I recently ran a round of PCBs which included an experimental circuit to detect short glitches in my input voltages. I attached the schematic for reference: The intent is that C29, in parallel with ...
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1answer
56 views

LM358 (as comparator) output voltage less than supply voltage

I've setup a simple circuit with an LM358 configured as a comparator (the ground rail and supply connections are off screen). Schematic: Breadboard: (in case I wired something wrong) Measured ...
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36 views

How the relationship between input and output is derived in a comparator?

In the slide 6 of the page about propagation delay of a comparator, the time relationship between input and output is as below. However, I am not sure how the function between input and output voltage ...
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1answer
48 views

Having problems with a window comparator

I'm trying to set up a comparator circuit that only supplies voltage to a connected LED if the voltage provided falls within an expected range, but I'm having some problems. For testing, I have it ...
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1answer
45 views

Safety considerations when using LED and a comparator

I want to make a simple circuit, it uses two comparators to drive two LEDs, it should turn the LED (green) if the voltage is higher than let's say +2.5V. If is lower then turn the first one off and on ...
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30 views

PIC 12f683 comparator reference voltage setup

I'm currently trying to set up my PIC 12f683 to run an interrupt when receiving a voltage over 0.2V from an amplified microphone input using the comparator module. Microphone aside, I have lined up a ...
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2answers
92 views

Why does the ATTiny84 have both an analog comparator and an ADC?

I have been reading through the datasheet for the ATTiny84A, and noticed that it has both an analog comparator and the ability to use its ADC in unipolar or bipolar differential mode. From what I can ...
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46 views

Op-Amp inputs are sinking too much current in comparator mode

So I basically designed a circuit to limit the current flowing through a 250 ohm resistor by shutting down the current path using a mosfet when current goes above 30 ma: R1 is the 250 ohm resistor ...
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83 views

A naive solar panel maximum power point control circuit

I am fooling around with a solar panel, just to try stuff and learn in the process (not trying to produce something I would actually use). Its placement is very far from optimal - vertically behind ...
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2answers
72 views

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
41 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
62 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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57 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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71 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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38 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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59 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
65 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
51 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
159 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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47 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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65 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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40 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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23 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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72 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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75 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
53 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
445 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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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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58 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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116 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
63 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
41 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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63 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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83 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
54 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
64 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
47 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
325 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
119 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
88 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
70 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
60 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. ...
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1answer
118 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 ...