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

learn more… | top users | synonyms

0
votes
1answer
89 views

Voltage divider before the input of an LM324N used as a comparator

simulate this circuit – Schematic created using CircuitLab I am designing a driving system to control some servomotors, and since my microcontroller can not drive enough current, I had thought ...
0
votes
1answer
57 views

Comparator Question (and more general question)

I have been fascinated with electronics my whole life and read many books on it, but only recently have I began to really tinker, and I have often been befuddled by many salient details that are ...
3
votes
1answer
85 views

Basic Comparator Question

I am currently reading Practical Electronics for inventors and am having a bit of trouble understanding the output of the following circuit: Now as I understand, if Vin>Vref then the transistor ...
0
votes
2answers
41 views

Sensor Module misbehaving when connected to a voltage divider

I am using this sensor module with Raspberry Pi 3 http://www.sunrom.com/p/optical-slot-sensor Since this is a 5V sensor, I connected a Voltage Divider circuit. But the sensor misbehaved. The output ...
0
votes
1answer
49 views

Creating a simple voltage regulator for medium currents

Question, as fast as possible: Would this circuit regulate poorly-regulated +12VDC effectively? I am an electronics level zero, so please bear with me. Please let me know if you would me to clarify ...
1
vote
2answers
168 views

comparator sending out vcc value

I am having trouble using an comparator, the LM319N. I am trying to get a 0.5V to -0.5V signal to raise to a 3.3V - 0V signal so i can read it using gpio pins on my micro controller. I tried a few ...
0
votes
1answer
94 views

LM393N output doesn't behave as expected

I am currently working with the LM393N and am inconsistently getting a high output when it should be low. Below is a schematic showing the inputs and outputs of the IC. VCC is coming from a "12V" ...
-1
votes
1answer
49 views

Choosing differential receiver IC?

I have a differential signal A which I would like to convert to LVTTL output X as follows: X = 1 iff A+ > A- + 50 mV. That is to say, X is '1' only when A+ is more than 50 mV greater than A-. ...
0
votes
1answer
91 views

Vout of differential amplifier as Vref of comparator

simulate this circuit – Schematic created using CircuitLab I am a beginner at circuit design, and I am having trouble using the Vout of differential amplifier as Vref of comparator. The other ...
0
votes
1answer
87 views

Issues with a timing circuit using a comparator and RC

Above is a comparator circuit which employs RC time constant to control the ON time of the output(please left-click to enlarge the image). Red plot belongs to the momentary-switch voltage versus time, ...
0
votes
0answers
49 views

risks of going with a very low reference voltage for a comparator

Objective Digitization of pulses of width 10ns-150ns repeating at a rate of ...
1
vote
1answer
44 views

Need for inverter chain to decrease rise and fall time in a comparator

I was designing a MOS comparator for my laboratory and I could not understand how an inverter chain helps in increases the slew rate across the load capacitor. And why an inverter chain ? why cant a ...
0
votes
1answer
109 views

Photon counting circuit

Hello I am a college student working on photon counting circuit using Silicon Photomultiplier(SiPM). Stage 0: Signal from SiPM Description: This is an image captured from oscilloscope with the time ...
3
votes
2answers
42 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 ...
0
votes
1answer
57 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 ...
1
vote
1answer
59 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 ...
2
votes
2answers
52 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 ...
1
vote
1answer
71 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 ...
0
votes
1answer
39 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 ...
0
votes
1answer
59 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 ...
0
votes
1answer
47 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 ...
0
votes
0answers
43 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 ...
2
votes
2answers
105 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 ...
0
votes
2answers
50 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 ...
6
votes
1answer
103 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 ...
0
votes
2answers
76 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" ...
0
votes
2answers
53 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. I'...
1
vote
2answers
88 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 ...
1
vote
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 ...
0
votes
0answers
115 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. ...
0
votes
1answer
93 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 signal(...
0
votes
1answer
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 ...
0
votes
0answers
61 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 breadboard....
0
votes
2answers
66 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 0-5V ...
0
votes
1answer
53 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 ...
5
votes
2answers
207 views

Can a MOSFET be on if there is no current flowing through it?

I am reading about hysteresis comparator here and wondering if a MOSFET can be on if \$V_{gs}\$ is larger than threshold voltage but there is no current flow through it (\$V_{ds}\$ is zero), As you ...
0
votes
1answer
48 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 ...
0
votes
2answers
69 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. ...
0
votes
0answers
61 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 ...
4
votes
1answer
103 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). ...
1
vote
2answers
78 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. ...
1
vote
2answers
63 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 ...
3
votes
3answers
457 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 of ...
0
votes
1answer
31 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 ...
0
votes
0answers
64 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 others ...
1
vote
5answers
130 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 ...
1
vote
3answers
83 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 ...
-2
votes
2answers
76 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 ...
1
vote
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 ...
0
votes
1answer
47 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. ...