Questions tagged [comparator]

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

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Selecting power for the comparator IC from multiple power sources

I've designed a simple circuit to select the power source automatically, and I'm not sure what the best practice is to power the comparator (U1) only if the +12V0_B power is connected. First things ...
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Dual brushed motors digital controller works on only one side

I'm actually developing a way to control, digitally, the speed of brushed motors with a Raspberry Pi. To do so, I use the following diagram where: The raspberry controls the shift registers (purple) ...
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How can I monitor the CC lines on USB-C port?

I need to develop a device which has a USB-C port. This port has two purposes: One can connect a USB charger to charge the battery of the device One can connect USB headphones to listen to some music ...
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Identifying nodes with multiple ground symbols/two dots in the same apparent node

I'm reading the Art of Electronics. Figure 1.18 is the circuit given below. I'm learning about nodal analysis, and have two questions. First, this image contains three "ground" symbols. ...
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Output level of LM311 comparator

I am simulating the circuit above in LT Spice, where a LM311 (a LT1011 is simulated, but should be largely equivalent) is used to transform a (noisy) sine wave signal into a square wave. Value of R5 ...
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Schmitt trigger Upper and Lower Threshold voltages

I speak with reference to this (Electrical4u - blog tutorial) and this (All about electronics - video tutorial) on the Schmitt trigger. From what I have understood, in the non-inverting schmitt ...
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Need help figuring out why my comparators aren't working

I got a few quad comparator ICs (uA339PC) and after trying them out and even going online and following a few schematics and videos, they just don't seem to work. I tried out 3 of them and I got the ...
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Over Current/Short Circuit Protection Using op-amp and MOSFET

I wanted a circuit to limit the current to say 4A, and found this but it doesn't work in the Proteus simulator. What's wrong with this circuit? anyways to improve it? here is my expectation of the ...
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LM393 soldering station

I found on the internet and I built the schematic below. Then I tested with the oscilloscope and I found that when going from on to off and from off to on then some unwanted transitions appear on the ...
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4 answers
385 views

Can I replace an LM741 op amp with an AD620 op amp in my circuit? [closed]

I have a voltage comparator circuit (shown below.) Can I replace the opamp with an AD620 op amp? My lab has mostly AD620 op amps.
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Thermal Protection - NTC + Comparator + Hysteresis

I am looking to implement a temperature protection circuit using an NTC thermistor and a comparator. Was thinking of using a hysteresis design I found in a manual by TI - Do you think that's a good ...
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2 votes
3 answers
114 views

Compare two voltages and output the higher of those two

From the LM35 output I get from 0V to 1.5V. There are 4 outputs like this. How can I compare these values without using a micro-controller and forward the highest value of those 4. I can't connect the ...
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PFET switch design not behaving as expected

I'm trying to use a P-Channel MOSFET as a shutdown switch for a logic circuit. I have what I want working in isolation, it looks like this: These are the voltage curves: As you can see, the initial ...
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3 votes
1 answer
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LTSpice simulation with multiple comparators causing problems

I'm trying to build a circuit that limits the current flowing to the load at a specific level. To do this, I'm using a current sensing IC (INA138) and comparators to provide the necessary logic. ...
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1 answer
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Comparator vs Error amplifier vs OP-amp [closed]

Could you do me a favor? It is my first time to use "StackExchange". I wonder the different point of these three components. Comparator vs Error amplifier vs Op-amp (and OTA) As I found they ...
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Check if two voltages (with different grounds) are within 0.5 V of each other

I have designed the following circuit that should be able to detect if two voltages Bus Bar VBAT and VBAT that are referenced to Bus Bar GND and GND, respectively, are within 0.5 V of each other. On ...
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1 vote
3 answers
101 views

Shunt voltage direction circuit [closed]

I need to know which terminal of a shunt is higher, ie whether I'm charging or discharging my 12v battery bank. The voltage difference is very small (max 74mv) since the current flowing may be tiny, ...
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Mux Auto Addressing Circuit

I am trying to build a circuit that will allow multiple (up to 4) muxes on the same I2C line. I am trying to get their addresses to increment with each new board connected. (Lines A0 to A2). Here is ...
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Help Deciphering Encoder Pin-Out After Differential Comparator Circuit

I am trying to interface a translation stage with a different non-proprietary motion controller. Trinamic's TMC4671 seemed appealing due to cost and functionality, especially the evaluation kit. ...
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-2 votes
1 answer
70 views

How can I use a slide switch to reverse polarity of this comparator circuit?

This circuit is a simple photo-transistor switch with 2 independent threshold potentiometers. I've placed a switch to alter functionality of the comparator. Mode 1: Always ON. I simply connect the ...
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Problem replicating voltage regulator circuit in LTSpice

I'm new to voltage regulation circuits and have a circuit from https://www.ti.com/lit/an/snoaa20/snoaa20.pdf that I've used as inspiration: My circuit in LTSpice is below: The Zener diode is 7.5V. ...
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Help in understanding how this over-voltage regulator works

I found a circuit on the internet that's using a comparator to solve a similar problem to one I'm hoping to solve (voltage regulation). This is the circuit: (it's from https://www.ti.com/lit/an/...
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1 answer
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Comparator switching randomly

I cut a toroid in half, one half has unknown number of turns (50~80) which are fed to LM339 comparator which is pulled high by 500R to 3.3 V. simulate this circuit – Schematic created using ...
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-1 votes
2 answers
65 views

LM393 window comparator not providing output when used with rail voltage

I have a pretty straightforward window comparator circuit using a 393 dual op amp. The below schematic simulates perfectly and goes HIGH to the 12V rail and LOW to the ground rail during sim. But the ...
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2 answers
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Undervoltage Lockout TLV7031

I try to implement an undervoltage lockout trigger, when the supply voltage falls below a threshold voltage. The trigger itself should activate a gate driver, when there is enough voltage and below ...
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1 vote
2 answers
101 views

Using two op-amps to measure the current in a predefined window

I've been trying to use an op-amp to measure the current and then use two op-amps as a comparator to detect the whether the measured current is within a window. The circuit defines the upper and lower ...
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-2 votes
1 answer
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Design safety relay with OpAmp

I intend to use a safety relay for my project, however I found industrial safety relay mostly work with 24 VCC and is very big, so I decided to make a safety relay based on my specifications. What I ...
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1 answer
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Zero Comparator with Hysteresis NOT working? [closed]

I tried to make a zero comparator with hysteresis but apparently it does not work. Any suggestions? My conditions of making the output to zero is the Hysteresis voltage level at 50mV to 2V. See the ...
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2 answers
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LM139AD Comparator Negative Inputs

I am wondering if the LM139AD comparator from TI can tolerate negative voltages at its inputs. I see that it can operate from a dual supply and that a supply rail can be negative? Is the same true for ...
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1 answer
31 views

Using a 1-bit input to signal signed vs. unsigned comparison (in CircuitVerse)

Disclaimer, I'm a total electronics/circuit noob so sorry if this is really simple! But I've just built a 4-bit less-than comparator in CircuitVerse (outputs whether A < B), and I want to use a 1-...
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PWM output for DAC and using DAC as reference voltage

I would like to use a DAC as a programmable reference voltage for a window comparator. The input of the DAC would be the Arduino's PWM output. Can I connect the Arduino's PWM output directly to the ...
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ATmega analog comparator generates spurious interrupts

I'm experimenting with the comparator inside a ATmega328 to see if it can be used for zero detection of a DC 2.5V superimposed AC signal monitored on one of the ADC inputs. I use the code as shown ...
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More current in non-inverter comparator hysteresis using a photoresistor

I'm doing a small circuit where I need automatic LED's to turn ON in a low light environment. So I decided to use a photoresistor (more light less resistance) connected to a non-inverter hysteresis ...
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2 votes
0 answers
91 views

How to keep the reference voltage constant for comparator?

I want to build a circuit with a comparator, but the reference voltage is changing (CH3-purple) as seen in the oscilloscope image. I used the TL431 as in the image to keep the reference voltage ...
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2 answers
72 views

Simple circuit that would close the circuit if it reached a higher voltage to a lower voltage, but not close the circuit from low voltage to high Volt

I'm currently trying to operate a supercapacitor that'd be charged up using footstep to energy system, then once the super caps are charged, it's energy is used somewhere to be stored via MPPT module. ...
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0 answers
69 views

High-voltage chassis voltage detector using a comparator

I am planning on using a comparator together with a resistor divider network to detect when a chassis voltage is present. Please refer to the previous post here for more info if needed. So S1 is used ...
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Comparator TLV3201 Output never goes high

I've put together the circuit from the TI document Comparator with Hysteresis Reference Design using the same reference voltage to the noninverting input (Vth 2.3V - 2.7V). The Inverting input is ...
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-1 votes
4 answers
186 views

Why is the transistor in this dimming circuit getting very hot?

This is a fairly simple dimming circuit using a dual opamp (IC1) as a comparator to control the brightening and dimming of a light bulb. The switch (pin 2 IC1a) is a contact connection to ground. ...
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0 votes
1 answer
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Can you use dynamic comparator in place of static comparator and vice versa?

According to the book, there are two types of comparators, static comparator and dynamic comparator. The dynamic comparator has clock. So can you use dynamic comparator in place of static comparator ...
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1 answer
113 views

How does this circuit act as a half wave rectifier?

I'm having trouble to understand how this circuit operates exactly. The op amp is an LM339 from ST (datasheet link). The circuit in question is as follows: The op amp should be a comparator, but the ...
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1 vote
1 answer
75 views

333mV Current transducer - how to read it and protect the Atmega328p input

i have this CT current transducer: it outputs 333mV at 5A full scale. I'm planning to use it in my house/office in order to detect if a load is switched on or off, but i'm worried about how i can ...
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SCT-013-010 - Pulse on current threshold

I have this current sensor, it has a measuring range of 0-20A and outputs 0-1V. I need to create a circuit that uses this current sensor, and trimming a current threshold (using a trimmer) the circuit ...
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0 votes
2 answers
76 views

How do we justify small signal analysis of comparator while we know that the biasing condition for the input devices are different?

During the real operation of comparator, the input baseline is lower than the threshold voltage. How do we justify small signal analysis of comparator while we know that the biasing condition for the ...
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51 views

Photodiode pulse detect system

We have a laser signal detection system as shown in the figure below. In this system, we want to detect the incoming laser pulse. The MCU will detect the incoming pulse and perform its operations ...
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AC tachogenerator frequency sensing using LM393 comparator

I'm currently recycling an old washing machine brushed universal 230 V AC motor which has an attached tacho generator, and I'm building a closed loop controller board for it. I'm up to the point where ...
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2 answers
65 views

Fixed-direction voltage translators (level shifters) input voltages

I have a circuit that outputs a digital signal to an FPGA on an XEM6310 board. To digitize the signal, a comparator is used with a reference/threshold voltage of +12 V, with its positive rail tied to +...
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1 answer
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How to understand the next values of a comparator inverting with hysteresis (Schmitt Trigger)?

I have my test graded and I'm curious about a question, since I think it's badly graded and I may need to request a revision. I have been told there is a comparator inverter with hysteresis so \$|V_{...
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4 votes
1 answer
172 views

Why does the comparator burn in this oscillator circuit?

I have the following circuit: Power filtering: The 330 μH chip inductor has about 10 Ω series resistance. I scoped the powerup to 5 V and the overshoot even with no load was minimal (maybe 300 mV). ...
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Finding Diff Eqs for Variable Square Wave Oscillator of Theremin

For a project, I built a theremin using an LM311N as the basis for my fixed and variable oscillators. I wanted to find the period of the variable oscillator by finding the systems of diff eqs ...
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2 votes
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209 views

LM339 LED voltage indicator behaving opposite of expected

I have built the attached circuit and am pretty confident it is correct with no short circuits. When it's powered up with a 9V battery, all 4 LEDs light up with no input voltage. As the input voltage ...
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