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64 views

Understanding this comparator circuit for AC voltage protection

The circuit shown below is taken from this whole design. I understand the main idea. They want to measure some voltage condition and trigger something else with the comparator. R39 and C38 form a low ...
0
votes
1answer
43 views

Abuse TS339 comparator channel as a voltage multiplier

I have multiple free channels of a TS339 amplifier remaining and would like to use one of them to multiply voltages like this: simulate this circuit – Schematic created using CircuitLab Now it'...
0
votes
1answer
65 views

Comparator Undesired Behavior

The following circuit is a comparator, which compares input square signal at non-inverting pin with fixed reference voltage at inverting pin of integrated comparator circuit LM393 (\$R\$ is collector ...
0
votes
1answer
50 views

Which Comparator could match this electronic circuit?

Below is a schematic of a current regulator using a comparator IC2. The board is from an XP-605 ELENCO bench top adjustable power supply. Searching the WEB was unsuccessful in finding any original ...
0
votes
3answers
60 views

When to put resistor on comparator input

I am using a open-collector output comparator (ROHM BA8391G) to enable a voltage regulator when Vin > 12V is detected (comparator output will be HIGH when Vin > 12VDC). Vin can be in the range of 12-...
3
votes
1answer
84 views

What is this Venn-Diagram-looking symbol?

So I am looking at the datasheet for the LTC4416, and there is this Venn-diagram symbol after the op-amp, but I don't think it is supposed to be an inverter. It is also used for these currents, but ...
0
votes
1answer
53 views

DC Voltage Comparator

I'm looking to build a simple DC voltage comparison circuit that outputs a logic high or low depending on the input, say when it rises above 2V. From my admittedly rudimentary understanding of op-...
0
votes
0answers
24 views

two stage open loop comparator question

I am trying to understand the operation of a two stage open loop comparator. simulate this circuit – Schematic created using CircuitLab What is shown is the output stage, current-sink inverter....
1
vote
2answers
64 views

Comparator as a current detector

I'm looking for a simple circuit that uses only a comparator (or an opamp) to detect the presence of a small current through a high-side current resistor. The idea is for a microcontroller input to go ...
0
votes
1answer
25 views

How to simulate a comparator in Simetrix/SIMPLIS

I am trying to generate a square wave using a comparator and I am trying to simulate the whole circuit using the software Simetrix/SIMPLIS. This is the circuit I am using: The first part uses a ...
0
votes
1answer
49 views

sine wave to square wave using LT1017

I am trying to convert sine wave of 50 Hz and 10 mV to square wave of 10 mV of positive side only. I used the following circuit. But the square wave has higher voltage compare to my requirement. ...
0
votes
0answers
38 views

how to power up a subtractor using a window comparator?

I'm making a circuit that will detect whether a voltage(V1)is in between the range 1-2 V. If so I want to switch ON a subtractor and output V1 - 1 V. I initially thought of connecting the output of ...
1
vote
0answers
92 views

Comparing sine wave and triangular for spwm using comparator

i am trying to generate sinusoidal PWM by comparing sine and triangular wave. First i just tried to compare sine wave with reference voltage in order to check the working of op-amp. I get a problem ...
6
votes
5answers
2k views

Operational amplifier as a comparator at high frequency

I am trying to generate a sinusoidal PWM signal using analog circuits. I want to compare my sine wave and triangular wave using an operational amplifier (LM741) which has a rise time of 0.3 µs ...
3
votes
1answer
82 views

How to use a low current signal to activate my circuit

I'm building a small circuit that needs to be powered by another device. I will power my own circuit from the already existing devices battery. I need to be able to shutdown/power-up my circuit ...
10
votes
2answers
549 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
votes
1answer
77 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. ...
-1
votes
1answer
94 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
votes
1answer
121 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 ...
0
votes
2answers
67 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 ...
0
votes
2answers
63 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
173 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
59 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
1answer
102 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
vote
1answer
111 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 ...
1
vote
1answer
162 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 ...
0
votes
2answers
59 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
vote
1answer
117 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
163 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
201 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 ...
2
votes
2answers
330 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 ...
4
votes
4answers
452 views

Pick largest of several voltages with analogue comparators

This is not an XY problem. I have already decided that the best way to handle the actual application is to use a multiplexer and ADC/MCU to measure all the voltages. However, I am always keen to find ...
0
votes
2answers
101 views

OpAmp Comparator Circuit Design for High/Low voltage measurement

I am new to this. I want to make a circuit to measure the voltage from (0 ~12 V), which can have 2 op-amps as comparator to give the output positive, when the voltage goes from 8 V to 12 V and give ...
1
vote
1answer
109 views

MCP6548 comparator circuit isn't working

Hey guys back at it again, sorry. I am using a standard MCP6548 Comparator to finish the first stage of my project. simulate this circuit – Schematic created using CircuitLab OP's schematic....
1
vote
2answers
126 views

What should be the voltage divider resisor values in units?

I'm trying to build a circuit that lights up a LED when a battery connected to it is full charged. I found LM358 lying around so I plan to use it as a comparator. I want a 3.7v using a voltage divider,...
1
vote
1answer
193 views

LM311P op-amp strange behavior in comparator mode

I'm trying to build a schematic which will turn on a relay in case motorbike battery voltage will reach some level. I've ended up with the following schematic. simulate this circuit – Schematic ...
1
vote
1answer
268 views

Arduino inductance meter using op-amp as comparator?

I want to create an Inductance meter with an arduino nano, for that I follow that link whose theory convinced me : tutorial (The Diode on schematic remove analog negative voltage, Edit: I have ...
0
votes
1answer
375 views

Problem with output swing in LM358

simulate this circuit – Schematic created using CircuitLab I am working on a battery charger with indicator. I am using a LM358 to compare the voltage of my battery with a reference voltage of ...
0
votes
2answers
101 views

How can I modify this opamp circuit's logic

I need a system where it follows the input voltage below a set threshold voltage, and it outputs a set voltage above the threshold voltage. Below is my attempt: The circuit shown can output a set ...
1
vote
1answer
283 views

Problems while using op-amp as a comparator on a single supply

Here's my circuit: . Application: The circuit is for ground fault detection. When a fault current of 20mA flows through the primary of the current transformer (1:660), it generates a current of ~30uA ...
4
votes
2answers
730 views

Saturation problem of comparator [duplicate]

I am trying to design a comparator using a 741 IC, with a single supply of 12V. I have set the reference to 2V and I require the output to toggle between 12V to 0V. but the problem I am facing is the ...
2
votes
1answer
306 views

Capacitor weird behavior

I have hooked up the following circuit: Also, is there any possibility to create a link for the schematic? After posting it I realized it´s too small to be seen but I don´t know how to fix it. ...
2
votes
2answers
699 views

How can there even be an input voltage on a long-tailed pair?

Assuming the following: The voltage across the base-emitter junction of a BJT is constant in forward-active and saturation mode The BJTs in a long-tailed pair are normally forward-active or saturated ...
0
votes
1answer
422 views

will this timer/delay circuit works as intended with almost equal opamp inputs?

I just saw this video about a so called delay circuit using opamp in comparator configuration. The author mentions to use a pot as a voltage divider to feed the (+) input and the node between a series ...
1
vote
2answers
288 views

Driving solenoid valve using LM358 as comparator and ULN2003

I'm trying to drive a 12V DC solenoid Valve with following diagram. In 1st block the PC input is compared with 2.2V and its output goes to block2 and ULN2003 for driving the valve. The 2nd block is a ...
0
votes
0answers
115 views

Strange output from latch connected to comparator

I'm trying to make a latch (in ltspice), so if the comparator output (A) goes low, the latch will trigger and C will go high. C should stay high, irrespective of whether A goes high or low after that. ...
5
votes
2answers
595 views

Why such analog comparator input setup?

My understanding of an analog comparator is that you have a fixed reference voltage applied to one input and an AC signal to the other input, when the signal's voltage > reference voltage, the output ...
0
votes
2answers
43 views

Truncating negative results of Op amp by rail limiting

I have a signal that will swing from -5v to 5v. I am interested in the 0 to 5v part only. I will set a reference voltage and give it and the signal into a comparator. The comparator's rails are 0, and ...
-1
votes
1answer
217 views

Band-pass and LM358 based rhythmic light

I was asked by a friend to build a simple circuit to have a light flash depending on the bass of a song (mainly techno music). This is my idea: The circuit works on 9V to be powered either by ...
1
vote
2answers
280 views

Feedback capacitor in comparator circuit with an OP-AMP

Greetings, This is a scheme of a comparator with dynamic hysteresis. Green line is the output Red line is the input Blue line is the positive feedback. I want to ask for the explanation why C1 does ...