Questions tagged [comparator]

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

0
votes
1answer
60 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
48 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
2answers
108 views

Sawtooth signal

I'm trying to create a sawtooth signal using low cost pasive and active components. This will allow me to compare it to an analog signal to output a PWM signal. My sawtooth signal have to be at least ...
0
votes
0answers
72 views

Convert linear voltage to PWM

I'm trying to convert a linear voltage to a 21kHz PWM signal using passive and active components. Do you have any idea how I can achieve this ? I tought about comparing my linear voltage to a ...
0
votes
2answers
64 views

Comparator circuit with hysteresis window adjustment + offset?

I am looking for a circuit that allows the user to adjust the delta (= hysteresis window) between thresholds using 1 pot. and offset the thresholds using another. For example - Using one pot. the ...
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
3answers
188 views

Is there a frequency comparator device? [closed]

Is there a comparatorlike IC device which compares input frequency with a threshold frequency? I want to make a circuit which monitors input pulse train and whenever it is more than a set frequency ...
0
votes
1answer
50 views

output of comparator

I am using LM139 comparator There are two stages of the circuit: First stage is amplifier stage Second is comparator stage I apply input signal of 1.098Vac to noniniverting input of LM139 comparator....
0
votes
0answers
49 views

Switching on LED when voltage is (almost) zero

I'm a newbie with a project, and I'm trying to learn from it, but I'm in moment of total confusion. Background: I've got a campervan fridge that works on gas. There's a flame sensor which is ...
0
votes
2answers
83 views

What is the use of these resistors in the schematic?

I am trying to build a line-following robot with the schematics I found below. I understood that the comparator is used as the logic for the robot and there is no need for a feedback loop for the ...
3
votes
1answer
83 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
47 views

Questions about an on-off control comparator circuit driving an SSR

I was doing on-off temperature control for around 40‎°C for an enclosed unit manually by switching on and off a 1100W heater(with a fan) with my hand. The accuracy is not very important roughly 40‎°C ...
3
votes
2answers
74 views

What causes those oscillations in a comparator circuit

I designed a simple class D amplifier based on theory (output stage not pictured): Layout(ish, the board was modified in a few places, the whole top part is a separate PCB soldered into where some ...
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-...
2
votes
3answers
77 views

Frequency to voltage circuit with LM339 in KORG MS-20 synthesizer

This is an extract from KORG MS-20 synth schematic. The purpose of the circuit is to convert frequency into voltage (with Hz/volt implementation, double the pitch and double the voltage). The part I'...
0
votes
1answer
76 views

How to analyze this opamp circuit with logic gates, Zener diodes and transistors?

This is the circuit with this values: $$\text{Logic gate of CMOS,VTH=2.5v,VCC=5v,Vz=3.3v,Vd=0.7,VBE=0.7}$$: The left side is working like a SR FF , and the right side Schmitt trigger comparator and ...
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
1answer
123 views

Why does adding a capacitor greatly improve this circuit?

I've been prototyping this pretty simple circuit for a while now: simulate this circuit – Schematic created using CircuitLab Description: C3 is charged to set point. Compatator out put goes ...
0
votes
1answer
76 views

Comparator loses voltage when connected to mosfet

I want to make a discharger for 18650 batteries so I can store them at a specific voltage. I built a comparator (LM393) with a voltage reference to 3.8V at the inverting input and the voltage of the ...
1
vote
2answers
47 views

Dual Comparators connection that affect the design

If we use a dual in package comparator Example LM2903 and do use only one comparator, what should be done with the other one. It is sure that paralleling the two comparator will cause instability and ...
0
votes
0answers
45 views

Solar power pump - Design critique and help

Okay so, I have a design that 'works' on the breadboard. But I feel like it could use some improvement. Here is my current design: simulate this circuit – Schematic created using CircuitLab ...
0
votes
2answers
56 views

window comparator with TLV3402

I made a simple window comparator like this: I'm using LM293, R1 and R2 sets a Vlow and Vhigh threshold, when input is inside Vlow and Vhigh, both leds are off, when input is above or below, one of ...
0
votes
1answer
64 views

Relaxation Oscillator Issue, comparator self-oscillating at 25 MHz (40ns propagation delay)

I have a relaxation oscillator circuit, which is supposed to oscillate around 6 MHz, and mostly it oscillates in a very stable manner around it. However sometimes it starts to oscillate at 25 MHz, ...
0
votes
2answers
65 views

Hysterisis - How do you choose a good value for R3?

simulate this circuit – Schematic created using CircuitLab Above is the basic schematic for a comparator with hysteresis. Determining the values of R1 and R2 is fairly straight forward. They ...
1
vote
2answers
62 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
3answers
54 views

Coilgun - IR sensors interference

I´m working on my coilgun prototype, but I have troubles with IR sensors for projectile detection. When any of accelerating coils is switched off, all sensors report false detection. I´m using this ...
0
votes
1answer
54 views

diodes at the output of window comparator

Can anyone explain to me the function of those two diodes?
0
votes
1answer
18 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
0answers
71 views

wrong frequency of LC based generator with LM311

I have a problem with the frequency of LC meter based on comparator (a very popular solution, similar to this one: http://www.vk6fh.com/vk6fh/lc_meter_vk6fh.htm). I have recreated generator part in ...
0
votes
2answers
55 views

How does the comparator set the motor speed at a fixed level?

How does the comparator below sets the motor speed at a fixed level? I can think that the comparator output will turn ON if the speed proportional generator output voltage is lower than the zener ...
0
votes
1answer
47 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
1answer
61 views

How to detect low RTC battery with low extra battery load?

I want to detect low battery in typical DS1307 circuit with microcontroller. My first idea is to connect one of low cost comparator inputs to Vbat, another input to 2.0V from some voltage divider ...
0
votes
0answers
36 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
69 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 ...
1
vote
2answers
77 views

Design Considerations for comparator with ~1mV accuracy?

I am working on building an "exploded" analog to digital converter (ADC) (tracking type: up-down counting) for teaching purposes. I am working with a 0-5V reference, and 12-bits of precision (values ...
4
votes
3answers
117 views

UVLO for Energy Harvester circuit

A good background on the problem can be found in the document: (Under Voltage Lock-Out Design Rules for Proper Start-Up of Energy Autonomous Systems Powered by Supercapacitors). The above document ...
10
votes
2answers
546 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
71 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. ...
0
votes
0answers
38 views

Comparator resolving input voltages close to vdd

I have a design problem to solve. The problem statement goes as follows: "Design a clocked comparator resolving input voltages close to vdd dissipating less than 100 uA". What does "resolving input ...
-1
votes
1answer
91 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
103 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 ...
1
vote
3answers
213 views

LM339N - Comparator #4 not working as expected (always low)

I've designed a circuit for a battery indicator for my 18V Li-ion battery pack, based off this example here: https://www.electroschematics.com/8347/24v-battery-level-indicator/ I have it laid out on ...
0
votes
1answer
72 views

Analog Comparator Design

I've been brushing up on my analog design, and have some questions regarding improving the design of a simple comparator. It's been a while since I got this deep into it. I'm trying to implement it ...
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 ...
1
vote
5answers
154 views

Schmitt Trigger hysteresis

I am studying comparators and Schmitt triggers. And I did not find anywhere how to choose the value of hysteresis. I understand its purpose and I know how to calculate it. But what value is needed for ...
0
votes
1answer
46 views

Basic circuit to turn on LED when input detects signal (for guitar)

I'm looking for a basic circuit snipping which can either turn on an LED or give a positive voltage when input signal from a guitar is detected. Basically, I have an existing circuit where an effect (...
0
votes
1answer
53 views

How to interface a passive inductance sensor output (audio-level signal) with Arduino?

Would like to interface two passive magnetic-inductance sensors output (audio-level signal) with Arduino. The sensor circuit comprises of two wire-wound sensors and has no power. It generates it's ...
0
votes
4answers
61 views

Comparator with Alternate LEDs

I want a simple comparator circuit that lights one LED when voltage is above ~1V and lights the other when below. I'm sure I'm missing a basic concept, but it seems like this circuit should have that ...