Questions tagged [duty-cycle]

Duty Cycle is the ratio between duration of a pulse and the entire period of a (repeating) square wave, expressed in %.

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61 views

PNP transistor interface is not switching PWM inputs with low duty cycles

The following transistor circuit section(using a PNP transistor BC557B) is inverting and buffering a 25kHz PWM pulse train coming from one of the Nano's PWM supported digital pins. The following is ...
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53 views

Current rating vs duty cycle

Is there a rough relationship between the current rating of a device, say a connector, and the duty cycle? For example, I assume a connector rated at a continuous 5 amps isn't necessarily going to be ...
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39 views

How to measure current in very low duty cycle circuit with DMM?

My circuit has 4Hz 50% duty cycle. How do I measure the average current using a DMM? I have a Fluke 87 DMM. It has an average setting but for 100 ms which less than one complete duty cycle. My ...
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41 views

Buck Converter MOSFET Output Voltage distorted (PWM)

The input to my buck converter MOSFET switch is a PWM signal with a certain duty cycle. However, upon observing the voltage waveform of the MOSFET, the voltage is a bit distorted. The input to ...
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1answer
40 views

SIMPLE digital control over 555 timer frequency and PWM?

I'm looking to create a sound generator with only simple ICs and components. I believe the 555 timer IC is a good candidate to be at the core of it, but I cannot for the life of me find out how best ...
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2answers
65 views

Thermal calculation in case of duty cycle for a mosfet

For a multiplex LED matrix, I am intending to use two ULN2803's as sink source for 16 times 20 mA per column (channel). However, maybe I will try a test with 100 mA LEDs (10% duty cycle). For that I ...
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1answer
741 views

STM32 PWM problem

Using a STM32F407 board. I want to generate a PWM signal. I have the following function: ...
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1answer
116 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 ...
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1answer
53 views

Which Approach is Better to Drive Brushless DC Motor with PWM Duty Cycle

I'm doing a project that use brushless geared DC motor, the motor is connected to a moving platform. I will drive the motor with PWM, the motor then move the platform from -a degree to a degree ...
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1answer
55 views

High and Low times for 555 oscilator are inverted

I’m new to electrical engineering and this is my first time working with an oscillator. I'm trying to setup a 555 timer ic as an oscillator with a low time of 1s and a high time of 0.5s. I've been ...
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2answers
38 views

Run actuator at higher voltage and with lower dutycycles

I have an actuator which is rated at 12 VDC input voltage (0-15) with a maximum allowed duty cycle of 20%. The already existing voltage levels in my system are 5V and 22V, and since I am weight ...
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1answer
262 views

How to measure duty-cycle with Input Capture from STM32F103C8T6?

I'm trying to measure the duty-cycle of the 0-5V electrical PWM signal I have generated from the any source. How can I do this? Anyone can help me? IDE: Keil Microcontroller: STM32F103C8T6
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109 views

What is the physics behind width of the duty cycle in Arduino?

I was wondering if someone can tell me how Arduino changes the width of the duty cycle? How it produces an on-off pattern? I am looking for an explanation for modulation in this system.
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1answer
36 views

Determine MC34063AP Duty Cycle

A fuzzy area I want to clear up on the MC34063AP is Duty Cycle. In the MC34063AP datasheet, toff an ton are a result of 1 / f, which is obvious. toff is calculated by: 1 / f / ton / toff + 1 ton ...
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2answers
74 views

DC motor parameter identification using microcontroller

I've built a DC motor controller which measures the speed and current (not really sure yet about current values) of a permanent magnet DC motor. I plan to connect different PM DC motors. Is there a ...
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0answers
105 views

Optimal duty cycle in Forward converter?

So as far as I understand the Forward topology: The duty cycle set by the controller in CCM mode is constant assuming constant input voltage and constant output voltage. The duty cycle is independent ...
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4answers
2k views

Servo PWM: Why 20 ms period?

I'm working with ESC controllers which receive PWM signals that are very similar to those that control a standard Servo motor, i.e. a 50 Hz PWM signal (20 ms period) with duty cycle of 5-10% (1-2 ms ...
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1answer
173 views

Basic definition of duty cycle

Does the definition of duty cycle indicate only the percentage of time that the level is asserted? For example, if a 10 Hz square wave is de-asserted for 5 of those 10Hz cycles and asserted for 5 of ...
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3answers
433 views

how to make a square wave 1kHz circuit [duplicate]

i want to make a 5V oscillator that has a frequency of 1khz. it will basically go to 5V (HIGH) and then 0 V (low) in a frequency of 1khz with 50% duty cycle.
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2answers
102 views

Is it possible to generate different PWM Signals for same duty cycles(e.g. 50%)?

Let us expect we have a duty cycle of 50%. Is it possible to reach that duty cycle with different PWM Signals (waveform)? With different I mean variants in the number and lengths of the "active time". ...
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2answers
320 views

How to regulate PWM to control a boost converter

I am creating a simple boost converter following the classic circuit diagram just for learning purpose. The switch is a power transistor controlled by PWM output of an Arduino (with additional ...
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1answer
286 views

Defining contrast ratio and dimming ratio in a LED driver

I read in this article which analyze the contrast ratio achievable with switched mode LED driver system, that is defined as \$ \frac{1}{t_{on}} : 1 \$. Intuitively I can get that the minimum time ...
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0answers
42 views

Analysis of the full bridge bidirectional converter's buck mode operation?

This is the circuit I was trying to learn. Here is the equivalent of the buck mode operation: And following is the waveform in the buck mode of operation: My intention is to derive the output ...
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1answer
125 views

How can I add variable duty cycle PWM to a CircuitLab simulation within a question?

This is my first attempt to simulate a circuit in the time domain with CircuitLab. In order to ask a proper question about something similar driven with PWM, I'd like to add an adjustable duty cycle ...
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1answer
121 views

Control the duty cycle of my square oscillator

I Would like to know how i can control the duty cycle of my circuit. simulate this circuit – Schematic created using CircuitLab What is the best way to control the duty cycle ( from 1 to 99%) ...
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4answers
2k views

analog PWM signal

I am trying to get a PWM signal with adjustable duty cycle using only analog components, hence using a timer is not possible. Now I got one way of using it, using the triangle waveform and putting it ...
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1answer
814 views

Pulse generator with single op amp and diode

I want to design pulse generator with specific period and duty cycle. I found a pulse generator with single op amp and diode. I couldn't find information about how to calculate period and duty cycle. ...
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1answer
2k views

Driving servo motor with PWM signal

I want to drive servo motor with PWM signal.Servo motor rotation angle changes with the ratio of the duty cycle.Generally , servo motor rotation angle according to PWM can be seen in figure below. ...
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2answers
329 views

The logic schematic which can change the duty cycle of input

Is there a logic schematic can change the duty cycle of input ? I mean if input is a square wave with duty cycle is equal to 50%,and the output is also a square wave but its duty cycle become lower or ...
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2answers
2k views

independent control of frequency and duty cycle in 555 timer (formulas)

I want to control frequency and duty cycle of output pulse of 555 timer. I searched and find this schematic in a post in SOV but I don't know how calculate frequency and duty cycle in the circuit. ...
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2answers
1k views

how do I control duty cycle of a MOSFET using PI controller

I have designed a buck boost converter, how can I use a PI controller which will automatically change the duty cycle of the mosfet as per my desired output voltage or current? I have been fidgeting ...
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1answer
119 views

'Subcircuit is undefined' when designing PWM with TL493 in PSPICE

I am trying to design a PWM for my converter using TL493 in Pspice and i am getting an error. ERROR(ORPSIM-15108): Subcircuit model591_tl493 used by X_U1 is undefined i am a beginner to both ...
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2answers
2k views

Do 100% duty cycle buck converters have no voltage drop?

I am currently designing a circuit which should be able to take 12-28V DC power in and output 12V DC @ 1.5A. The question is: is this possible with a 100% duty cycle buck converter (like TPS54302)? ...
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1answer
66 views

Duty Cycle Demodulation Distortion Correction

I'm trying to come up with a system which will reliably convert an arbitrary input to a PWM signal, and then back again. The comparison signal is a 50kHz sine wave, and the result is fed through a ...
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5answers
4k views

Is there a way to sweep duty cycle over time in LTspice

I can sweep the frequency in time by using modulate, but I couldn't find any example on creating a varying duty cycle or a duty cycle is swept from zero to 100% at a given frequency f in a time ...
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1answer
217 views

Average voltage (pwm regulated) out of motor voltage range?

My DC brushed motor is rated 4.5V-15V. My application requires the motor to spin with different speeds so I am using PWM to regulated the it. I will be supplying the motor with a 12V battery and using ...
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4answers
1k views

100% Duty Cycle PWM

I recently had to build a filter to go from PWM to 0-5Vcc, and it got me thinking... At 100% duty cycle, the PWM used was 100% 5V output, DC voltage... If i used this PWM to, for example, switch a ...
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4k views

DC motor speed vs PWM duty cycle

I understand there have been quite a few posts asking about the DC motor speed vs PWM duty cycle issues. However, I found those questions different from what I want to ask, so I have to ask this topic ...
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1answer
2k views

555 - Adjusting frequency without affecting duty cycle

This seems to be some easy thing someone figured out already, but here I am after an hour of searching - and fearfully asking the question. My aim is to build a relatively simple 555 circuit using as ...
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1answer
74 views

How to keep a 110V appliance ON for 1 minute every 5 minutes, without arduino? [closed]

I need to turn ON an appliance (110V, 0.5A) for 1 minute every 5 minutes. The immediate solution that comes to mind is arduino/raspberry-pi and with a relay. What kind of circuits would help me ...
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1answer
54 views

Thyristor in a choppercircuit

I've the following kown values: Switching on loss is \$\text{E}_\text{on}\space\text{J}\$ in \$t_\text{on}=\tau_\text{on}\space\text{s}\$ Switching off loss is \$\text{E}_\text{off}\space\text{J}\$ ...
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1answer
1k views

IC Timer 555 Astable Multivibrator 50% Duty cycle

I'm given this configuration to solve for a IC-Timer 555 in astable mode to get a 50% duty cycle however I'm having some difficulties in the calculations. The circuit is modified a bit as shown. ...
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0answers
419 views

What difference a change in hertz vs duty cycle make to the pitch of a sound?

For example, 100 hertz sounds very low, but acquiring that from an online source that doesn't tell me the duty cycle doesn't answer my inquiry into whether a change in the duty cycle will affect the ...
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1answer
501 views

Pulse width modulation sensor circuit

This is the circuit of a PWM temperature sensor, I will give you some details about the circuit: The Electronic control Module which supply power (+8V) at terminal (A) The Electronic control Module ...
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1answer
76 views

mechanical oscilator concept to drive electric motor [closed]

I have been thinking about a project for some time now and am wondering how well it may work. I would like to make a sleve which could be run by a small electric motor ie from an old cd player or rc ...
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2answers
764 views

What is the influence of an asymetric load capacitance on a crystal duty cycle

I have a crystal oscillating at 25MHz (datasheet). The recommanded load capacitance is 18pF according to the datasheet. The crystal is connected to a component where the capacitance on the pin are ...
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2answers
176 views

Is a switching power supply likely to fatigue or burn out early if turned on or off quickly?

I'm working on a design for growing biomass where I need high power LEDs to switch on and off somewhere in the neighborhood of 1-30 times per second, so that they provide light to grow but don't ...
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1answer
153 views

Can't understand a variable in the formula used to determine CDTY to set duty cycle of PWM on cortex M3 (SAM3X8E)

I want to generate complementary PWM on an Arduino due. For that purpose I am programming the cortex M3 using the PWMC library. In order to set the duty cycle I have to set a value in CDTY channel ...
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2answers
152 views

High Current Pulse Opamp 2.5% Duty Cycle

I am driving an IR LED (LED914 and LED907) in series at 4.5 A for 2.5% duty cycle, In the 28 V I connect a DC supply and set the current to 150 mA, the idea is to continuously charge the capacitor C17....
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1answer
1k views

PSpice PWM duty clycle generation from PID controller

I am trying to implement an ideal PWM controller in for an analog circuit I have in ORcad PSpice. Ideally I would use the SLPS tool for simulink, but unfortunatelly we do not have the licence for it ...