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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What Happens when PWM Period register and Compare register is also loaded with same value

Consider, PWM engine based on timers, PWM period register is loaded with 0x3FF (10bit, specifies the period of pwm frequency) and compare register( to vary the duty cycle , when timer count = cmp ...
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126 views

555 Timer duty cycle changing formula

I am making a PWM motor speed controller. I used the Astable mode thinking it would work; it did not. Using an oscilloscope I noticed that I am only changing the frequency not the duty cycle by ...
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57 views

Factoring duty cycle into battery design, give battery life

I have been given the following scenario: LED output: • assume 200 communication codes per 24hrs, and that each of those LED code words take 20msec of processor time to communicate BLE: • connect ...
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57 views

Error in compensator for buck

I'm trying to put my ZVS buck converter (DCM) in closed loop. I ran some simulations on MATLAB, and figured that just multiplying the transfer function of the open loop buck by 0.5 gives acceptable ...
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40 views

How to find the best settings for Cyclic voltametery test?

I am trying to conduct a CV TEST (Cyclic Voltammetry). However, I am unable to get the current peaks on my plot. I tried different ranges of Voltage at different scan rates. However, I could not ...
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93 views

How do you choose a PWM Frequency to drive a DC motor? [duplicate]

I can clock the PWM to drive motors at most any reasonable frequency, but is there a "best" PWM frequency for motor control? What must be considered when choosing a PWM Hz? Is there a most ...
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60 views

How to calculate duty cycle of a servo motor?

I have this servo motor and in its specifications only speed and torque is given: ...
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1answer
107 views

TL494 duty cycle adjustment

I'm building a simple pulse generator with a TL494 in single ended configuration. My plan is to set the frequency between 20Hz to 1kHz and duty cycle between 0% to 45%. I will adjust that with a ...
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3answers
46 views

Stepper Driver pulses control (with Arduino)

I intend to control the speed of a stepper motor thanks to a driver connected to Arduino (Mega). Basically the driver has, among others, 2 pins, PUL+ (Vcc) and PUL- (GND, common cathode), and each ...
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56 views

Boost converter depending on load

TL;DR: Output voltage of boost converter depends on load. I assume because the load is altering the voltage between the base of the boost transistor and ground, thus altering the duty cycle. No idea ...
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2answers
49 views

PWM signal duty cycle

I am using an Arduino UNO R3 to generate a PWM signal, the user sets the duty cycle using the serial monitor. The Arduino output signal is correct, but when the signal is connected to the input of the ...
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68 views

Is there a mathematical representation that represents the output voltage of a buck or boost converter in discontinuous mode?

Recently I have learned that in buck or boost converters, the output voltage depends only on the duty cycle and input voltage in continuous conduction mode or when current is continuous. However, in ...
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Why is the duty cycle much wider than it should be? PIC32MZ & PWM

I'm working with the PIC32MZ2048EFM100 and XC32. I'm using some outputs as PWM signal generators. There are frequencies for which the pwm works fine, but not for others. For example to get 24.4 kHz, I ...
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1k views

Duty cycle calculation

I am trying to solve a numerical where the Speed of a DC motor operating at 15V was measured to be 2000 rad/sec. Now a PWM signal is applied to the same motor to get a speed of 400 rad/sec. If the ...
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108 views

PWM output vs Digital output

Could I use a PWM output as a digital output? For example to act like an on-off signal by varying the duty cycle between 0 and 100%. Does it involve any difference in power consumption?
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94 views

I'd like to know whether my attempt to increase duty cycle will work

I've been looking for a solution to make an astable multivibrator give me a 90% duty cycle or a duty cycle above 50%. This is what I came up with. I have very limited resources and means of testing, ...
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132 views

How to make a pulse source with a changing duty cycle in LT spice?

I have a power electronic inverter, and I want to make the duty cycle of the PWM dependent on the ratio of "vout/vin", where vout is an AC power source. Unfortunately, setting .param D= IF(V(...
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95 views

Duty cycle of 555 timer

I am trying to understand the exact working of this circuit, I have been told that this circuit provides a duty cycle of 50% from my previous questions, the same which I successfully verified in ...
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76 views

Lower duty cycle less efficient?

Assume you have a DC voltage V, ideal switch (no switching losses) operating at some frequency f and duty cycle ...
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60 views

Is it possible to measure pwm load current using opamp based high side current sensing?

I am referring this app note, hope to use as unidirectional current sensing for a PWM load PWM load - load is a resistor, PWM signal - 100Hz, 150V. Load current 18mA Duty 5% (PWM resolution 8 bit) ...
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32 views

How can I cycle through 4 LEDs with Timer Off Function (TOF)?

I have 4 LEDs that need to be turned on and off sequentially and cyclically. This is my code from code warrior: ...
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1answer
53 views

Buck converters duty cycle

From this article: Power Tips: Power converter topology... they say that: Moreover, buck-converter duty cycles become extremely small in high-voltage AC/DC conversion. For a 440VAC to 15VDC ...
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34 views

Dutycycle DCDC control

I will start with that, i already ask for this question in other topic but i didn't have any anwser about my question link. Please don't go too far in explaning difficult thing not realated with my ...
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How to generate PWM with different frequencies and duty cycles?

I am going to use TMS320F28027 for PWM generation. I have to generate 5 different frequencies of PWM with different duty cycles at a same time. How it could be implemented? Can I use a single PWM ...
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226 views

Controlling Proportional valve with NPN transistor (TIP 122) using PWM

We are working to control the proportional solenoid valve (9C, 2W) (VSO by parker, datasheet) by changing the voltage across it. For this we are using PWM from the controller, thus changing the ...
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1answer
506 views

555 timer as a voltage controlled oscillator, duty cycle query

I`m trying to create a square wave generator using a 555 timer but i noticed that due to the pulse width modulation as i vary the control voltage, the duty cycle changes so i was wondering if there is ...
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133 views

Maximum AND minimum duty cycle in SPICE converter simulation

I am modeling a Push-Pull Converter in LTSpice and implemented this for a simple voltage feedback PWM control. This works great and I have added a bit on the end that allows for a maximum duty cycle ...
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476 views

Calculate duty cycle of flyback converter

MY ATTEMPT I found a formula for the DC transfer function for the flyback converter: $$\frac{V_{out}}{V_{in}}=\frac{N_s}{N_p}\cdot \frac{D}{1-D} $$where \$ \frac{N_s}{N_p} \$ must be the ratio between ...
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453 views

Using 555 timer with soil moisture sensor

I am using an IRROMETER sensor for soil moisture measurement. This sensor requires AC excitation, so I found an interfacing module for it from online. This is the circuit recommended by them: The ...
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19 views

How to handle duty cycle below deadtime in 2- and 3-level inverters

When programming a pwm for a 2-lvl inverter what would be the suggested strategy for a duty cycle close to 0% or 100%, meaning when I cannot guarantee for dead time. What would cause less distortion ...
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151 views

I need to vary the duty cycle between 50% and 70% of a PWM signal

So I used a comparator to compare a sawtooth signal and a reference voltage and I obtained the PWM signal at the output of the comparator. My question is what formula can I use to vary the duty cycle ...
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2answers
768 views

What is a best way to get a 25% duty cycle square wave (5 V, 1 MHz) on a board?

I am trying to get two off-phase 25% duty cycle square waves(1MHz) to control a full bridge circuit. Update:Sorry for the confusion here, what I mean was to have 2 square wave signals, and introduce ...
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57 views

Output Voltage of a Current Mode Controlled Flyback Converter

I'm trying to use the NCP1014 (65kHz) to make a flyback converter. I'm using coilcraft's transformer B0570-BL which is specifically designed for the NCP1014, with turns ratio 1:0.06 or 16.67:1. I ...
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207 views

20kg digital servo not working, probably because my frequency calculations are very wrong (raspberry pi)

summary I changed my servos for a more powerful one and cannot get it to work, I believe it is because I can't get the right duty cycle calculation in the code explanation I have a robotic arm that I ...
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97 views

Making PWM with analog input control in PIC18F4550

I am trying to program with the PIC18F4550 a PWM with which I can regulate the duty-cycle with a variable resistance. I attach my code to explain the problem I have. ...
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29 views

Drive signal (duty cycle) calculation for PI compensator

I am trying to simulate an inverter with 4 ideal switching devices in LTSpice. I have the compensator working, however I don't the correct equation in terms of calculating the duty cycle. What I ...
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2answers
992 views

When to factor duty cycle into power consumption calculations?

This is probably a simple question for most of you. I am calculating the power consumption of a device. The load is driven using a square PWM signal. At what point do I factor in the duty cycle? For ...
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216 views

How to generate a double PWM with a microcontroller?

I need to light a LED during a sequence with a microcontroller. The sequence is as follows : I need to turn on/off the LED with a given frequency (PWM 1). It will be between 1 and 200 Hz. When the ...
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1answer
491 views

SG3525 PWM duty cycle problem

I'm struggling to increase duty cycle in the controller. I'm using SG3525 on control PCB. As can be seen below, R12,R22 and C12 components are selected for 58kHz frequency. However, I can't get duty ...
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125 views

Limiting the pulse width of a PWM by using voltage divider and a single power supply

I'm using a Tl494 PWM and I want to limit the pulse width from 0% to 80% of the signal as maximum. How can I achieve this using a SINGLE 5v reference supply (I know it can be achieved by using two ...
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3answers
125 views

Range of duty cycle ms to drive RC servo motor and transfer function

I am using the ball and beam control system from Acrome robotics and I would like to identify the transfer function of the RC servo motor which translates motion to the system. First of all, I have ...
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1answer
75 views

How can I make smaller steps with my servo?

I've got a Raspberry Pi with which I control a servo. The servo controlls the rudder in an autonomous boat I'm building. I'm using Golang and this gpio library to control the PWM. The input I get ...
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1answer
150 views

Problems with DRV103 PWM

I've been doing some work lately with the DRV103 IC by Texas Instruments (datasheet here, essentially it creates a PWM signal of variable duty cycle and frequency, preceded by an 'ON' signal of ...
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3answers
520 views

Relaxation oscillator, how to change the duty cycle

I have a Relaxation Oscillator here. What I'm trying to do is to change the duty cycle of ca 50% to 10%. What I thought of and tried to change R1 and C1 values so the time the capacitor loads and ...
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1answer
61 views

Spectral lines vs Envelope of PWM wave

On the wiki page of 'Duty Cycle' there is a nice animation that shows the frequency spectrum of PWM wave as its duty cycle is modulated from 0 to 100%. The animation shows the 'spectral lines' as ...
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154 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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330 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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3answers
61 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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60 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
156 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 ...