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 %.
187
questions
0
votes
0
answers
30
views
FTDI SPI has short pauses between bytes. Is this expected? [closed]
I am using an FT4232H module for an SPI communication.
Even if I am using the MPSSE engine, and ft_write command sending many bytes together, what I see is a clock ...
- 1
0
votes
2
answers
96
views
Voltage not varying with duty cycle
I want to make a circuit that changes voltages with the duty cycle as well as doubles that for me. I therefore made a voltage doubler circuit along with alternating PWM wave. But as I changed the duty ...
- 463
0
votes
1
answer
26
views
Understanding violation of the common mode voltage range of the input in ZCD [closed]
Trying to reproduce an analog circuit using LM324 to have at output 100Hz squarewave 5% duty cycle from 230Vac mains frequency.
The circuit has to be in sync with it. Picture and LTSpice simulation ...
- 3
3
votes
4
answers
180
views
Schmitt trigger transistor duty cycle
I built this Schmitt trigger using transistors (2N3704).
Input is a square wave coming from an OCXO, 1 MHz, 50% duty cycle.
I obtain a square wave with 70% duty cycle. What can possibly be the cause?
- 101
0
votes
1
answer
66
views
PWM IC duty cycle not increasing
I was working on the UCC3895 PWM generator but am having a problem getting a complete duty cycle up to 100. I have used the following diagram for my circuit:
I wanted to use the UCC3895 to get a PWM ...
- 463
0
votes
0
answers
25
views
PWM phase shift controller IC confusion
I was reading one of the datasheets regarding the control of an H-bridge i.e. UCC3895. As far as I understand, this is a PWM controller to drive a full bridge inverter. I have a few confusions ...
- 463
0
votes
4
answers
93
views
NE555, 50% duty cycle at 110kHz
I want to get an NE555 chip with a 50% duty cycle to 108-110kHz in output.
I have already experimented with various online calculators and values. However, I never get the values that allow me to do ...
- 89
0
votes
0
answers
35
views
Output time period of each pulse signals to determine the duty cycle
Dear all,
I build on an oscillator and want to detect its duty cycle in order to compenstate the oscillator which is used to sensing the environment change.
After I get the V(vtime_all) which shows ...
- 1
0
votes
3
answers
132
views
What is the formula for measuring squarewave duty cycle from a spectrum?
Several engineers have told me that digital signal (squarewave) duty cycle can be measured accurately by comparing the amplitude of the 2nd (or 3rd - says another guy) relative to the fundamental. ...
- 11
1
vote
1
answer
51
views
Duty Cycle and Filtering in Switching Power Supplies
I have a few confusions to clear up. The first one is about the switching power supply.
Does the power supply simply work on the bases of the duty cycle? Like If I have a pulsating signal of 50% duty ...
- 463
0
votes
0
answers
74
views
STM32 PWM output duty cycle is not accurate
I am using an STM32f051C8T6 and I am trying to control the PWM duty cycle, however, the duty cycle is inaccurate. I set it to be 50%, but the output is less than 40%. Also, the frequency is wrong; I ...
- 1
0
votes
0
answers
78
views
Duty cycle that varies with time
Controlling the intensity of an LED with a 555 and a potentiometer is fairly straightforward. Like this circuit (feel free to criticize).
I would like to go one step further and have the duty cycle ...
- 101
0
votes
2
answers
105
views
Maximum voltage of a PWM
It seems that some buck converter designs use PWM to change the average voltage sent to the load : which means that for it's (ON) duty cycle, the load will see a higher voltage than required/specified ...
2
votes
0
answers
145
views
Flyback transformer design process review
I was hoping I could get some verification on my flyback design process, and some questions answered.
The document I was following is from Fairchild, AN4137, and the steps below essentially outline ...
- 118
0
votes
1
answer
91
views
Square wave (+-15V) to positive DC
How can I convert a square wave signal from -15V to 15V to a positive DC signal?
Here are the details of my problem:
I'm trying to build a duty cycle for a buck converter in the following way: I want ...
- 337
0
votes
1
answer
87
views
Relationship between pulse forward current vs pulse duration
I'm having trouble understanding why this application note for this proximity sensor suggests reducing the current for the IRED depending on the on time pulse duration. What is the relationship ...
- 51
0
votes
0
answers
193
views
Servo motor duty cycle to angle
I am trying to control a servo motor using a square signal with a varying duty cycle. The data sheet of the motor says that the frequency of the signal should be 20 ms.
In addition, if I need to ...
- 1
0
votes
0
answers
60
views
Tiva C Measure PWM frequency and duty cycle
I´m trying to measure the frequency and duty cycle from a PWM signal, my code works OK but when the PWM signal is not active (0Hz 0%) the values of Freq_C4 and DutyCycle_PC4 still reminder the values ...
0
votes
2
answers
215
views
PWM converters: operation over and under 50% duty cycle
I have a DC/DC Flyback converter based on the UC2844 regulator and I would like to use other regulators of the same UCx84x family.
Reading the datasheet, I found that there are regulators that can ...
5
votes
2
answers
291
views
In LTspice, why does sine wave PWM simulation fail for small and large duty cycles?
I had been trying to find a way to simulate a PWM signal for a sine wave, other than using a large and cumbersome PWL file, or using a comparator between a sine signal and a sawtooth for the carrier. ...
- 7,325
0
votes
1
answer
69
views
Formula for current vs duty cycle in step-up pwm circuit?
What is the formula for average current with step-up PWM circuit (and about 30 kHz frequency and 300 uH inductor) that charges battery at 72 volts, and source is 24 volts, relative to duty cycle? I ...
- 1
0
votes
1
answer
46
views
Stretch duty cycle of square wave where amplitude changes
I have a signal coming from a photodiode detector, the pulse is really short, so the integration time is very small, and the total power measured is very small (very close to the noise of the detector)...
0
votes
2
answers
84
views
Circuit for producing logic high when input is oscillating
I want to make a circuit which produces a logic high signal upon receiving an oscillating input voltage. In the past I have gotten away using an RC delay signal. When my input signal wasn't ...
- 1,223
1
vote
1
answer
84
views
Calculate duty cycle of device's on and sleep state to drain coin cell in given amount of time
I am trying to drain a 25 mAh ECR1216 coin cell in 2 days. My device draws 6 mA when on, and about 15 μA when on standby.
I am having a hard time determining a duty cycle for on/standby time to drain ...
- 15
4
votes
5
answers
611
views
Impedance, square waves, and duty cycle
Will a coil present a different impedance to a 10 kHz sine wave as opposed to a 10 kHz square wave with a 10% duty cycle?
I could not find a way to calculate it, are there any formulas available?
- 1,050
0
votes
1
answer
85
views
Question - LC Tank - Resonance , Duty Cycle , Back EMF
I was wondering about that for some time now but didn't have the time to try it myself , maybe some of you guys will help me out with this question :
What happens when LC Tank is operated in its ...
- 71
0
votes
2
answers
310
views
TLC555 Constant Frequency, Adjustable Duty Cycle [closed]
For my Senior Design Project, I am designing a battery charger based on a synchronous buck converter topology.
The MCU (Teensy LC) I'm using cannot produce PWM with a high enough frequency (488.28Hz), ...
1
vote
2
answers
196
views
Change the duty cycle of pulses
I'm trying to raise the duty cycle of short pulses (about 10%) through the range up to ideally 80% using a potentiometer. I've seen variable pulse generator designs using 555s, but my trigger is ...
- 123
0
votes
1
answer
156
views
How to optimally decide modified square wave duty cycle for an inverter?
Some high-end inverters synthesize a sine wave with high speed pulse width modulation and low-pass filtering, but most cheaper inverters use a square wave or a modified square wave.
Modified square ...
- 1,563
1
vote
2
answers
256
views
Could a CPU execute the fetch-execute cycle without a microsequencer/microcode?
VERY SPECIFIC QUESTION, PLEASE READ THROUGH ALL OF IT
From wikipedia:
"The sequence of operations that the control unit goes through to process an instruction is in itself like a short computer ...
1
vote
1
answer
200
views
PWM signal generator circuit does not work in real life
I designed the motor soft start circuit in the figure below.
I ran the circuit in simulation programs, but when I tried it on a breadboard in real life, I could not get a PWM signal.
When I examined ...
0
votes
1
answer
259
views
While using this library (FastPwmPin.h) output frequency is coming exactly but not duty ratio?
I am doing a simple power supply for that I need PWM signal to turn ON and OFF the MOSFET. For this I am using arduino UNO for PWM signal generation. So I used a library called FastPwmPin.h to ...
- 15
0
votes
3
answers
141
views
Adressing timing issues on a pipelined logic circuit
Original title: How to modify the duty cycle of crystal oscillator?
I have a 25.175 MHz crystal oscillator with a duty cycle of 50%. How can I reduce the waveform to a 25% duty cycle?
It doesn't have ...
- 123
0
votes
1
answer
207
views
Making duty cycle with CTC mode in AVR without using interrupt
I am writing a program to make an output with a 30% duty cycle and a frequency of 3 kHz using an ATmega32 microcontroller. My controller's frequency is 8 MHz and I am going to decrease it to 1 MHz by ...
- 73
5
votes
3
answers
1k
views
Increase minimum PWM duty cycle for high resolution PWM
I'm working on a project involving driving LEDs at a 20kHz PWM frequency with 1024 bit resolution. I've calculated that the minimum pulse time, (1/frequency)/resolution, would result in a minimum ...
- 363
1
vote
2
answers
462
views
I have modified a simple blocking oscillator. How can the frequency, duty cycle or efficiency be otherwise increased?
In this schematic is a simple blocking oscillator. Note that this won't simulate, as Circuit Lab does not have the type of toroid needed, but if you breadboard or prototype this circuit it will work ...
- 165
-3
votes
1
answer
310
views
precise 50 Hz oscillator [closed]
I need an astable multi-vibrator at exactly 50 or 100 Hz with exactly 50% duty cycle.
using circuits like 555 can't give me that with the common well-known values of components R and C , let alone the ...
3
votes
3
answers
1k
views
Precise square wave generator 32768 Hz
I need to create a circuit to generate a square wave with 50% duty at 32768 Hz +/- 5 Hz. The output of the circuit will drive an NPN transistor ( 0.2 A , 24VDC ).
The cost of the component is not a ...
0
votes
1
answer
119
views
How can an instruction be fetched every cycle?
From what I understand, in a pipelined CPU, every stage takes 1 cycle. But instructions are fetched from memory which takes up to ~150 cycles. The CPU fetches most instructions from the L1-cache, but ...
- 3
0
votes
1
answer
97
views
Varying duty cycle of an square signal using comparator
Recently i've been tinkering with the interrupter of my solid state tesla coil and the circuit that utilizes two ne555 timer ic,one in astable mode and another one modulating via pin 5 of the first ...
- 59
0
votes
2
answers
108
views
Can I reduce flyback transformer into a single inductance to calculate the duty cycle of the MOSFET?
I am trying to calculate the duty cycle of the MOSFET in a flyback topology SMPS. From the selected converter's datasheet, I am given the equation:
Since I am using a flyback topology, what is my L ...
0
votes
1
answer
248
views
Laser Power Control Using Duty Cycle
I have a Coherent Cx-10 CO2 laser that I want to use for laser heating of very small samples at high pressure, so I need to accurately control the laser power. I also have a pulse width modulated ...
0
votes
3
answers
125
views
Can't figure out this PMDC motor model
I was going through a series of experiments on PMDC motor where I found out the following block diagram representing the system:
I'm new to this field and I'm trying to get a little ahead of my ...
- 117
0
votes
0
answers
534
views
Output voltage from L298N
Is it normal to have a higher output voltage than expected from an L298N driver?
I have read that there are voltage drops and it is usual to have lower output voltages, not higher ones. If it is a PWM ...
- 37
0
votes
0
answers
91
views
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 ...
- 11
-1
votes
2
answers
382
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 ...
0
votes
1
answer
132
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 ...
- 1
0
votes
1
answer
68
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 ...
- 366
0
votes
1
answer
44
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 ...
- 159
2
votes
2
answers
786
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 ...
- 1,722