Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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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Joule Thief - operation and the 'supercharged' version

I've made a Joule Thief, and it works fairly well, but not as well as I would like. It's powering a 3.2v LED from a 1.2v battery, but it's very dim. I'm hoping that increasing the voltage from the JT will improve it, but I'm not sure how to…
Alex Freeman
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Measuring cpu load of interrupt routine

I have an isr that is updating a display at a fixed frequency. I would like to tune my routine to minimize overhead and keep as much cpu time as possible open for other processing, but I don't have any good way to collect metrics to determine my cpu…
captncraig
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Boost Converter Efficiency goes down as Duty Cycle goes up?

simulate this circuit – Schematic created using CircuitLab I have tested a boost converter under different duty cycles. I know the voltage is related to the input voltage by V = Vin/(1-D) where D is the duty cycle. But for some reason, as I…
AAC
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Frequency of an applied PWM to a motor

What kind of behaviour change should I expect to see, if I feed a 12V 50kHz frequency, with 50% duty cycle, or a 100Hz 50% duty cycle, across a DC Motor?
Sherby
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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. So I found a post in the AllAboutCircuits forum…
PStechPaul
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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 pulse time of ~50ns, which means I need rise and fall…
flimsy
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Diode IFSM to duty cycle extrapolation?

I have a diode. It has a forward current rating of 40 mA. It has a surge current rating of 100 mA for t <= 10 usec. There is no mention of a duty cycle in the datasheet. Is there a rule of thumb for determining what kind of off period I need in…
ajs410
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How do I calculate battery life allowing for duty cycle?

I have a battery rated at 2610mAh. The device it's powering transmits to the network for 35ms during this time it uses 1.95mA of power. the rest of the time the device draws 0mA. I want to workout how long the battery would last in seconds. Here's…
mintyfreshpenguin
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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?
kellogs
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STM32 PWM problem

Using a STM32F407 board. I want to generate a PWM signal. I have the following function: /** * \brief Sets the CCR timer register. The register determines the duty cyle. * \param ChannelNumber: channel index from channels configuration…
pantarhei
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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 throw a comparator with the voltage supply, the…
user183026
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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. simulate this circuit – Schematic created using…
Mr. Nobody
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555-timer circuit supposed to give 50% duty cycle square wave doesn't

I wanted to build a circuit that gives 50%-duty-cycle square wave. I built the circuit of figure 4.4.6 from this link which is shown below: I used the NE555 chip, and used a potentiometer instead of the resistor. The resulting waveform is shown…
ammar
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Using 555 to generate square signal with fixed duty cycle / variable frequency

I am attempting to design a circuit whose output is a square wave with the following properties: Fixed duty cycle, as high as possible (let's say 99%) Variable frequency, between 0.2 - 20 Hz (I'm somewhat flexible about this range) I imagined…
jptacek
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Opamp relaxation oscillator (single supply)

I simulated and built current circuit. What I got was a rectangular wave generator with a duty cycle significantly lower than 50%. Than I made R3 = R4 and got 50% duty cycle. I managed to think that RC constant is defined only by C1 and R1. It…
ivan
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