Talk:Duty cycle

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Eh up I'm not an electronic engineer, so I'm no expert on this. Im a metallurgist using a laser for materials processing. We use duty cycle to describe the laser pulsing characteristics. Its usually expressed as a percentage like this

duty cycle = t/T*100%;

at least in the case of lasers

The time it takes for the welder to cool itself down so that it doesnt overheat.

Duty cycle in some equipment such as laser printers is a specification that no one seems to be able to define or explain. Peter Resch

Duty cycle in laser printers is the theoretical average number of pages the machine should be used for in a given time period, generally one month.

Maximum Duty Cycle in a LaserPrinter would be the highest number of pages the printer should be used for in a given period of time, again generally one month.

These numbers are more a marketing tool than anything practical.

To determine the actual practical duty cycle of a laser printer you need to know how many pages a toner cartridge is good for and how often a maintenance kit needs to be installed. I can cite one example where a customer printed over 1,000 pages a day on a particular laser printer, the machine required service every 6 months, but had over 1,000,000 pages on it the last time I serviced it. The OEM specifies the duty cycle of that printer at 65,000 pages a month, so the customer was using the machine at half its potential, but, if the machine had been used at its full rated duty cycle, a maintenance kit would have to be installed every 3 months. (list price on that kit is $295, the printer sold for around $1,000)


In the equation:

   duty cycle = t/T x100


   D is the Duty Cycle (% when the signal is active or max peak) 
   t is the duration that the function is non-zero (in one cycle or period only)
   Τ is the period of the function.

Ej: In ones period of 6sec The LED brights for 2sec.

   Duty Cycle= 2s/6s x 100 = .333x100 = 33.3%
   Duty Cycle= 33.3% (the LED brights 1/3 of the time in each period)

"D" does not occur in the equation, and tau does not occur in the "where" explanation, nor in the figure.

Further " D is the duration that the function is non-zero" in nonsensical.

Can we get an improvement? Thank you!

Hans Leander

This should now be better, please feel free to edit the article to improve it further. - CyrilB 19:43, 23 June 2006 (UTC)

Duty cycle is appicable to only square wave form or other forms also?

  • This equation and its description doesn't make much sense to me either. Although, I do not know exactly what the duty cycle of a periodic function really means. I have a program which can create a triangle wave, and it has a function to manipulate the duty cycle of the triangle wave. It basically changes the slope of the wave:

duty cycle = 0 |\|\|\|\|\|\|\|\|\|\

duty cycle = 0.5 /\/\/\/\/\/\/\/\/\/\

duty cycle = 1 /|/|/|/|/|/|/|/|/|/|

(pardon the cheesy ascii graphics)

The description of duty cycle in this article is obviously incomplete and needs to be altered by an expert. 23:00, 9 April 2007 (UTC)

The article on duty cycles appears substantially accurate. In a general sense, “duty cycle” is simply the proportion of any time period for which an apparatus is active. For example, to generate the desired speed for an electric pencil sharpener, the supply of voltage to the sharpener’s electric motor might be limited to specific intervals of time. The electric motor might only receive voltage 60% of the time. The “duty ratio” for this electric motor is said to be 60%. By increasing the percentage of time a motor receives voltage, greater speeds can be achieved.

One method for achieving a desired duty ratio utilizes periodic signals, such as the “sawtooth” signals that your program generates. Although labeled as “duty ratio” by your program, it is more accurate to say that these sawtooth signals are used in the derivation of a duty ratio. These signals, when used with a MOSFET, or other similar component, are logically compared against a “control voltage.” If the sawtooth signal is less than the control voltage, then the electric motor receives voltage. If the sawtooth signal is greater than the control voltage, then voltage to the motor is cut off. In this manner, the electric motor will only be active for a period of the time - - hence, its duty ratio.


As an electronic engineer I would largely agree with the comment immediately above. Whilst you may refer to the duty cycle of a sawtooth waveform or control signal of any system as the period for which it is "active" you would effectively be talking about it in a binary sense, either "active" or "inactive". For a non binary/logic signal the threshold/control level needs to be defined; In the sawtooth example given it seems that you are comparing to a threshold level of zero, but if a different threshold is given then the resulting duty cycle would be different also. Duty cycle is generally used to describe logic signals and a non binary/logic signal should be converted to this form by comparison with a fixed reference before the duty cycle can be defined.

factual dispute?[edit]

While I see discussion of incompleteness I see no discussion of current factual dispute. I have therefore removed the dispute tag from the article in the course of grammatical clean-up. If you have some actual factual dispute with this article, then please reapply the tag and leave a note on the discussion page (with a subject, omg!) Phlake 22:27, 14 August 2007 (UTC)

Duty cycle could be applied to almost anything with on and off states, and is not generally applied to any other waveforms (as has been pointed out earlier in this discussion, where any duty cycle would have to be derived from setting a threshold). Not until I started reading this page and the one on switched mode power supplies have I ever heard the phrase "duty ratio."

I think this is pretty much complete, and I'm not sure we need the "needs attention from an expert" tag any more.

I agree that that article seems relatively complete. Remember that this is an open source encyclopedia and if someone wants expert information on the subject, they will likely have to consult a text in order to have proper references. As far as a common knowledge goes, the article as it stands is plently. ( (talk) 17:24, 17 January 2008 (UTC))

Re: duty cycle and sinusoidal waveforms

sadly, I DO hear "duty cycle" used occasionally when describing sinusoidal brain oscillations (such as alpha and theta rhythms)... but I think it's an innaccurate use of the term, as, in the case of theta rhythm,there are no on or off states... simply peaks and troughs. There also are data suggesting that, during memory formation in the limbic system, neural activity on peaks and troughs of theta simply perform different "duties" - so it's never really "off" and has no "off" states. It's an archaic term that isn't a good description of brain oscillations (unless they explicitly have something that functionally may be considered an "off" state, e.g. some neurons have "up" and "down" states, so if the down state makes a neuron unresponsive, that may be defined effectively as an "off" state, and the term duty cycle could apply). But I avoid it... it irritates me. I still see it used correctly with physiology studies(see Burke RE (2008) Local duty cycle and muscle spindle density. Brain Res Bull. 2008 Mar 28;75(5):501. Epub 2007 Oct 29), where it applies, but with brain oscillations, it makes me think of the guys who look like they're from Bell Labs (circa 1963), complete with short sleeve white shirts and horned rimmed glasses... —Preceding unsigned comment added by (talk) 23:48, 13 April 2008 (UTC)

It makes no sense to have work ratio redirect here. 16:11, 31 May 2009 (UTC) —Preceding unsigned comment added by Younge1986 (talkcontribs)


De gustibus non est disputandum but this reference may look more professional. If you care ....--Bougainville (talk) 00:35, 30 June 2008 (UTC)

Duty ratio in locomotion ?[edit]

The duty ratio seams to be an important parameter when studying artificial/robotic locomotion... but no mention in the article ? XApple (talk) 15:47, 5 January 2009 (UTC)

Huh? Welding for 2 seconds?[edit]

For no apparent reason (which math hounds prolly understand) the example period changed from minutes to seconds. At first glance it appears to claim that an arc welder with 20% duty cycle must run two seconds on, then 8 seconds off.

In equipment such as a welding power supply, the maximum duty cycle is defined as the percentage of time in a 10 minute period that it can be operated continuously before overheating.[6] ............ snip........Based on this analysis the signal is 1 V for 0<t<2 and 0 V for 2<t<10, therefore the period is T= 10 seconds, and the duty cycle is then ON/Period of the signal i.e., 2/10 = 0.2, which gives a duty cycle of 20%

Wasn't period already industry-standardized at 10 minutes? So why the swap? (I'm not questioning the arithmetic, just the communication device.) Why any mathy stuff at all here?

I'm removing this, perhaps it can be made more realistic?

For example, let's say a DC signal of 1 volt starts at time t=0 seconds, and stays there for t=2 seconds, at which point the DC signal goes to 0 volts and stays there until t=10 seconds. At time t = 10 the signal goes back to 1 volt, and the process repeats over and over again. Based on this analysis the signal is 1 V for 0<t<2 and 0 V for 2<t<10, therefore the period is T= 10 seconds, and the duty cycle is then ON/Period of the signal i.e., 2/10 = 0.2, which gives a duty cycle of 20%

-- (talk) 23:54, 25 August 2011 (UTC)Doug Bashford

Duty cycle in biology[edit]

Although the term, "duty cycle," has its origins in engineering, it is also used by many physiologists to analyze biological data such as muscle contraction and bursting by neurons. Therefore, I would like to propose broadening the scope of this article to include living systems, a section on biological data, and to omit "in engineering" at the beginning of the first sentence. Comments welcome. danielkueh (talk) 16:58, 16 December 2011 (UTC)