Re: Not sure you rember me.


"John H." <salmonbait@xxxxxxxxxxxxxxx> wrote in message
news:3ced4413al1re498u88nb843dak32gdddg@xxxxxxxxxx
On Wed, 4 Jun 2008 04:24:54 -0700 (PDT), JamesGangNC@xxxxxxxxx wrote:

On Jun 4, 6:54 am, John H. <salmonb...@xxxxxxxxxxxxxxx> wrote:
On Wed, 04 Jun 2008 06:35:02 -0400, sa...@xxxxxxx wrote:
On Tue, 3 Jun 2008 21:27:02 -0400, "Jim" <j...@xxxxxxxxxxx> wrote:

"DK" <intrcep...@xxxxxxxxxxxx> wrote in message
news:ktCdnURnFNTpRtjVnZ2dnUVZ_gudnZ2d@xxxxxxxxxxxxxxx
LoogyPic...@xxxxxxxxx wrote:
On Jun 2, 10:43 pm, "jamesgangnc" <ja...@xxxxxxxxxx> wrote:
Actually fish finders do draw a fair amount of current, just not
continuously. How do you think they have 600 watt transducers?

Apples and oranges. I'd be shocked if his duty cycle is above 30
watts.
My Hummingbird has a 2.5 amp fuse, btw.

So that's 240 volts. You have one hell of a battery!

Shouldn't we be thinking of duty cycle in terms of percent or ratio?

Loogy picked up on my use of the term, but he doesn't know what duty
cycle IS.
DK just took Loogy's error and compounded it with another one.

When I looked up 'duty cycle' on Wikipedia, it was given as a percent or
fraction:

"In telecommunications and electronics, the term duty cycle is used to
describe the fraction of time that a system is in an "active" state. In
particular, it is used in the following contexts:
The duty cycle D is defined as the ratio between the pulse duration (?)
and
the period (T) of a rectangular waveform
The duty cycle D is defined as the ratio between the pulse duration (?)
and
the period (T) of a rectangular waveform

Duty cycle is the proportion of time during which a component, device,
or
system is operated. Suppose a disk drive operates for 1 second, and is
shut
off for 99 seconds, then is run for 1 second again, and so on. The drive
runs for one out of 100 seconds, or 1/100 of the time, and its duty
cycle
is therefore 1/100, or 1 percent.

In a periodic phenomenon, the ratio of the duration of the phenomenon in
a
given period to the period."

How about enlightening us non electrical engineers as to just what it
is?

--
John *H*- Hide quoted text -

- Show quoted text -

In this specific case of fish finders and radar the duty cycle is the
percentage of time it is generating a pulse. A 600 watt fish finder
does not use 600 watts all the time. It sends 600 watt pulses. Then
it listens to the pulse. Since it has to wait for it to return from
the farthest range of the device it is probably listening a lot more
that it is generating.

A 600 watt pulse would require 50 amps if it was generated straight
from 12 volts. Watts equals volts times amps. But in reality the
internal power supply is accumulating power, probably at a higher
voltage, in preparation to generate the pulse. The load on the 12
volt side is most likely pretty constant but there may be a cycle of
surges associated with charging up to prepare to generate the pulse.
The only way to know for sure would be to put a scope on it.

Well, that makes good sense, but from what you said, the 'duty cycle'
would
still be the percent of time the pulse is being produced. True?
--
John *H*

True. Duty Cycle % = (on time / total time)*100. Airborne radar units on
the transports I worked on put out 50KW at a 2% duty cycle. It transmitted
a very powerful, very short pulse and then had to wait enough time for the
pulse to go out 150 miles and then return minimum. So you were only drawing
about a 1000 watts from the airplanes power system. Lot of power actually
but the generators could supply it. Think about the size of a 1000 W Honda
Generator. Not very big, including the motor.


.

Relevant Pages

  • Re: Not sure you rember me.
    ... the term duty cycle is used to ... The duty cycle D is defined as the ratio between the pulse duration and ... A 600 watt fish finder ... Watts equals volts times amps. ...
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  • Re: Not sure you rember me.
    ... the term duty cycle is used to ... The duty cycle D is defined as the ratio between the pulse duration and ... A 600 watt fish finder ... Watts equals volts times amps. ...
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  • Re: Not sure you rember me.
    ...  How do you think they have 600 watt transducers? ... The duty cycle D is defined as the ratio between the pulse duration and ... Battery cycle describes a complete discharge and recharge cycle. ...
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  • Re: Not sure you rember me.
    ... the term duty cycle is used to ... The duty cycle D is defined as the ratio between the pulse duration and ... A 600 watt fish finder ... Watts equals volts times amps. ...
    (rec.boats)
  • Re: Not sure you rember me.
    ...  How do you think they have 600 watt transducers? ... My Hummingbird has a 2.5 amp fuse, ... The duty cycle D is defined as the ratio between the pulse duration and ...
    (rec.boats)
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