generator mufflers

LJ wrote:
Try two hub caps in the shape of a frizz-be(sp).Cut a hole in one cap
and weld it to the top of your exhaust pipe,weld the other cap one or
two inches above the first cap.You won't hear the exhaust.


That sounds very interesting.

But I'm having trouble reconciling "two hubcaps in the shape of a
frisbee."
with the second one welded "one or two inches" above the first.

Do you mean like this:

___
/ \
(gap)
\ _ _ /
| |
| |

(This will look beter with a non-proportionate font.)

--

FF'

Yes.You might experment with the gap. LJ

wrote:

LJ wrote:

Try two hub caps in the shape of a frizz-be(sp).Cut a hole in one cap
and weld it to the top of your exhaust pipe,weld the other cap one or
two inches above the first cap.You won't hear the exhaust.



That sounds very interesting.

But I'm having trouble reconciling "two hubcaps in the shape of a
frisbee."
with the second one welded "one or two inches" above the first.

Do you mean like this:

___
/ \
(gap)
\ _ _ /
| |
| |

(This will look beter with a non-proportionate font.)

"john smith" wrote in message
...
Sine wave, square wave and things inbetween.
It's all about the "area under the curve".
Tim "The Tool Man" Taylor always wanted "more power".
Sometimes, this is not a good thing.
The "power" delivered by cycle, be it square wave, sine wave or things
inbetween, can be found by calculating the area under the curve.
For a square wave, it is simple the width times the height.

That is why I asked about the wave form. I was assured it was sine wave. I
still wonder. Usually they are proud of true sine wave, and advertise it.
--
Jim in NC

"Lou" wrote in message
ups.com...
Jim, too bad you can't hear my applause. That was such a good
explination, I even understood it. Thanks

Thanks. After all I am supposed to be a teacher! :-))
--
Jim in NC

"john smith" wrote

Sine wave, square wave and things inbetween.
It's all about the "area under the curve".

There are methods to reduce the area above the sign wave within the
square wave, but they complicate the inverter design and can add volume
to the packaging.
snip
Pulsewidth modulation, an electronic means of making different length
square waves is an elegant solution, but adds cost and complexity.
snip

The Yamaha is supposed to have pulse width modulation, which if it is fast
enough, can come pretty close to sine wave, I guess.
--
Jim in NC

In article ,
"Morgans" wrote:

The Yamaha is supposed to have pulse width modulation, which if it is fast
enough, can come pretty close to sine wave, I guess.

Powerwise, yes.
As a sinewave arcs up to a peak then arcs down, the pulse widths become
progressively wider then narrower. The average of the area under the
curve approaches the power of of the sinewaveform. A simplified
approximation...
_ __ ___ __ _
| | | | | | | | | |
_| |_| |_| |_| |_| |_

"Morgans" wrote in message
...

That is why I asked about the wave form. I was assured it was sine wave. I
still wonder. Usually they are proud of true sine wave, and advertise it.

From the Yamaha site: "
a.. Inverter System with Pulse Width Modulation - Industry-leading system
produces higher-quality and cleaner electricity. Results in pure sine wave as
clean or cleaner than commercial power and can operate products with built in
microcomputers."
a..
Note the words: " Results in pure sine wave". Yes, it is pwm (just like any
sine wave inverter I know of), but the resultant waveform is far cleaner than
you will get from most any other generator, particularly from any other consumer
grade generator.

If you look closely at the specifications & instructions that come with cheap
generators, you will often see verbage warning you about operating sensitive
equipment. This is because they can have distorted waveforms, off-frequency
operation, and poor voltage regulation. (That said, they often manage to do the
job amazingly well.)

This conversation started about refrigeration motors which can be quite fussy
about waveform, but it is little understood that modern electronics have
switching power supplies that can be pretty insensitive to waveform. Strangely,
your computer is more likely to run well off of your cheap inverter than your
refrigerator, even though both of them may require about the same wattage.

Vaughn



--
Jim in NC

In article
,
"Vaughn Simon" wrote:

This conversation started about refrigeration motors which can be quite fussy
about waveform, but it is little understood that modern electronics have
switching power supplies that can be pretty insensitive to waveform.
Strangely,
your computer is more likely to run well off of your cheap inverter than your
refrigerator, even though both of them may require about the same wattage.

(I am trying to remember all this from college physics)
Think about how a refridgeration system "starts" and runs.
There is usually a "start-run" capacitor.
The capacitor is a "voltage" device.
The motor to run the compressor is a "current" device.
ELI ICE
Voltage leads current in an inductor (motor) by 90-degrees
Current leads voltage in a capacitor by 90-degrees

This has to do with the current and voltage phase with respect to each
other. This is really neat to watch on an oscilliscope.
Draw a picture of two sinewaves, shifted by 1/4-wavelength.
As you start up the compressor, the motor draws a slug of current, so
the sinewave current waveform distorts to look something like a sharks
fin. As the current gets sucked into the wires of the inductor, the
voltage collapses. The start-run capacitor dumps its stored voltage to
hold the line voltage up until the current draw diminishes as the
magnetic field is established. Then the capacitor draws a slug of
voltage to recharge itself, and the voltage waveform takes on the
sharkfin shape. And then the process repeats itself.
(Does that sound right to the experts out there?)