Reduce power of a microwave oven?

[William Sommerwerck]

If your description is correct, the oven is grossly misdesigned.
You do not implement variable power by turning the magenetron
on for 15 seconds, then letting it sit for a minute! I've /never/ seen
a microwave oven that works that way. My home GE works fine...

Huh? Virtually all the ones I've seen do just that: run a 10 to 15
second on/off time cycle. The magnetron is turned on with a relay, so
rapid cycling just begs to blow that relay.

I could easily test this with frozen bagels. Do you want me to? I'm not much
in the mood.

 

[Jeff Layman]

On 19/01/2011 06:39, Dave Platt wrote:

In article<ih5hng$bfu$1@news.eternal-september.org>,
mike<spamme9@gmail.com> wrote:

Yep, that's the way most of 'em work. The problem is the filament in
the magnetron. Much shorter and you don't get any power out cause
the filament ain't hot yet. With enough mass inside the oven, it
averages out pretty well. For a single frozen hamburger at 1100W, not
so much.

Yes, you can buy a microwave with fine-grained setting of continuous
power at most any retailer...for 3X the price.
They have to keep the filament hot while reducing the power. Much more
complicated and not a commodity item>> much higher price.

Not that much higher these days, I think. The Toshiba "inverter"
microwave ovens have a variable power level of this general sort, and
they're commodity items to the extent of being buyable at Costco and
probably other big-box stores. They're somewhat more expensive than
ovens fixed-power magnetrons, but not all that much.

However... I had one, and it died within a couple of years in home
use. Our previous microwave had lasted for a couple of decades. I'm
not sure whether this was an odd failure in this unit, or was
characteristic of Toshiba inverter microwaves in general, or just an
result of the "race to the bottom, in price and in quality" which
seems to be affecting the whole consumer-electronics business these
days.

I bought a fixed-power-output commercial-service Amana as a
replacement, in the hopes that it'll last rather longer than the
Toshiba did.

My Panasonic has an inverter. Works OK, and and an energy meter

confirmed that it doesn't just cycle from full power to off when running
at lower power levels.

But it does tempt you to experiment. Even though the guidebook warns
against trying to "boil" a perfectly cooked egg in its shell, I thought
it worth trying using lower power levels. The first egg was perfect,
using a rather complicated cooking schedule. The second was very soft -
barely cooked. The third I'd rather forget, but it took a long time to
clean the oven, and SWMBO wasn't amused as she was standing almost next
to the door when it was blown open. It also took me some time to repair
the safety lock...

--

Jeff

 

[Michael A. Terrell]

PeterD wrote:

On Tue, 18 Jan 2011 20:35:49 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:


mike wrote:

My 27 year old microwave oven was down below 400W output and taking a long
time to heat my coffee.
So, I went out and bought a 1100W one.
Big mistake.
It works fine on coffee, but WAY overcooks small stuff.
Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.
I tried to heat a frozen hamburger patty. It boils the liquid around
the outside for 15 seconds, but the inside is still frozen.
This really messes up the cheese stuck to it. If I leave it in
the frozen burger, it comes out awful.

What are my options for reducing power?
Yes, I can stick in a pot of water to absorb energy, but I'm
looking for a more elegant solution.
I assume there's nothing I can do on the primary side, cause of the
filament voltage requirements.
Assuming I can find a switch that can take the voltage and current,
can I switch the value of the big cap? Not much else in there to play with.

Alternatively, there's stuff they put in the bottom of microwave popcorn
that heats up from microwaves. What is that stuff? Maybe I can find a
pan with that in the bottom to average out the energy over time.
There's a "as seen on TV" serving plate that you heat in the microwave.
It's made of granite. What is it in the granite that gets heated?
IF I could find a square of floor tile in ceramic or granite, ceramic is
more easily available, I could stick one of them in the bottom of the oven.

Suggestions?


RTFM to see how to set the cook power.

Or use the defrost cycle!

Why do things right, when you can whine online? ;-)


--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

 

[Michael A. Terrell]

mike wrote:

Michael A. Terrell wrote:
mike wrote:
My 27 year old microwave oven was down below 400W output and taking a long
time to heat my coffee.
So, I went out and bought a 1100W one.
Big mistake.
It works fine on coffee, but WAY overcooks small stuff.
Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.
I tried to heat a frozen hamburger patty. It boils the liquid around
the outside for 15 seconds, but the inside is still frozen.
This really messes up the cheese stuck to it. If I leave it in
the frozen burger, it comes out awful.

What are my options for reducing power?
Yes, I can stick in a pot of water to absorb energy, but I'm
looking for a more elegant solution.
I assume there's nothing I can do on the primary side, cause of the
filament voltage requirements.
Assuming I can find a switch that can take the voltage and current,
can I switch the value of the big cap? Not much else in there to play with.

Alternatively, there's stuff they put in the bottom of microwave popcorn
that heats up from microwaves. What is that stuff? Maybe I can find a
pan with that in the bottom to average out the energy over time.
There's a "as seen on TV" serving plate that you heat in the microwave.
It's made of granite. What is it in the granite that gets heated?
IF I could find a square of floor tile in ceramic or granite, ceramic is
more easily available, I could stick one of them in the bottom of the oven.

Suggestions?


RTFM to see how to set the cook power.

Amazing!!!
RTFM reply when I stated EXACTLY how the power setting works.
How about RTFOP?

Then stick a damn glass of water in the oven to adsorb some of the
energy.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

 

[Wild_Bill]

I suppose the issue could go round 'n round (usenet style), but the term
cooked means different things in different contexts.

Not raw.. safe to eat.
Beef color changed from pink to grey.
Internal temp of 180 F.

Cooked, meaning not raw, is hardly properly prepared to taste. A piece of
beef could be boiled to an internal temp of 180 F, and it's cooked, but I
wouldn't care to eat it prepared that way.. some people do.

If beef doesn't sear from being in contact with blazing hot air/reflected IR
heat (real oven), metal and/or fire, ya might as well be eating soy.
Beef roasted in a real oven will brown on the top/outside, but not in a
typical MWO.

For my tastes, the searing/browning of meats is what gives them good flavor,
not so much the seasoning.. with a few exceptions, fried chicken, for
example.

I prefer real oven or covered grill baked potatoes (or roasted in hot coals)
over microwaved potatoes.. it's a matter of preference. I haven't been able
to get crispy skins in a MWO.
Sure, the MWO potatoes are edible, but far less flavorful.

Many MWO dishes are pre-cooked processed stuff anyway.. not good food when
taken out of the package, but better when eaten warm/hot.

--
Cheers,
WB
..............


"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:7qEZo.371$S16.147@newsfe20.ams2...

I seem to remember that we had this discussion once before some years
back. It depends on how you define the word "cook". Using the traditional
definition of 'preparing food by use of heat' I would contend that this is
exactly what a microwave oven does - or am I missing something ... ? If I
am, then what *is* cooking that a conventional oven does differently ?

Arfa

 

[David Nebenzahl]

On 1/19/2011 9:24 AM William Sommerwerck spake thus:

Oddly, the Wikipedia article claims that microwave cooking heats food more
evenly than any other method, when, in fact, it heats from the outside in,
as does every other cooking method, and can be extremely uneven, if part of
the dish is sitting in a standing-wave node.

.... which should give further pause to those who claim that Wikipedia is
full of good, accurate information ...


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

 

[mike]

Michael A. Terrell wrote:

mike wrote:
Michael A. Terrell wrote:
mike wrote:
My 27 year old microwave oven was down below 400W output and taking a long
time to heat my coffee.
So, I went out and bought a 1100W one.
Big mistake.
It works fine on coffee, but WAY overcooks small stuff.
Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.
I tried to heat a frozen hamburger patty. It boils the liquid around
the outside for 15 seconds, but the inside is still frozen.
This really messes up the cheese stuck to it. If I leave it in
the frozen burger, it comes out awful.

What are my options for reducing power?
Yes, I can stick in a pot of water to absorb energy, but I'm
looking for a more elegant solution.
I assume there's nothing I can do on the primary side, cause of the
filament voltage requirements.
Assuming I can find a switch that can take the voltage and current,
can I switch the value of the big cap? Not much else in there to play with.

Alternatively, there's stuff they put in the bottom of microwave popcorn
that heats up from microwaves. What is that stuff? Maybe I can find a
pan with that in the bottom to average out the energy over time.
There's a "as seen on TV" serving plate that you heat in the microwave.
It's made of granite. What is it in the granite that gets heated?
IF I could find a square of floor tile in ceramic or granite, ceramic is
more easily available, I could stick one of them in the bottom of the oven.

Suggestions?

RTFM to see how to set the cook power.
Amazing!!!
RTFM reply when I stated EXACTLY how the power setting works.
How about RTFOP?


Then stick a damn glass of water in the oven to adsorb some of the
energy.

You're just DETERMINED NOT TO READ the original posting...where I

mentioned that too.
Although, I'd not considered adsorption as a relevant process.

 

[William Sommerwerck]

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4d374867$0$2362$822641b3@news.adtechcomputers.com...

On 1/19/2011 9:24 AM William Sommerwerck spake thus:

Oddly, the Wikipedia article claims that microwave cooking heats food
more
evenly than any other method, when, in fact, it heats from the outside
in,
as does every other cooking method, and can be extremely uneven, if part
of
the dish is sitting in a standing-wave node.

... which should give further pause to those who claim that Wikipedia is
full of good, accurate information ...

It is. No one is claiming it's always absolutely perfect.

 

[mike]

PeterD wrote:

On Tue, 18 Jan 2011 20:35:49 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:

mike wrote:
My 27 year old microwave oven was down below 400W output and taking a long
time to heat my coffee.
So, I went out and bought a 1100W one.
Big mistake.
It works fine on coffee, but WAY overcooks small stuff.
Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.
I tried to heat a frozen hamburger patty. It boils the liquid around
the outside for 15 seconds, but the inside is still frozen.
This really messes up the cheese stuck to it. If I leave it in
the frozen burger, it comes out awful.

What are my options for reducing power?
Yes, I can stick in a pot of water to absorb energy, but I'm
looking for a more elegant solution.
I assume there's nothing I can do on the primary side, cause of the
filament voltage requirements.
Assuming I can find a switch that can take the voltage and current,
can I switch the value of the big cap? Not much else in there to play with.

Alternatively, there's stuff they put in the bottom of microwave popcorn
that heats up from microwaves. What is that stuff? Maybe I can find a
pan with that in the bottom to average out the energy over time.
There's a "as seen on TV" serving plate that you heat in the microwave.
It's made of granite. What is it in the granite that gets heated?
IF I could find a square of floor tile in ceramic or granite, ceramic is
more easily available, I could stick one of them in the bottom of the oven.

Suggestions?

RTFM to see how to set the cook power.

Or use the defrost cycle!

When I ask a question on line, I go to great lengths to describe the issue
in detail to keep the discussion from running off in all directions.
It rarely works, but I keep hoping that people will actually read the
info before shooting from the hip.

With this, and every other low-end non-inverter microwave oven I've ever
encountered, the power is adjusted by pulsing the magnetron in bursts
of approximately 15 seconds followed by an off-time required to get the
average power you programmed.
The RELEVANT number is the 15 second MINIMUM on-time. Doesn't matter
what buttons you push, you can't get an on-time less than 15 seconds unless
you program a single burst that's shorter.
If 15 seconds is long enough to boil the liquid in part of the payload,
defrosting can make a mess of things.

In this case, the "defrost" button has some algorithm that they don't
disclose
and I've been too lazy to reverse-engineer, but the minimum on-time
is still about 15 seconds.
It's a fundamental property of the design.

 

[Lab1]

On 1/19/2011 3:34 PM, William Sommerwerck wrote:

"David Nebenzahl"<nobody@but.us.chickens> wrote in message
news:4d374867$0$2362$822641b3@news.adtechcomputers.com...
On 1/19/2011 9:24 AM William Sommerwerck spake thus:

Oddly, the Wikipedia article claims that microwave cooking heats food
more
evenly than any other method, when, in fact, it heats from the outside
in,
as does every other cooking method, and can be extremely uneven, if part
of
the dish is sitting in a standing-wave node.

... which should give further pause to those who claim that Wikipedia is
full of good, accurate information ...

It is. No one is claiming it's always absolutely perfect.

Reminds me of this interesting video showing how microwave energy is
distributed inside a standard microwave...
http://www.youtube.com/watch?v=kAAXpKdQ-mk

--
-Scott

 

[mike]

Fred McKenzie wrote:

In article <ih536g$rco$1@news.eternal-september.org>,
mike <spamme9@gmail.com> wrote:

Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.
I tried to heat a frozen hamburger patty. It boils the liquid around
the outside for 15 seconds, but the inside is still frozen.

Mike-

Does the new microwave have a Defrost option? If so, does it also cook
for 15 seconds at full power?

I had a small microwave back in the 70s that had a low power setting.
My memory is a little hazy, but I think the low power setting switched a
capacitor in series with the high voltage transformer primary. It acted
as a ballast to reduce magnetron voltage.

Fred
Well, that's what I was asking about.

I don't think there's anything you can do in the primary circuit.
The magnetron filament runs off the same transformer as the high voltage.
If you reduce the average input, you also reduce the average filament
voltage/temperature.
There are two basic issues that I can think of.
1) It takes time for the filament to come up to temperature.
2) The more you thermal-cycle the filament, the shorter the life.
The 15-seconds is a compromise that mostly works.

If you want to pulse the anode, you have to have a separate transformer for
the filament to keep it up to temperature while you pulse the anode.
Conceptually trivial, but it adds to the cost.

As I mentioned in the original posting, you probably can change the value
of the secondary cap, but that takes a high-voltage switch.
I'm interested to learn if anybody's done that. Or if there's
any theoretical basis for concluding that it's a bad idea.

 

[mike]

PeterD wrote:

On Wed, 19 Jan 2011 05:55:03 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

Can you return the oven? You can use the argument
that it's not fit for its intended purpose. Which it isn't.
Nope, my inability to forecast the consequences is not
the fault of the seller.
If your description is correct, the oven is grossly misdesigned. You do not
implement variable power by turning the magenetron on for 15 seconds, then
letting it sit for a minute! I've /never/ seen a microwave oven that works
that way. My home GE works fine, as do all those I've seen where I've
worked.


Huh? Virtually all the ones I've seen do just that: run a 10 to 15
second on/off time cycle. The magnetron is turned on with a relay, so
rapid cycling just begs to blow that relay.
It's worse than that.

A triac can fix the relay issue. The problem is the thermal
time constant of the magnetron filament.

 

[larry moe 'n curly]

mike wrote:

My 27 year old microwave oven was down below 400W output and taking a long
time to heat my coffee.
So, I went out and bought a 1100W one.
Big mistake.
It works fine on coffee, but WAY overcooks small stuff.
Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.

Suggestions?

Put in a smaller high voltage capacitor?

Get an oven with inverter power control, like a Panasonic?

 

[mike]

larry moe 'n curly wrote:

mike wrote:

My 27 year old microwave oven was down below 400W output and taking a long
time to heat my coffee.
So, I went out and bought a 1100W one.
Big mistake.
It works fine on coffee, but WAY overcooks small stuff.
Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.

Suggestions?

Put in a smaller high voltage capacitor?
Thanks for repeating one of my suggested options.

Can you be a little more theoretical?
One reference suggested that the cap is actually
sized to resonate with the transformer. That would make
the change of cap value much more sensitive than just a power
ratio.
Relevant input?
Thanks, mike

Get an oven with inverter power control, like a Panasonic?
Simple matter of price ;-)

 

[William Sommerwerck]

"whit3rd" <whit3rd@gmail.com> wrote in message
news:f2ff7a8b-88eb-47b8-b3d5-1a110939e365@a10g2000vby.googlegroups.com...

The filament winding is on the same transformer as the HV,
so the filament turns off when the transformer isn't powered;
and magnetrons are a diode, it ONLY has the HV electrode
available to control the power.

Ineed, the patent I referred to shows the filament secondary as part of the
main transformer. But the system presumably works.

If there were separate filament and HV transformers, the price
would reflect this 'feature' in unpleasant ways.

I can't imagine a separate filament transformer being /that/ expensive.

 

[whit3rd]

On Jan 19, 5:55 am, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

Yep, that's the way most of 'em work. The problem is the filament in
the magnetron. Much shorter and you don't get any power out cause
the filament ain't hot yet.

I've never heard of varying a magnetron's power by adjusting its filament
voltage! I've always ASS+U+MEd there was some way of turning the tube on and
off by varying an electrode voltage.

The filament winding is on the same transformer as the HV, so the
filament turns off when the transformer isn't powered; and magnetrons
are a diode, it ONLY has the HV electrode available to control the
power.
If there were separate filament and HV transformers, the price would
reflect this 'feature' in unpleasant ways.

 

[whit3rd]

On Jan 19, 2:01 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:

"whit3rd" <whit...@gmail.com> wrote in message

Ineed, the patent I referred to shows the filament secondary as part of the
main transformer. But the system presumably works.

If there were separate filament and HV transformers, the price
would reflect this 'feature' in unpleasant ways.

I can't imagine a separate filament transformer being /that/ expensive.

But, you need to get multikilovolt safety testing on two magnetic
parts,
you need safe wiring in case the 'extra' wires come loose, and you
then require a media campaign to trumpet the added feature, and
a new model number for the finished product, which has to have a
snazzy front-panel rework to distinguish it from the unenhanced
model (which now sells at a different price point)... and the markup
on this $2 technical improvement can easily get you to $120 addon
at the retail store. The marketing department would like that to
be $225.

Yes, it's hard to imagine a separate filament transformer as
expensive.
The marketing department has expert imaginers to do the heavy work
of imagining the price upward. Ever upward. Excelsior!

 

[Fleetie]

mike wrote:

Michael A. Terrell wrote:

Then stick a damn glass of water in the oven to adsorb some of the
energy.

You're just DETERMINED NOT TO READ the original posting...where I
mentioned that too.
Although, I'd not considered adsorption as a relevant process.

You're right: Adsorption is definitely not relevant in this context!


Martin

 

[David Nebenzahl]

On 1/19/2011 12:55 PM mike spake thus:

PeterD wrote:

On Wed, 19 Jan 2011 05:55:03 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

Can you return the oven? You can use the argument that it's
not fit for its intended purpose. Which it isn't.

Nope, my inability to forecast the consequences is not the
fault of the seller.

If your description is correct, the oven is grossly misdesigned.
You do not implement variable power by turning the magenetron on
for 15 seconds, then letting it sit for a minute! I've /never/
seen a microwave oven that works that way. My home GE works fine,
as do all those I've seen where I've worked.

Huh? Virtually all the ones I've seen do just that: run a 10 to 15
second on/off time cycle. The magnetron is turned on with a relay,
so rapid cycling just begs to blow that relay.

It's worse than that. A triac can fix the relay issue. The problem
is the thermal time constant of the magnetron filament.

I guess I'm showing my ignorance here, as I don't know much about
magnetrons, but why can't you just let the filament burn while you cycle
the HV, like you'd do with any other ordinary tube? I mean, with other
tubes, it's OK to apply power to the heater without any anode voltage,
right?


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

 

[Arfa Daily]

"mike" <spamme9@gmail.com> wrote in message
news:ih7ie4$nb5$1@news.eternal-september.org...

PeterD wrote:
On Tue, 18 Jan 2011 20:35:49 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:

mike wrote:
My 27 year old microwave oven was down below 400W output and taking a
long
time to heat my coffee.
So, I went out and bought a 1100W one.
Big mistake.
It works fine on coffee, but WAY overcooks small stuff.
Yes, it has a power level setting, but the on-time is 15 seconds
and they modulate the off-time.
I tried to heat a frozen hamburger patty. It boils the liquid around
the outside for 15 seconds, but the inside is still frozen.
This really messes up the cheese stuck to it. If I leave it in
the frozen burger, it comes out awful.

What are my options for reducing power?
Yes, I can stick in a pot of water to absorb energy, but I'm
looking for a more elegant solution.
I assume there's nothing I can do on the primary side, cause of the
filament voltage requirements.
Assuming I can find a switch that can take the voltage and current,
can I switch the value of the big cap? Not much else in there to play
with.

Alternatively, there's stuff they put in the bottom of microwave
popcorn
that heats up from microwaves. What is that stuff? Maybe I can find a
pan with that in the bottom to average out the energy over time.
There's a "as seen on TV" serving plate that you heat in the microwave.
It's made of granite. What is it in the granite that gets heated?
IF I could find a square of floor tile in ceramic or granite, ceramic
is
more easily available, I could stick one of them in the bottom of the
oven.

Suggestions?

RTFM to see how to set the cook power.

Or use the defrost cycle!

When I ask a question on line, I go to great lengths to describe the issue
in detail to keep the discussion from running off in all directions.
It rarely works, but I keep hoping that people will actually read the
info before shooting from the hip.

With this, and every other low-end non-inverter microwave oven I've ever
encountered, the power is adjusted by pulsing the magnetron in bursts
of approximately 15 seconds followed by an off-time required to get the
average power you programmed.
The RELEVANT number is the 15 second MINIMUM on-time. Doesn't matter
what buttons you push, you can't get an on-time less than 15 seconds
unless
you program a single burst that's shorter.
If 15 seconds is long enough to boil the liquid in part of the payload,
defrosting can make a mess of things.

In this case, the "defrost" button has some algorithm that they don't
disclose
and I've been too lazy to reverse-engineer, but the minimum on-time
is still about 15 seconds.
It's a fundamental property of the design.

All correct by my experience, also

Arfa