Can a microwave oven have its output imited?

[mm]

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time. The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)

 

On Sat, 14 May 2011 14:35:51 -0400, mm <NOPSAMmm2005@bigfoot.com>
wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time. The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)

The "power control" is a "per cent on" control. 90% for one minute
means the unit runs at full power for .9 * 60 seconds or 54 seconds,
usually in semi-equal segments such as on 18 seconds, off 2 seconds or
on 9 seconds, off 1 second.

John

 

[Michael A. Terrell]

mm wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

Can you write code for the microprocessor in the control panel? The
power function is hard coded into the controller.

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time.

That is a form of 'Pulse Width Modulation'.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

 

[mm]

On Sat, 14 May 2011 16:35:53 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

mm wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

I can see how this is ambiguous.

Is there any chance I can turn the full power down by 10%, for every
use?


Can you write code for the microprocessor in the control panel? The

No.

power function is hard coded into the controller.

I didn't have in mind changing the power function, but changing the
circuit that makes the microwaves. Maybe at the stage at or just
before the microwave tube. So they would be weaker. By changing
the bias on the output transistor, or something like that. I was
hoping there might be a pot there already.

The power function would still work, turning the radiation on X% of
the time and off 100-X% of the time.

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time.


That is a form of 'Pulse Width Modulation'.

Good to know.

Thanks.

 

[Michael A. Terrell]

mm wrote:

On Sat, 14 May 2011 16:35:53 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:


mm wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

I can see how this is ambiguous.

Is there any chance I can turn the full power down by 10%, for every
use?


Can you write code for the microprocessor in the control panel? The

No.

power function is hard coded into the controller.

I didn't have in mind changing the power function, but changing the
circuit that makes the microwaves. Maybe at the stage at or just
before the microwave tube. So they would be weaker. By changing
the bias on the output transistor, or something like that. I was
hoping there might be a pot there already.

Magnetrons don't work that way. They run at full power over their
useful life. That's why they have to use PWM to control the average
power level.

The power function would still work, turning the radiation on X% of
the time and off 100-X% of the time.


(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time.


That is a form of 'Pulse Width Modulation'.

Good to know.

Thanks.

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

 

[mm]

On Sat, 14 May 2011 19:19:28 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

mm wrote:

On Sat, 14 May 2011 16:35:53 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:


mm wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

I can see how this is ambiguous.

Is there any chance I can turn the full power down by 10%, for every
use?


Can you write code for the microprocessor in the control panel? The

No.

power function is hard coded into the controller.

I didn't have in mind changing the power function, but changing the
circuit that makes the microwaves. Maybe at the stage at or just
before the microwave tube. So they would be weaker. By changing
the bias on the output transistor, or something like that. I was
hoping there might be a pot there already.


Magnetrons don't work that way. They run at full power over their
useful life. That's why they have to use PWM to control the average
power level.

Makes sense. Okay. I'll give up the plan. That's one more thiing I
don't have to do.

Thanks again.

The power function would still work, turning the radiation on X% of
the time and off 100-X% of the time.


(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time.


That is a form of 'Pulse Width Modulation'.

Good to know.

Thanks.

 

[Jim Yanik]

news@jecarter.us wrote in news:5amts6tjf51af0o441uos43hpsfo3r1e0i@4ax.com:

On Sat, 14 May 2011 14:35:51 -0400, mm <NOPSAMmm2005@bigfoot.com
wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time. The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)

The "power control" is a "per cent on" control. 90% for one minute
means the unit runs at full power for .9 * 60 seconds or 54 seconds,
usually in semi-equal segments such as on 18 seconds, off 2 seconds or
on 9 seconds, off 1 second.

John

UNLESS you buy an inverter oven,that can actually regulate the power
delivered to the magnetron.(and thus it's output power)
but you still have to program that each time you use the oven.

--
Jim Yanik
jyanik
at
localnet
dot com

 

[Michael A. Terrell]

mm wrote:

On Sat, 14 May 2011 19:19:28 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:

Magnetrons don't work that way. They run at full power over their
useful life. That's why they have to use PWM to control the average
power level.

Makes sense. Okay. I'll give up the plan. That's one more thiing I
don't have to do.

Thanks again.

You're welcome. That's why I have two microwave ovens.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

 

[GS]

On May 14, 8:49 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:

mm wrote:

On Sat, 14 May 2011 19:19:28 -0400, "Michael A. Terrell"
mike.terr...@earthlink.net> wrote:

  Magnetrons don't work that way.  They run at full power over their
useful life.  That's why they have to use PWM to control the average
power level.

Makes sense.  Okay.  I'll give up the plan.  That's one more thiing I
don't have to do.

Thanks again.

   You're welcome.  That's why I have two microwave ovens.

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

I use two. A big sears 800 watts, and little Panasonic inverter 1200
watts. Weird but true. Always use the inverter for frozen dinners.

I think you have to wide pulse the magnetron, like many seconds.
A little weird, the inverter takes about 3 seconds to fire up after
pushing start.

Greg

 

[mike]

news@jecarter.us wrote:

On Sat, 14 May 2011 14:35:51 -0400, mm <NOPSAMmm2005@bigfoot.com
wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time. The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)

The "power control" is a "per cent on" control. 90% for one minute
means the unit runs at full power for .9 * 60 seconds or 54 seconds,
usually in semi-equal segments such as on 18 seconds, off 2 seconds or
on 9 seconds, off 1 second.

John
I've got the same problem, but need more like 50%.

I'd considered adding another cap at half the value.
Not sure how to to the HV switching safely with affordable
components.

 

[Michael A. Terrell]

GS wrote:

On May 14, 8:49 pm, "Michael A. Terrell" <mike.terr...@earthlink.net
wrote:
mm wrote:

On Sat, 14 May 2011 19:19:28 -0400, "Michael A. Terrell"
mike.terr...@earthlink.net> wrote:

Magnetrons don't work that way. They run at full power over their
useful life. That's why they have to use PWM to control the average
power level.

Makes sense. Okay. I'll give up the plan. That's one more thiing I
don't have to do.

Thanks again.

You're welcome. That's why I have two microwave ovens.

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

I use two. A big sears 800 watts, and little Panasonic inverter 1200
watts. Weird but true. Always use the inverter for frozen dinners.

I think you have to wide pulse the magnetron, like many seconds.
A little weird, the inverter takes about 3 seconds to fire up after
pushing start.

The Magnatron filament is turned on and off to pulse the output. It
takes a fraction of a second to warm up.

--
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:

news@jecarter.us wrote:
On Sat, 14 May 2011 14:35:51 -0400, mm <NOPSAMmm2005@bigfoot.com
wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time. The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)

The "power control" is a "per cent on" control. 90% for one minute
means the unit runs at full power for .9 * 60 seconds or 54 seconds,
usually in semi-equal segments such as on 18 seconds, off 2 seconds or
on 9 seconds, off 1 second.

John
I've got the same problem, but need more like 50%.
I'd considered adding another cap at half the value.
Not sure how to to the HV switching safely with affordable
components.

Just program the cook power, or get a smaller oven. The power supply
in a microwave can kill you in a heartbeat.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

 

[klem kedidelhopper]

On May 15, 5:37 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:

mike wrote:

n...@jecarter.us wrote:
On Sat, 14 May 2011 14:35:51 -0400, mm <NOPSAMmm2...@bigfoot.com
wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV?   Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power.  (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time.  The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)

The "power control" is a "per cent on" control.  90% for one minute
means the unit runs at full power for .9 * 60 seconds or 54 seconds,
usually in semi-equal segments such as on 18 seconds, off 2 seconds or
on 9 seconds, off 1 second.

John
I've got the same problem, but need more like 50%.
I'd considered adding another cap at half the value.
Not sure how to to the HV switching safely with affordable
components.

   Just program the cook power, or get a smaller oven.  The power supply
in a microwave can kill you in a heartbeat.

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

I was just reading this thread and it brought a question to mind. What
if theoretically speaking you dropped the line voltage to the HV
circuit but not the control section? This would reduce both the
filament voltage as well as the HV secondary voltage on the
transformer. The result I would think would be a reduction in output
power, wouldn't it? Lenny

 

[spamtrap1888]

On May 14, 11:35 am, mm <NOPSAMmm2...@bigfoot.com> wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV?   Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power.  (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

Take it back and buy one that puts out the power level your recipes
call for.

But beware: we have an 800 watt oven that used to be compatible with
recipes, but now all the recipes are for 1100 watts.

 

[Michael A. Terrell]

klem kedidelhopper wrote:

On May 15, 5:37 pm, "Michael A. Terrell" <mike.terr...@earthlink.net
wrote:
mike wrote:

n...@jecarter.us wrote:
On Sat, 14 May 2011 14:35:51 -0400, mm <NOPSAMmm2...@bigfoot.com
wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time. The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)

The "power control" is a "per cent on" control. 90% for one minute
means the unit runs at full power for .9 * 60 seconds or 54 seconds,
usually in semi-equal segments such as on 18 seconds, off 2 seconds or
on 9 seconds, off 1 second.

John
I've got the same problem, but need more like 50%.
I'd considered adding another cap at half the value.
Not sure how to to the HV switching safely with affordable
components.

Just program the cook power, or get a smaller oven. The power supply
in a microwave can kill you in a heartbeat.

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

I was just reading this thread and it brought a question to mind. What
if theoretically speaking you dropped the line voltage to the HV
circuit but not the control section? This would reduce both the
filament voltage as well as the HV secondary voltage on the
transformer. The result I would think would be a reduction in output
power, wouldn't it? Lenny

It will stop oscillating, if you reduce them very much.


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.

 

[mike]

Michael A. Terrell wrote:

mike wrote:
news@jecarter.us wrote:
On Sat, 14 May 2011 14:35:51 -0400, mm <NOPSAMmm2005@bigfoot.com
wrote:

Can a microwave oven have its output controlled, limited, by something
like adjusting the AGC on a TV? Or on combo devices, radio,
cassette, CD, tv, there is usually a pot on each of those, adjusted so
the volume stays the same when one changes functions.

I didn't like my old small microwave oven because it was so small, and
I also had to cook longer than instructions said, because it was low
power. (So I was in the habit of mulitplying the time given by 1.1 or
1.3, but I was hoping not to have to do that anymore.)

Now I have a new, one-year old, full-size Sharp microwave -- I can
provide the model number if it matters -- and it is too powerful.
Things cooked in their packages according to instructions have their
water boiling over and taking some of the food with it, and I presume
other food is being cooked more than instructions or recipes call for.

It has a power control that will lower the power by 10% for every push
of the button, but I would have to use that button every time.

Is there any chance I can turn the full power down by 10%, for every
use?

(As an aside, it's interesting that on 90% power, for example, I can
tell when the microwave part is functioning because it makes more
noise during the 90% than the 10% of the time. The old no-name-brand
only had one other power level, Defrost, but it made the same noise
all the time, and to see how much of the time it was making heat, I
had to turn on a nearby AM radio and tune to a weak or no station, and
listen to the radiation from the microwave.)
The "power control" is a "per cent on" control. 90% for one minute
means the unit runs at full power for .9 * 60 seconds or 54 seconds,
usually in semi-equal segments such as on 18 seconds, off 2 seconds or
on 9 seconds, off 1 second.

John
I've got the same problem, but need more like 50%.
I'd considered adding another cap at half the value.
Not sure how to to the HV switching safely with affordable
components.


Just program the cook power,
Cook power doesn't help 'cause it stays on for 15 seconds at a time

at most settings. You can easily ruin stuff by overcooking it 15
seconds at a time.
or get a smaller oven.
If I'd wanted a smaller oven, I'd have bought a smaller oven.
I shoulda bought an inverter, but the cost was prohibitive.

The power supply

in a microwave can kill you in a heartbeat.
Yep, that's why I used the word "safely".

 

[Jim Yanik]

Cydrome Leader <presence@MUNGEpanix.com> wrote in
news:iqrnjj$7ss$1@reader1.panix.com:

Michael A. Terrell <mike.terrell@earthlink.net> wrote:

GS wrote:

On May 14, 8:49 pm, "Michael A. Terrell"
mike.terr...@earthlink.net> wrote:
mm wrote:

On Sat, 14 May 2011 19:19:28 -0400, "Michael A. Terrell"
mike.terr...@earthlink.net> wrote:

Magnetrons don't work that way. They run at full power over
their
useful life. That's why they have to use PWM to control the
average power level.

actually,like any other vacuum tube,power output depends on plate voltage
and current. If you lower the plate voltage,the magnetron WILL produce less
power. that's how the inverter ovens work.

But originally,it was too expensive to control plate voltage,so the
manufacturers went for duty cycle operation instead.("pulsed")
You can do that with a cheap relay and timer circuit.

Now,it's cheaper to use an inverter because the heavy iron transformer
costs so much more than a smaller HF switcher transformer,and a switcher
can control it's output voltage.

Makes sense. Okay. I'll give up the plan. That's one more
thiing I don't have to do.

Thanks again.

You're welcome. That's why I have two microwave ovens.

--
You can't fix stupid. You can't even put a Band-Aid? on it,
because it's Teflon coated.

I use two. A big sears 800 watts, and little Panasonic inverter 1200
watts. Weird but true. Always use the inverter for frozen dinners.

I think you have to wide pulse the magnetron, like many seconds.
A little weird, the inverter takes about 3 seconds to fire up after
pushing start.


The Magnatron filament is turned on and off to pulse the output.
It
takes a fraction of a second to warm up.

Some of the older US made units from Litton or Tappan had a giant reed
relay, and the HV was actually switched on and off for the defrost
mode. They made a nice sound switching on and off.

it's cheaper to switch the transformer side instead of the HV side,and the
HV switching probably wears out quicker.

--
Jim Yanik
jyanik
at
localnet
dot com

 

[William Sommerwerck]

Some of the older US made units from Litton or Tappan had
a giant reed relay, and the HV was actually switched on and
off for the defrost mode. They made a nice sound switching
on and off.

I'm curious as to how my GE works.

If, at 50% (say) you were full "on" for one minute, then off for one minute,
you'd be running in that first minute at a power level that would cause
localized boiling. (This is a problem with soups and oatmeal.)

I do not see that. Therefore, I have (???) to assume that PWM with a cycle
of less than one second is used.

 

[Cydrome Leader]

Michael A. Terrell <mike.terrell@earthlink.net> wrote:

GS wrote:

On May 14, 8:49 pm, "Michael A. Terrell" <mike.terr...@earthlink.net
wrote:
mm wrote:

On Sat, 14 May 2011 19:19:28 -0400, "Michael A. Terrell"
mike.terr...@earthlink.net> wrote:

Magnetrons don't work that way. They run at full power over their
useful life. That's why they have to use PWM to control the average
power level.

Makes sense. Okay. I'll give up the plan. That's one more thiing I
don't have to do.

Thanks again.

You're welcome. That's why I have two microwave ovens.

--
You can't fix stupid. You can't even put a Band-Aid? on it, because it's
Teflon coated.

I use two. A big sears 800 watts, and little Panasonic inverter 1200
watts. Weird but true. Always use the inverter for frozen dinners.

I think you have to wide pulse the magnetron, like many seconds.
A little weird, the inverter takes about 3 seconds to fire up after
pushing start.


The Magnatron filament is turned on and off to pulse the output. It
takes a fraction of a second to warm up.

Some of the older US made units from Litton or Tappan had a giant reed
relay, and the HV was actually switched on and off for the defrost mode.
They made a nice sound switching on and off.

 

[William Sommerwerck]

"Cydrome Leader" <presence@MUNGEpanix.com> wrote in message
news:iqs93v$lv7$1@reader1.panix.com...

William Sommerwerck <grizzledgeezer@comcast.net> wrote:

I'm curious as to how my GE works.

If, at 50% (say) you were full "on" for one minute, then off for one
minute,
you'd be running in that first minute at a power level that would cause
localized boiling. (This is a problem with soups and oatmeal.)

I do not see that. Therefore, I have (???) to assume that PWM with a
cycle
of less than one second is used.

1 second seems pretty excessive. I don't recall what the timing cycle on
the Tappan ones were, but it was less than a minute for sure, but not
every few seconds.

What do you mean by excessive? If a magnetron can be modulated by varying
its B+, why shouldn't each PWM cycle be just one or two seconds long? You DO
NOT want the magnetron running at full power for "long" periods, followed by
even longer periods off (eg, one minute, four minutes off, for 20%).

I really liked those older machines. They were easy to use. I still don't
get why a microwave oven needs multiple buttons pressed to heat food.
It used to just be, turn the timing knob and press start. That's it.

My GE has six instant-start buttons, for one through six minutes.