sci.electronics.repair@googlegroups.com

Today's topics:

* Can a microwave oven have its output imited? - 6 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/956ea2dbdf891e16?hl=en
* a bios question - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/7c0bc6748d91ff8b?hl=en
* Help with wiring colors on old headphones - 13 messages, 8 authors
http://groups.google.com/group/sci.electronics.repair/t/f8481990f5c47309?hl=en
* How to make antenna for a Weather Radio - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/db4f2a9fbbc88e5a?hl=en
* another puzzler - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/b80657d8be4c22cd?hl=en

==============================================================================
TOPIC: Can a microwave oven have its output imited?
http://groups.google.com/group/sci.electronics.repair/t/956ea2dbdf891e16?hl=en
==============================================================================

== 1 of 6 ==
Date: Sat, May 14 2011 1:47 pm
From: 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.

== 2 of 6 ==
Date: Sat, May 14 2011 4:19 pm
From: "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.

== 3 of 6 ==
Date: Sat, May 14 2011 4:21 pm
From: 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.

== 4 of 6 ==
Date: Sat, May 14 2011 5:17 pm
From: 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

== 5 of 6 ==
Date: Sat, May 14 2011 5:49 pm
From: "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.

== 6 of 6 ==
Date: Sat, May 14 2011 6:59 pm
From: 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

==============================================================================
TOPIC: a bios question
http://groups.google.com/group/sci.electronics.repair/t/7c0bc6748d91ff8b?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, May 14 2011 2:21 pm
From: Bob Villa

On May 14, 3:30 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:
> Bob Villa wrote:
>
> > On May 14, 7:41 am, "Michael A. Terrell" <mike.terr...@earthlink.net>
> > wrote:
> > > Bob Villa wrote:
>
> > > > On May 14, 2:47 am, "Michael A. Terrell" <mike.terr...@earthlink.net>
> > > > wrote:
>
> > > > >...and some of my ideas made it into space.
>
> > > > I think we have all heard that many times. If you were half as smart
> > > > as you think...you wouldn't have bothered to respond, would you?
> > > > You remind me of another anal retentive engineer BillW50. God checks-
> > > > in with him also...when He's stumped!
>
> > >    Don't you have a plugged up toilet calling for your expert help?
>
> > If you're the same "Michael A. Terrell, Jr." that works for Chrysler I
> > pity you if your bosses see how immature you are in your responses
> > here.
>
>    If you think it's me, tell Chrysler about it.  Of course, if you
> actually knew anything about computers you would know what part of the
> county I'm in, junior.
>
> > This surely applies to you.."I'm a strong relationship builder with
> > solid leadership skills."  From your LinkedIn.
>
>    I see your search skill suck, too.  Typical of a low grade troll, who
> brags about doing substandard repairs.
>
> --
> You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
> Teflon coated.

How about Deland,Fla? Like there is any skill involved, Mr, Infantile!

== 2 of 2 ==
Date: Sat, May 14 2011 4:42 pm
From: "Michael A. Terrell"

Bob Villa wrote:
>
> On May 14, 3:30 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
> wrote:
> > Bob Villa wrote:
> >
> > > On May 14, 7:41 am, "Michael A. Terrell" <mike.terr...@earthlink.net>
> > > wrote:
> > > > Bob Villa wrote:
> >
> > > If you're the same "Michael A. Terrell, Jr." that works for Chrysler I
> > > pity you if your bosses see how immature you are in your responses
> > > here.
> >
> > If you think it's me, tell Chrysler about it. Of course, if you
> > actually knew anything about computers you would know what part of the
> > county I'm in, junior.
> >
> > > This surely applies to you.."I'm a strong relationship builder with
> > > solid leadership skills." From your LinkedIn.
> >
> > I see your search skill suck, too. Typical of a low grade troll, who
> > brags about doing substandard repairs.
>
> How about Deland,Fla? Like there is any skill involved, Mr, Infantile!

Right state, but I haven't been near Deland since my last trip to the
WACX transmitter site, over 20 years ago. They had a fairly new Comark
transmitter and 1700' plus tower. The only repairs the transmitter
needed was to replace a defective spark detector on one of the three 65
KW EEV Klystrons, and a couple bulbs in the meters. The Umatic tape
decks were the attention whores, and they like to die on holidays.

I give you three points for trying, but you lost two points for a bad
attitude. You could save yourself a lot of embarrassment if you didn't
post so much ignorant crap, like "Works for Chrysler". I'm retired,
after 45 years of working in electronics. You have yet to prove
yourself to anyone on this group, so keep shooting off your toes, till
you have nothing left to stand on. I have been here since 1997, and
have used this account since 2003. I had to drop the first ISP when I
moved, and found that they didn't offer service at my new house.

<http://groups.google.com/group/sci.electronics.repair/browse_thread/thread/bb71791d7eea4210/c07c05f031e4b9e2?lnk=gst&q=#c07c05f031e4b9e2>

You popped up recently with a bad attitude and haven't shut up
since. Keep calling people names like 'Mr, Infantile!' and everyone
using a real NNTP server will just kill file you. Then all you will
have are other Google Gropers to insult.

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

==============================================================================
TOPIC: Help with wiring colors on old headphones
http://groups.google.com/group/sci.electronics.repair/t/f8481990f5c47309?hl=en
==============================================================================

== 1 of 13 ==
Date: Sat, May 14 2011 2:32 pm
From: Fleetie

Patrick wrote:
> On 13:49 14 May 2011, Phil Allison wrote:
>
>> "Patrick = another PITA Jerk
>>> Out of phase headphone transducers create a far more subtle adverse
>>> effect than that noticed in loudspeakers, so it is not something
>>> immediately evident by A-B testing.
>>
>> ** That is 100% fucking BULLSHIT !!!!!!!!!
>>
>> With any mono signal, the difference is HUGE.
>
> There is no phase cancellation like there is for speaker sounds because the
> sound from each headphone transducer is interfereing with the other.

Wrong, I'm afraid. I myself have heard a 2-channel sound clip on the net that
irrefutably demonstrated that interference does occur in the brain, at
lowish frequencies, but not that low. Up to a few hundred Hz.

It was a clip of (f Hz) in one channel/earphone, and (f+delta Hz) into
the other earphone.

With just either (one) earphone inserted, you could hear just a plain tone of
f or (f+delta) as expected.

With both in, you heard the beating at a few Hz, proving that addition/
mixing was taking place in the brain.

It sounded very weird, and I was very surprised. but the effect was utterly
obvious and undeniable.

I can't remember now where I found the sound sample, but IIRC it was a link
on Wikipedia.

Martin

== 2 of 13 ==
Date: Sat, May 14 2011 2:33 pm
From: Fleetie

Patrick wrote:
> I have some vinatge headphones (Sennheiser HD424) and want to attach a new
> plug.
>
> Which color wires are the positive ones?
>
> The colors in one of the leads are red & blue and in the other lead black &
> yellow. (No wire is used as screening - there's just two wires in each
> lead.)

From my years of tinkering with old stereo headphones as a teenager, I'm
going to confidently guess:

Black - Left Ground/-ve
Yellow - Left +ve

Blue - Right Ground/-ve
Red - Right +ve

Martin

== 3 of 13 ==
Date: Sat, May 14 2011 2:48 pm
From: "Artemus"

"Patrick" <invalid@invalid.com> wrote in message
news:Xns9EE57F121FAB96AD265@69.16.185.252...
> I have some vinatge headphones (Sennheiser HD424) and want to attach a new
> plug.
>
> Which color wires are the positive ones?
>
> The colors in one of the leads are red & blue and in the other lead black &
> yellow. (No wire is used as screening - there's just two wires in each
> lead.)

Wire them up to a mono source and insert a dpdt switch so you can
easily and quickly reverse the phase of one earpiece. Insert a PVC
T coupling between the earpieces. Compare the sound levels coming
from the bottom of the T while flipping the switch. Loudest is in phase.
Art

== 4 of 13 ==
Date: Sat, May 14 2011 3:01 pm
From: Jamie

Artemus wrote:

> "Patrick" <invalid@invalid.com> wrote in message
> news:Xns9EE57F121FAB96AD265@69.16.185.252...
>
>>I have some vinatge headphones (Sennheiser HD424) and want to attach a new
>>plug.
>>
>>Which color wires are the positive ones?
>>
>>The colors in one of the leads are red & blue and in the other lead black &
>>yellow. (No wire is used as screening - there's just two wires in each
>>lead.)
>
>
> Wire them up to a mono source and insert a dpdt switch so you can
> easily and quickly reverse the phase of one earpiece. Insert a PVC
> T coupling between the earpieces. Compare the sound levels coming
> from the bottom of the T while flipping the switch. Loudest is in phase.
> Art
>
>
But!, Are the ears in phase? :~j

Jamie

== 5 of 13 ==
Date: Sat, May 14 2011 5:31 pm
From: "Phil Allison"

"Tim Wescott"

> "If the click seems to come from right inside your head - game over".
>
> What more do you need? Phil's given you a test to see if the phasing is
> correct, can you not figure it out, or what to do if the click seems to
> come from your right or your left?

** If both ear phones work but are wired out of phase, the AA cell click
test produces a sound that seems to be originating outside the head on both
sides. Mono speech or music sounds much the same.

The effect is far MORE pronounced than with typical stereo speakers in a
room.

The OP demonstrates his a monumental ignorance of headphones, hi-fi sound,
usenet etiquette and common sense.

.... Phil

== 6 of 13 ==
Date: Sat, May 14 2011 5:34 pm
From: "Phil Allison"

"Meat Plow"

** This trolling asshole is a narcissistic psychopath.

He knows nothing and understands even less.

I want the lunatic jerk kicked right off usenet.

Who will help me ?

.... Phil

== 7 of 13 ==
Date: Sat, May 14 2011 5:47 pm
From: "Phil Allison"

"David Looser"
Some damn idiot wrote:
>
>> It's been instructive to see how many people misunderstood what the
>> original question was trying to solve and they gave obviously useless, if
>> not misleading, advice. It's never been the same since Eternal
>> September.
>
> Actually that's untrue, nobody misunderstood the question or gave useless
> or misleading advice. And Phil is quite right, the effect of having the
> headphones out of phase with each other is not at all subtle, it is at
> least as obvious as it would be with speakers. Just because there is no
> phase cancellation in the air doesn't mean that the brain is not
> immediately aware of the phase difference heard in the two ears.

** I have come across folk with their hi-fi speakers wired out of phase and
gone un-noticed for months or years. Room acoustics and listening position
being critical to observing the fact. However, stereo headphones wired out
of phase is just the weirdest sound and not tolerated by many for long.

Headphone listening is nothing like listening to stereo speakers or natural
sounds in the environment - the outer ears are no longer involved and moving
one's head has no effect on the sound heard. The stereo effect becomes
extreme and the "sound stage" appears to be inside one's head extending left
and right as well. Plus the who damn thing moves about with your head
movements.

.... Phil

== 8 of 13 ==
Date: Sat, May 14 2011 6:26 pm
From: "Arfa Daily"

"David Looser" <david.looser@btinternet.com> wrote in message
news:937k8jFp2mU1@mid.individual.net...
> "Patrick" <invalid@invalid.com> wrote in message
> news:Xns9EE58D9D9D2126AD265@69.16.185.252...
>> On 13:07 14 May 2011, Dave Plowman (News) wrote:
>>
>>> In article <Xns9EE57F121FAB96AD265@69.16.185.252>,
>>> Patrick <invalid@invalid.com> wrote:
>>>> I have some vinatge headphones (Sennheiser HD424) and want to attach
>>>> a new plug.
>>>
>>>> Which color wires are the positive ones?
>>>
>>>> The colors in one of the leads are red & blue and in the other lead
>>>> black & yellow. (No wire is used as screening - there's just two
>>>> wires in each lead.)
>>>
>>> Black and blue are the commons. Not that it would make any difference
>>> if you commoned red and yellow.
>>>
>>> You can check for sure by unplugging the leads from each actual
>>> earpiece (red and blue plugs), but be careful to pull on the actual
>>> plug only. The pins are of slightly different sizes.
>>>
>>> Hope you have a source of the muffs for these - they crumble to dust
>>> quite quickly.
>>
>> You must know the headphones well because I had long forgotten the leads
>> plugged into the earpieces. I didn't realize the mini plugs were keyed
>> to
>> go in only one way around. With that info I could have continuity tested
>> the colored leads to each of the larger pins on the plugs but you saved
>> me
>> doing that becauase you have given me the color coding too. Thank you.
>>
>> You're right about the muffs crumbling. I threw them out. First I'll
>> see
>> what the cans sound like now and then decide if it's worth getting new
>> muffs.
>>
>> It's been instructive to see how many people misunderstood what the
>> original question was trying to solve and they gave obviously useless, if
>> not misleading, advice. It's never been the same since Eternal
>> September.
>
> Actually that's untrue, nobody misunderstood the question or gave useless
> or misleading advice. And Phil is quite right, the effect of having the
> headphones out of phase with each other is not at all subtle, it is at
> least as obvious as it would be with speakers. Just because there is no
> phase cancellation in the air doesn't mean that the brain is not
> immediately aware of the phase difference heard in the two ears.
>
> David.
>
>

+1

Arfa

== 9 of 13 ==
Date: Sat, May 14 2011 6:31 pm
From: mpm

On May 14, 7:29 am, Patrick <inva...@invalid.com> wrote:
> I have some vinatge headphones (Sennheiser HD424) and want to attach a new
> plug.
>
> Which color wires are the positive ones?
>
> The colors in one of the leads are red & blue and in the other lead black &
> yellow.  (No wire is used as screening - there's just two wires in each
> lead.)

Sounds like you got your fix.
(See Usenet really is good for something...)

Still, shoulda bought a pair of AKG K240's. :)
....unless you got a huge stash of 8-tracks laying about. !!

-mpm

== 10 of 13 ==
Date: Sat, May 14 2011 6:39 pm
From: who where

On Sat, 14 May 2011 13:55:16 +0100, Patrick <invalid@invalid.com>
wrote:

>On 13:07 14 May 2011, Dave Plowman (News) wrote:

(snip)

>> Hope you have a source of the muffs for these - they crumble to dust
>> quite quickly.

(snip)

>You're right about the muffs crumbling. I threw them out. First I'll see
>what the cans sound like now and then decide if it's worth getting new
>muffs.

I have Sennheiser HD414's from ~1980. In the last year the muffs have
gone from developing a lasting flat where they rest on a surface, to
literally crumbling.

Sennheiser's national distributor has replacements for $A9 plus
postage. I'm impressed.

== 11 of 13 ==
Date: Sat, May 14 2011 6:52 pm
From: Rich Grise

Patrick wrote:

> I have some vinatge headphones (Sennheiser HD424) and want to attach a new
> plug.
>
> Which color wires are the positive ones?
>
> The colors in one of the leads are red & blue and in the other lead black
> &
> yellow. (No wire is used as screening - there's just two wires in each
> lead.)

My first guess would be blue+ red- and black+ yellow-, but here's how to
find out. First hook them up, arbitrarily starting with what I said, or
the other way - it's a coin toss. Listen to something in mono. You'll
have to find your own mono source. (finding a mono source is left as an
exercise for the student.)

If the resulting sound comes from the middle of your head, you got
it right. If it sounds like two sources on either side of your head,
you've got the polarity wrong on one side or the other.

I'm getting this from remembering (I think) that in the old 4-wire
phone lines, green was tip and red was ring, and black was tip and yellow
was ring.
--- http://en.wikipedia.org/wiki/Tip_and_ring

Hope This Helps!
Rich

== 12 of 13 ==
Date: Sat, May 14 2011 6:57 pm
From: Rich Grise

Patrick wrote:
>
> Your lack of knowledge is made all the more lamentable by the unwarranted
> self-assurance with which you conduct yourself.
>
I believe it's time for you to go fuck yourself.

Thanks for playing!
Rich

== 13 of 13 ==
Date: Sat, May 14 2011 6:59 pm
From: "Phil Allison"

"Rich Grise"
> Patrick wrote:
>>
>> Your lack of knowledge is made all the more lamentable by the unwarranted
>> self-assurance with which you conduct yourself.
>>
> I believe it's time for you to go fuck yourself.
>

** That's more like it !!

No kid gloves when dealing with smug, arrogant pricks like Patrick.

.... Phil

==============================================================================
TOPIC: How to make antenna for a Weather Radio
http://groups.google.com/group/sci.electronics.repair/t/db4f2a9fbbc88e5a?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, May 14 2011 2:49 pm
From: "Geoffrey S. Mendelson"

JoseGomez@dotcom.com wrote:
> I got a Midland WR-100 weather radio. Because I live in a metal sided
> house, the reception is poor. On the back there is a RCA jack for
> external antenna.

> Simple and cheap are what I want.
> And redardless of that I use, can I use common TV antenna type coax,
> or do I need the stuff that was used for CB radios. (I dont recall
> the numbers used on them, but know they were not the same).

Use RG-6 (TV coax). If you have any left over, you can make a large (12")
loop out of it, anywhere along the way, so you might as well get a length
already cut with connectors attached. The connectors will be "F" connectors
for TV's etc.

Buy an F to RCA adaptor, but I doubt that it's an RCA connector. It's probably
a MOTOROLA connector that looks like a long RCA one. A Motorola connector
will fit in (and stick out) of an RCA jack, but not vice versa.

My experience with places like radio shack is that you will have to buy
an F to UHF adapter and then a UHF to Motorola. Maybe not, ask. Radio Shack
has lots of motorola plugs and adaptors, but their web site is not indexed
well and I don't feel like paging through them all.

As for the antenna, you can buy one, or make a simple ground plane or
dipole antenna. For example, a simple dipole would be two 18 inch aluminum
tubes, separated with about an inch of plastic rod. Connect each side of
the coax to one rod, and stack them vertically. You can put plastic caps
on the ends of them to prevent water getting in, but don't paint them.

You can play around with the location, orientation (horizontal or vertical)
and direction of the antenna for best results.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Occam's Razor does not apply to electronics. If something won't turn on, it's
not likely to be the power switch.

== 2 of 2 ==
Date: Sat, May 14 2011 5:05 pm
From: "Michael A. Terrell"

"Geoffrey S. Mendelson" wrote:
>
> JoseGomez@dotcom.com wrote:
> > I got a Midland WR-100 weather radio. Because I live in a metal sided
> > house, the reception is poor. On the back there is a RCA jack for
> > external antenna.
>
> > Simple and cheap are what I want.
> > And redardless of that I use, can I use common TV antenna type coax,
> > or do I need the stuff that was used for CB radios. (I dont recall
> > the numbers used on them, but know they were not the same).

Here is a link to the owner's manual:

http://www.midlandradio.com/Resource_/OwnerManual/122/WR-100B.pdf

> Use RG-6 (TV coax). If you have any left over, you can make a large (12")
> loop out of it, anywhere along the way, so you might as well get a length
> already cut with connectors attached. The connectors will be "F" connectors
> for TV's etc.

It is 50 ohm, not 75.

> Buy an F to RCA adaptor, but I doubt that it's an RCA connector. It's probably
> a MOTOROLA connector that looks like a long RCA one. A Motorola connector
> will fit in (and stick out) of an RCA jack, but not vice versa.

It is a RCA/Phono connector. I have the same unit. Use the right
connector if you want good reception. You can see it in the photo of
the rear panel on page 5.

> My experience with places like radio shack is that you will have to buy
> an F to UHF adapter and then a UHF to Motorola. Maybe not, ask. Radio Shack
> has lots of motorola plugs and adaptors, but their web site is not indexed
> well and I don't feel like paging through them all.

You don't need any adapters.

> As for the antenna, you can buy one, or make a simple ground plane or
> dipole antenna. For example, a simple dipole would be two 18 inch aluminum
> tubes, separated with about an inch of plastic rod. Connect each side of
> the coax to one rod, and stack them vertically. You can put plastic caps
> on the ends of them to prevent water getting in, but don't paint them.

A VHF ground plane cut for 162.475 MHz will cover the VHF frequencies
used by NOAA: 162.40, 162.425, 162.45, 162.475, 162.50, 162.525, 162.55
MHz

There is a sketch on the NOAA website showing the proper dimensions:
http://www.erh.noaa.gov/cae/images/antenna.gif

> You can play around with the location, orientation (horizontal or vertical)
> and direction of the antenna for best results.

The NOAA transmitters use vertical polarization.

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

==============================================================================
TOPIC: another puzzler
http://groups.google.com/group/sci.electronics.repair/t/b80657d8be4c22cd?hl=en
==============================================================================

== 1 of 2 ==
Date: Sat, May 14 2011 2:56 pm
From: "Bill Graham"

William Sommerwerck wrote:
>> But by not switching doors, you are ignoring the new information
>> that the prize has to be behind one of the other two doors....
>
> No, it doesn't. That's not correct.
>
>> You are sticking with
>> your original guess that had only a 1/3 chance of being right. By
>> switching doors, you are including the new information that the
>> prize has to be behind one of the other two doors, and your new
>> chance of winning is 50%.
>
> No, it doesn't. Your new chance of winning is 2/3.

No. You now know that the prize is not behind door $3, so your chance of
winning in the, "second game" is 50-50. But you had to buy yourself this
chance at the second game. You did this by switching doors.

== 2 of 2 ==
Date: Sat, May 14 2011 3:32 pm
From: "William Sommerwerck"

"Bill Graham" <weg9@comcast.net> wrote in message
news:C8GdnTxkFsgeZ1PQnZ2dnUVZ5jidnZ2d@giganews.com...
> William Sommerwerck wrote:
> >> But by not switching doors, you are ignoring the new information
> >> that the prize has to be behind one of the other two doors....
> >
> > No, it doesn't. That's not correct.
> >
> >> You are sticking with
> >> your original guess that had only a 1/3 chance of being right. By
> >> switching doors, you are including the new information that the
> >> prize has to be behind one of the other two doors, and your new
> >> chance of winning is 50%.
> >
> > No, it doesn't. Your new chance of winning is 2/3.
>
> No. You now know that the prize is not behind door $3, so your chance of
> winning in the, "second game" is 50-50. But you had to buy yourself this
> chance at the second game. You did this by switching doors.

I know it's unkind to tell people who agree with you that they're wrong,
but... you're wrong. You really need to think this through carefully.

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