OT: Scam electronics

[William Sommerwerck]

How about a 3.5" HDTV for $41.99?
http://www.geeks.com/details.asp?invtid=ATSC-300&cat=TVS

To the ad's credit, HDTV is nowhere mentioned, nor is the display's
definition. It's a pocket TV that picks up ATSC broadcasts, and nothing
more.

 

[Dave M]

William Sommerwerck wrote:

I don't remember watching Big John & Sparky, but I sure
remember listening to the show on radio from north Alabama.
I heard it on WCKY, Cincinnati. On good days, I could pick it
up on my little rocket radio (anybody remember those?), with
the clip hooked to the bedsprings.

Oh, God, yes. $2.50 at the drugstore. Good sound -- the bandwidth was
a couple hundred kilohertz!

Yeppers, those were the cat's meow!! I used to listen to baseball games
while in school; thread the earpiece through my shirtsleeve and lean my head
against my arm all through the class. Most teachers never caught on.

OK.. here's the big question. How did those things tune in a station with
only an inductor? There was no capacitor in those gems to make a resonant
tank.
When I was in junior high school, I had already began a subscription to
Popular Electronics and Radio-Electronics magazines, and had begun reading
and studying about circuit theory. I knew that to have resonance, you
needed an inductance and a capacitance, but was forever puzzled by the
absence of a capacitor. How did they work?
--
David
dgminala at mediacombb dot net

 

[Dave Platt]

In article <NradnduQgs-GSJbQnZ2dnUVZ_oCdnZ2d@giganews.com>,
Dave M <dgminala4444@mediacombb.net> wrote:

Yeppers, those were the cat's meow!! I used to listen to baseball games
while in school; thread the earpiece through my shirtsleeve and lean my head
against my arm all through the class. Most teachers never caught on.

OK.. here's the big question. How did those things tune in a station with
only an inductor? There was no capacitor in those gems to make a resonant
tank.
When I was in junior high school, I had already began a subscription to
Popular Electronics and Radio-Electronics magazines, and had begun reading
and studying about circuit theory. I knew that to have resonance, you
needed an inductance and a capacitance, but was forever puzzled by the
absence of a capacitor. How did they work?

Two possibilities:

(1) You're mistaken, and they do contain a capacitor. The page at
http://www.crystalradio.net/misc/rocket/index.shtml shows a
schematic, which includes a fixed (100 pF) capacitor wired across
the coil terminals.

(2) Some variants may not have had a discrete capacitor, but might have
depended on parasitic capacitance (e.g. the distributed
capacitance of the coil) to create a resonant tank.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Jim Yanik]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in
news:ieg0eb$4gk$1@news.eternal-september.org:

You are probably correct. I do remember it being on radio.
But my (faulty) memory claims I watched it on a 9" Dumont.

How can anyone "watch" anything on a 9" TV?

closely.

--
Jim Yanik
jyanik
at
localnet
dot com

 

[Jim Yanik]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in
news:ieg0ht$554$1@news.eternal-september.org:

I don't remember watching Big John & Sparky, but I sure
remember listening to the show on radio from north Alabama.
I heard it on WCKY, Cincinnati. On good days, I could pick it
up on my little rocket radio (anybody remember those?), with
the clip hooked to the bedsprings.

Oh, God, yes. $2.50 at the drugstore. Good sound -- the bandwidth was a
couple hundred kilohertz!

I can remember when drugstores had lunch counters and soda fountains.
also a real wood phone booth with a rotary-dial phone.
IIRC,a call was a nickel.

--
Jim Yanik
jyanik
at
localnet
dot com

 

On Fri, 17 Dec 2010 07:43:35 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

You are probably correct. I do remember it being on radio.
But my (faulty) memory claims I watched it on a 9" Dumont.

How can anyone "watch" anything on a 9" TV?

Sit close to it.

PlainBill

 

[Michael A. Terrell]

William Sommerwerck wrote:

How about a 3.5" HDTV for $41.99?
http://www.geeks.com/details.asp?invtid=ATSC-300&cat=TVS

To the ad's credit, HDTV is nowhere mentioned, nor is the display's
definition. It's a pocket TV that picks up ATSC broadcasts, and nothing
more.

The end of the last line says its HDTV:

Enjoy watching your favorite TV shows anywhere with this Digital Prism
ATSC-300 Portable Handheld LCD Digital TV!

The ATSC-300 features a 3.5-inch color LCD display, integrated ATSC TV
tuner and an external antenna. It's ideal for travel, outdoor sporting
events or during emergencies. It also comes with an FM radio so you can
to listen to music or talk shows!

Plug in the earbud headphones into the headphone jack so you can watch
and listen without disturbing those around you. This portable TV
features a 320 cd/m2 brightness, 25 ms response time, and 55° horizontal
and 60° vertical viewing angles. The built-in stand holds the portable
TV upright for convenient viewing!

A Lithium-Polymer rechargeable battery is included as are AC and DC car
power adapters for use in your home or car power outlet. In addition,
its handheld design fits in a backpack or travel bag for complete
portability. Never miss a show or sporting event while you're away from
home with this Digital Prism ATSC-300 portable handheld HDTV!

<http://shop.retrevo.com/m/dailydeal?prodid=rd-s22;RVO-20101213-1&cmpid=Email>
is the 7" LCD TV I have, but I paid about $20 for it. It is part of my
hurricane emergency supplies. It fits in the case with my medicine
along with some LED flashlights, a SW radio nd a couple weeks worth of
batteries.


--
For the last time: I am not a mad scientist, I'm just a very ticked off
scientist!!!

 

[Dave M]

Dave Platt wrote:

In article <NradnduQgs-GSJbQnZ2dnUVZ_oCdnZ2d@giganews.com>,
Dave M <dgminala4444@mediacombb.net> wrote:

Yeppers, those were the cat's meow!! I used to listen to baseball
games while in school; thread the earpiece through my shirtsleeve
and lean my head against my arm all through the class. Most
teachers never caught on.

OK.. here's the big question. How did those things tune in a
station with only an inductor? There was no capacitor in those gems
to make a resonant tank.
When I was in junior high school, I had already began a subscription
to Popular Electronics and Radio-Electronics magazines, and had
begun reading and studying about circuit theory. I knew that to
have resonance, you needed an inductance and a capacitance, but was
forever puzzled by the absence of a capacitor. How did they work?

Two possibilities:

(1) You're mistaken, and they do contain a capacitor. The page at
http://www.crystalradio.net/misc/rocket/index.shtml shows a
schematic, which includes a fixed (100 pF) capacitor wired across
the coil terminals.

(2) Some variants may not have had a discrete capacitor, but might
have depended on parasitic capacitance (e.g. the distributed
capacitance of the coil) to create a resonant tank.

Yes, the latter explanation is the theory that I have subscribed to. The
rockets that I had didn't have a capacitor. In fact, I bought a
reproduction rocket radio from a vendor at a hamfest about 10 years ago, and
it doesn't have a capacitor either. So the only reasonable explanation has
to be the coil's own capacitance. The coil is a multilayered honeycomb
wound coil, so it has lots of distributed capacitance.

Thanks for the response,
--
David
dgminala at mediacombb dot net