From Newsgroup: rec.woodworking


why am I seeing this today?


Alexander Thesoso <alexander_thesoso@hotmail.com> posted:

When I said:
"In all seriousness, what a wonderfully goofy idea!!!
Whoever thought this up deserves an award for creativity."
I was expressing awe that our society can produce such a product.
I don't want to pick a fight about the explosive subject of combining
the words 'rational' and 'vinyl' in a discussion. (I still have a good working vinyl system.)
Thinking about how this thing works...
The left and right wheels are separately servoed.
A common speed input goes to each servo.
A tracking signal, derived from the stylus displacement from center, is
a differential input to the servos. This centers the stylus and makes
the thing go in a circle (ok, spiral).
The difference in rotation of the wheels is used to derive a radius
measure, which is used to generate the speed input signal, to make the
speed compensate for the different linear velocity at different radii.
(Or money could be spent on a gyro to get rotation rate.)
All this is done in a fairly-low-volume toy at an amazingly low price.

On 4/22/2011 4:16 AM, George W Frost wrote:

"DoN. Nichols"<BPdnicholsBP@d-and-d.com> wrote in message news:slrnir1vvc.ku0.BPdnicholsBP@Katana.d-and-d.com...

On 2011-04-21, Alexander Thesoso<alexander_thesoso@hotmail.com> wrote: >>> On 4/21/2011 12:22 PM, Rob H. wrote:

"Lloyd E. Sponenburgh"<lloydspinsidemindspring.com> wrote in message >>>> news:Xns9ECE7ADBE542Alloydspmindspringcom@216.168.3.70...

[ ... ]

It's a record player. It "drives" around the record, following the >>>>> groove.

Correct!

http://www.x-tremegeek.com/soundwagon-vw-minibus-portable-record-player.html

In all seriousness, what a wonderfully goofy idea!!!
Whoever thought this up deserves an award for creativity.

Or -- to be jailed for cruelty to records. I can't imagine any
way that this would track properly without exerting enough force on the
stylus so it would rapidly shorten the life of the recording.

And -- what RPM is it set to? It is bound to be wrong
everywhere except at one radius.

RPM or MPH ??

And if you put it on backwards, it would play the record
backwards, as in some of the old stories about nasty trick built into
some rock recordings. :-)

Enjoy,
DoN.

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