[QuadList] Mains frequencies, control, similarities to genlocking
David C. Crosthwait
david at dcvideo.com
Sun Apr 11 09:21:09 CDT 2010
Steve,
Thanks for the explanation. The scene of nuclear sub sailors piling
into the Hi Fi store must have been something to see.
The Sansui story rings a bell. In the late 60's as a teenager, I came
across a GI who had just returned from Vietnam. This was in Ft. Worth
Texas. He had with him a Sansui 3000 receiver, a model I have never
found since. My cousin bought it and is still using it to this day. I
guess he was lucky as I can't recall any transformer horror stores,
etc. But I always wondered why I've never seen (through casual
searching) another one like it. Since then, I have seen other
references to Sansui equipment "for sale" i.e. eBay that were bought
by servicemen overseas.
David
www.dcvideo.com
Quoting Steve Spears <stevespears at kel.com>:
> Brian...
>
> It's interesting that you should mention that, because that's
> precisely an event that Akai in japan went through (by their own
> rotten doing) from about 1963 to 1968.
>
> They sold the Akai tape recorders in the U.S. under the Roberts
> label. In 63, while still in high school I worked at Westlake TV and
> HiFi in Daly City, just outside of San Francisco. A Navy nuclear
> sub docked and a whole bunch of sailors came to the store looking
> for warranty repair on their Akai tape recorders, all with burnt
> out power transformers. The same problem we were seeing with a slew
> of Roberts decks. Akai had tried to cut some corners on the
> assembly line with some of the 50hz power transformers and it
> backfired. Or maby I should say..."backsmoked".
>
> When I was stationed in Japan from 1965 to 1967, I was able to learn
> all about the real background of Akai, from the japanese people
> themselves, and it was'nt pretty. Akai was just a brand that was
> really born for the "Kanazawa" HiFi circuit, a contract company that
> ran the electronics department up and down the country in all the
> U.S. base exchanges. Two company's in particular stood out, that
> mainstream Japanese consumers would'nt touch with a ten foot pole.
> Akai, and Sansui. Purely junk, and peddled to the U.S. military as
> being really high class.
>
> I opened up a Sansui 1000 receiver one time, the one that sold more
> than any of their other products. The first thing that set off some
> red flags...the auxiliary AC receptacles on the back, were wired
> with #22 solid hookup wire. The same stuff I was using on my
> American Flyer trains as a kid. Fine for the amplifier circuitry,
> but not quite AC accessory outlet proper.
>
> A friend of mine at Ashiya, that ran the local TV and Stereo and
> Appliance store, got me a copy of the Sansui annual report, a nice
> little color booklet that showed all of it's divisions and products.
> Their primary productline and business, was AC power distribution
> equipment for the public utilities. Sort of like GE or Westinghouse
> or Allis-Chalmers here in the U.S. Transformers, oil circuit
> breakers and the like. In the very back of the annual report, 1 page
> with pictures and description saying basically "and we're also in
> the consumer hi-fi business with a few products". Like Akai. Sansui
> audio gear was very seldom bought by the Japanese people because
> they knew better.
>
> All the best to all of you,
>
> Steve Spears
> Orrs Island, Maine
> www.kel.com
> ----- Original Message -----
> From: Gideon4
> To: Quad List
> Sent: Saturday, April 10, 2010 5:13 PM
> Subject: Re: [QuadList] Mains frequencies, control,similarities to
> genlocking
>
>
> Re the 60/50Hz business, one of the Gotchas is transformer
> overheating, or to expand, A transformer designed for 60Hz has
> slightly less Iron in it than the comparable 50Hz one. If you have a
> "budget transformer" in a item of kit from a 60Hz source, they
> would often saturate on 50Hz, get hot and burn out. Been there,
> done that!
>
> Brian Summers
> -----Original Message-----
> From: quadlist-bounces at quadvideotapegroup.com
> [mailto:quadlist-bounces at quadvideotapegroup.com]On Behalf Of Ted
> Langdell
> Sent: 10 April 2010 19:22
> To: Quad List
> Subject: Re: [QuadList] Mains frequencies, control,similarities
> to genlocking
>
>
>
>
> On Apr 10, 2010, at 10:53 AM, Chuck Reti wrote:
>
>
> Not documented anywhere I've looked, but wonder if 60Hz might
> have been chosen since it correlates with 60sec/min - 60min/hr
> timekeping.
> Did make it easier to do electric clocks!
> --
> Chuck Reti
> Detroit MI
>
>
>
> Keeping time with motor-based clocks is an interesting
> situation. See the link and text below.
>
>
> The process has some elements of pre-framesync Genlock... (Think
> rubidium) and since this is Saturday, would have been something
> networks were doing with sports events from remote locations.
>
>
> Googling "Genlock Remotes" brought up a 2009 patent application
> by CISCO, the data router people in regard to Genlocking remote
> video sources:
>
> http://www.wipo.int/pctdb/en/wo.jsp?WO=2009105593&IA=US2009034598&DISPLAY=STATUS
>
>
> Genlock and framesyncs turn up in the April "CBS Retirees
> Ramblings" here:
> http://www.cbsretirees.com/blog/blogger.html
>
>
> You'll see a couple of items from Harold Deppe (Sr.,) who was in
> Maint. at CBS in NYC and is on the QuadList. We may have the only
> Father/Son pair of engineers on a video-related discussion list, for
> all I know.
>
>
> Back to power for a tad:
>
>
> The section below on Frequency and Load has me wondering whether
> it would be practical to monitor the powerline freq., with limit
> alarms to indicate that a power "event" like a brownout, load shed
> or blackout was about to happen.
>
>
> Ted
>
>
>
> http://en.wikipedia.org/wiki/Utility_frequency#Long-term_stability_and_clock_synchronization
> Long-term stability and clock synchronization
> Regulation of power system frequency for timekeeping accuracy
> was not commonplace until after 1926 and the invention of the
> electric clock driven by a synchronous motor. Network operators will
> regulate the daily average frequency so that clocks stay within a
> few seconds of correct time. In practice the nominal frequency is
> raised or lowered by a specific percentage to maintain
> synchronization. Over the course of a day, the average frequency is
> maintained at the nominal value within a few hundred parts per
> million.[17] In the synchronous grid of Continental Europe, the
> deviation between network phase time and UTC is calculated at 08:00
> each day in a control center in Switzerland, and the target
> frequency is then adjusted by up to ±0.02% from 50 Hz as needed, to
> ensure a long-term frequency average of exactly 24×3600×50 cycles
> per day is maintained.[18] In North America, whenever the error
> exceeds 10 seconds for the east, 3 seconds for Texas, or 2 seconds
> for the west, a correction of ±0.02 Hz (0.033%) is applied. Time
> error corrections start and end either on the hour or on the half
> hour.[19][20] A dynamicdemand.co.uk/grid - Real-time frequency meter
> for power generation in the United Kingdom is available online.
> Smaller power systems may not maintain frequency with the same
> degree of accuracy.
>
>
>
>
> Frequency and load
> The primary reason for accurate frequency control is to allow
> the flow of alternating current power from multiple generators
> through the network to be controlled. The trend in system frequency
> is a measure of mismatch between demand and generation, and so is a
> necessary parameter for load control in interconnected systems.
> Frequency of the system will vary as load and generation change.
> Increasing the mechanical input power to a synchronous generator
> will not greatly affect the system frequency but will produce more
> electric power from that unit. During a severe overload caused by
> tripping or failure of generators or transmission lines the power
> system frequency will decline, due to an imbalance of load versus
> generation. Loss of an interconnection, while exporting power
> (relative to system total generation) will cause system frequency to
> rise. AGC (automatic generation control) is used to maintain
> scheduled frequency and interchange power flows. Control systems in
> power plants detect changes in the network-wide frequency and adjust
> mechanical power input to generators back to their target
> frequency. This counteracting usually takes a few tens of seconds
> due to the large rotating masses involved. Temporary frequency
> changes are an unavoidable consequence of changing demand.
> Exceptional or rapidly changing mains frequency is often a sign
> that an electricity distribution network is operating near its
> capacity limits, dramatic examples of which can sometimes be
> observed shortly before major outages.
> Frequency protection relays on the power system network sense
> the decline of frequency and automatically initiate load shedding or
> tripping of interconnection lines, to preserve the operation of at
> least part of the network. Small frequency deviations (i.e.- 0.5 Hz
> on a 50 Hz or 60 Hz network) will result in automatic load shedding
> or other control actions to restore system frequency.
> Smaller power systems, not extensively interconnected with many
> generators and loads, will not maintain frequency with the same
> degree of accuracy. Where system frequency is not tightly regulated
> during heavy load periods, the system operators may allow system
> frequency to rise during periods of light load, to maintain a daily
> average frequency of acceptable accuracy.[21][22]
>
>
>
>
> Ted Langdell
> Secretary
>
>
>
>
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