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Old 8th Sep 2017, 3:42 pm   #41
thermionic
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Default Re: Vintage switched mode power supplies

Quote:
Originally Posted by ms660 View Post
Syclops...Not that early but anyone remember them
Oh yes, Thorn 9000, launched in 1975 or thereabouts I think. Another Thorn milestone. Like the 3000, the 9000 had cleverly designed power supply & line stages.

At the time, to a busy service engineer, they could be a nightmare, prompting much swearing and sweating!

But looking back I think that they were way ahead of their time. The combined chopper power supply & line output stage was a first. Great, until you had to find why it was 'tripping'.........


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Old 8th Sep 2017, 3:55 pm   #42
ms660
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Default Re: Vintage switched mode power supplies

Yes, chicken/egg and then some.

Lawrence.
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Old 8th Sep 2017, 4:04 pm   #43
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Default Re: Vintage switched mode power supplies

You can imagine a conversation of the past in some diabolical meeting...

"And we'll use a thyristor just to really fool them..."

followed by peals of demonic laughter


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Old 8th Sep 2017, 4:10 pm   #44
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Default Re: Vintage switched mode power supplies

My first encounter with SMPSU was in a Practical ( name the mag-Electronics/Wireless etc) , car CDI electronic ignition unit, in the mid 70's to get 350V DC . It was a discrete unit using 555 to do the job. But Marconi have been using similar discrete stuff using logic circuitry since roughly the same time and the PSU on the 353 is a prime example - 24v in, final anode on the transmitter = 800v DC ,with up to 50W transmitter power .
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Old 10th Sep 2017, 3:08 am   #45
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Default Re: Vintage switched mode power supplies

I recall that early efforts to analyse operation of buck and boost topologies (with their many permutations of circuit format) pointed back to early chopper drives as the first major use of simple duty-cycle control of switches to generate a controlled output from a raw input.

Chopper drives for generating very large controlled power outputs were quite an industrial revolution in allowing high current applications to become more efficient and controllable.
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Old 10th Sep 2017, 7:51 am   #46
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Default Re: Vintage switched mode power supplies

Chopper drives with pulse width modulation went back to the days of big thyratrons.

Big stationary plant could afford them while traction motors were still controlled by field reheostats in trams and trolley buses. Diesel-electric locos could use the Ward-Leonard technique with their on-board generator.

Lathes were good examples of the benefits of variable speed motors, you only had to look at the mechanical complexity they replaced with electronic complexity. Toolroom grade lathes were expensive enough to afford the complexity.

The Monarch 10EE acquired its "WiaD" chopper (AC to variable DC) in 1949 and went through many generations of chopper design until new ones came with a variable freq inverter in the 1990s.

Colossus as recreated uses a motor controlled variac to slowly bring up and regulate its heaters. I wonder if any later valve computers used chopper regulation?

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Old 10th Sep 2017, 9:44 am   #47
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Default Re: Vintage switched mode power supplies

The only time I ever had a legitimate excuse to let off a fire extinguisher was during initial tests of a largish dc PSU (about 90kW) which used a motorised VARIAC in the preregulator. Nothing to do with the VARIAC, though. A reversed electrolytic in bank of about 25 in parallel was the fuse/firestarter.

There was that "slow motion inevitability" about the incident- winding up (literally) to full power the first time, there was time to think "why's that humming noise gettiing much louder" as the rollers went up the coils, but I was still heading for the big red button when the cap let go!

A year or so later (mid '80s) we started to go switch mode though after a not very promising first full switcher, various thyristor pre regulator and converter/inverter configurations took over for a while.
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Old 21st Sep 2017, 9:52 pm   #48
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Default Re: Vintage switched mode power supplies

I worked on an Argus 500 and remember that it had very reliable switch mode power supplies operating in the high Khz range from the sound they made.

Whilst checking the dates for the introduction of the Argus 500 I found my old company Argus Delivery listed via a search engine internet document pinpointing the year to 1968.
Strange what lurkes in odd corners of the internet.
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