HP ET-1964 Variable AC Supply

[Cubdriver]

I saw a few of these over the years on the Bay of Evil, but never bought one. Decided the next one I saw I would go for; it arrived last week. It's nothing more than a metered variac in a Clement cabinet, but is a nice unit just the same. The Variac (a Superior Electric device) is rated for up to 9 A out, but the supply itself is fused at 6.25 A, giving a good healthy safety margin. The ammeter is shunted by default to 7.5 A full scale (still need to rig up a load to check it against a digital ammeter), and the button at the bottom of the front panel opens the shunt making the meter's native 1 A full scale rating what is read.









More pics at https://pmanning.smugmug.com/Electronic ... -AC-Supply

-Pat

[Zenith]

It's a neater unit than my Lyons Regavolt, which works very well, but is just the variac in the usual round case with a huge dial/control on the top. I don't use it much, but sometimes there's no substitute. I must put it on a wooden base and add an enclosure for at least a voltmeter. The dial should give the output voltage, but it's nice to have confirmation.

[synx508]

That HP is very tidy and elegant. One of the rare opportunities to feel annoyed with British mains sockets, as you'd be lucky to fit just one on that front panel and even then you'd have to move the knob off-centre and use all sorts of bevel gears to get the driveshaft back to the middle of the variable autotransformer core.

[EC8010]

It's a neater unit than my Lyons Regavolt...

Agreed. Mine's a 10A Berco Regavolt. It's jolly heavy.

[MED6753]

That is a nice AC supply. Years ago I cobbled together this isolating supply from 2 salvaged transformers in series with a switchable output of approx 109V, 116V, and 123V. Limited to about 2 amps maximum.

Do not adjust your set, the pix is indeed a little out of focus.

[mansaxel]

This makes me want to go ahead and finish building the re-encapsulement of the Philips variable transformer I've got. It's gotten so far that it is in a 6HE Schroff Baugruppenträger (which is German for card cage) and will get a front plate from Schroff, and then have various meters and switches added, much like the -hp- unit portrayed here. I'm also playing with the idea to add a rectifier and smoothing cap to it, to get a completely insane source of up to about 325VDC Naturally using a very small fuse and safety banana jacks only.

[Zenith]

It's a neater unit than my Lyons Regavolt...

Agreed. Mine's a 10A Berco Regavolt. It's jolly heavy.

Looking at it for the first time in a year or more, mine's a 6A, (1440 kW) which should be enough for most of us. It does have a plate saying it's a Berco Regavolt. I looked into it a long time back and ISTR there are Zenith (the highest assurance of quality) variacs out there made by Lyons, so there may have been some marketing and badge engineering involved.

https://www.claudelyons.com/about-us/

Claude Lyons founded in 1918 is still going.

A couple of years back at TNMoC I asked one of the curators about keeping it running 24x7. The unreliability of valves was an objection to Flowers' design of Colossus. Flowers said valves were very reliable as long as they were turned on and left on. He had experience from working with GPO equipment. The curator said that was true but energy costs ruled it out. They ran it up slowly using a variac to avoid thermal shock and they only had to replace 10 valves a year.

I had a look round and sure enough there was a huge variac, with a notice saying it had been presented by the Claude Lyons company. I have a photo somewhere.

[Zenith]

That HP is very tidy and elegant. One of the rare opportunities to feel annoyed with British mains sockets, as you'd be lucky to fit just one on that front panel and even then you'd have to move the knob off-centre and use all sorts of bevel gears to get the driveshaft back to the middle of the variable autotransformer core.

There are several Youtube videos extolling the inventive engineering excellence of the UK mains plug. If you tread on one, pins upward, in the middle of the night when you are on the way to the bathroom, thoughts of engineering excellence are lost in a torrent of foul, filthy and indeed, profane language.

[Cubdriver]

There are several Youtube videos extolling the inventive engineering excellence of the UK mains plug. If you tread on one, pins upward, in the middle of the night when you are on the way to the bathroom, thoughts of engineering excellence are lost in a torrent of foul, filthy and indeed, profane language.

I also seem to recall reading a few times that if not properly restrained by packaging, they make excellent flails that can do a fair bit of damage to whatever they share the shipping box with, too.

LOL - As much as I like the concept of a fused mains plug, I still prefer my 'dangerous' NEMA 5-15Ps - they're less likely to damage things in shipment, and don't do their imitation of caltrops when they fall on the floor. As bad as it is finding cat barf with my bare foot while enroute to the bathroom during the night, I hope never to encounter a UK Mains Plug! I can well imagine that's a REALLY rude awakening!

-Pat

[EC8010]

My mother managed to bend one pin of a UK mains plug. I have no idea how she managed to do that without breaking the rest of the (MK Safety) plug.

[Zenith]

LOL - As much as I like the concept of a fused mains plug, I still prefer my 'dangerous' NEMA 5-15Ps - they're less likely to damage things in shipment, and don't do their imitation of caltrops when they fall on the floor. As bad as it is finding cat barf with my bare foot while enroute to the bathroom during the night, I hope never to encounter a UK Mains Plug! I can well imagine that's a REALLY rude awakening!

They are not like a caltrop. They might be pins down or on their side. Even pins upmost they don't pierce flesh. It's just that if it happens you know about it and walk funny the next day. I may have done it three times. It's not pleasant, but not dangerous.

I do like that not all plugs are moulded and we have wireable domestic plugs with cartridge fuses, from 1A to 13A. On balance, I'm not impressed with the continental Schuko plugs and sockets. We also have industrial Commando plugs and sockets rated at 120V (yellow), 240V (blue) and 440V (red). 120V for use on site through an isolating xformer. 240V has a higher current rating, from 16A to I believe 64A. 440V I've never had any dealings with,

[mansaxel]

LOL - As much as I like the concept of a fused mains plug, I still prefer my 'dangerous' NEMA 5-15Ps - they're less likely to damage things in shipment, and don't do their imitation of caltrops when they fall on the floor. As bad as it is finding cat barf with my bare foot while enroute to the bathroom during the night, I hope never to encounter a UK Mains Plug! I can well imagine that's a REALLY rude awakening!

They are not like a caltrop. They might be pins down or on their side. Even pins upmost they don't pierce flesh. It's just that if it happens you know about it and walk funny the next day. I may have done it three times. It's not pleasant, but not dangerous.

I do like that not all plugs are moulded and we have wireable domestic plugs with cartridge fuses, from 1A to 13A. On balance, I'm not impressed with the continental Schuko plugs and sockets.

I rather like them. I also like that the Schuko (IEC 7/4 as it is known in standard IEC No. 7) is unpolarised. It amplifies the alternating part of mains voltage, and puts a spotlight on the fact that both conductors can be lethal. In my head, the fused plug is a logical and necessary consequence of ring mains.

We also have industrial Commando plugs and sockets rated at 120V (yellow), 240V (blue) and 440V (red). 120V for use on site through an isolating xformer. 240V has a higher current rating, from 16A to I believe 64A. 440V I've never had any dealings with,

Calling them "Commando" is a British idea, coming from MK Connectors marketing name for their variant. They're actually connectors to IEC 60309 and a lot of vendors make them. There are a lot of variants, with colour, pin placement, insert rotation et c being used to create plugs for a lot of different voltages and current forms and frequencies; green being used for 400Hz mains for instance; violet for SELV DC, and so on.
The most common insert rotation is "6h" which means that the ground pin is aligned with the keyway in the shell; this orientation signifies the "normal" voltages and frequencies in Europe. The yellow 120V connectors differ here; they have the same 3-pole insert as the blue connectors, since they're for single phase mains, but the yellow ones are rotated so that the ground pin is in the 4 o'clock position instead.

Naturally, one has to have a few at home; this is one of the 416-6h (4 poles, ie three phases and neutral plus a 5th ground pin, 16A current, ground pin at 6 o'clock) outlets I've deployed in my workshop: