Mystery Power Supply by Dukes & Briggs

[Yorkie]

I bought this power supply some years ago from a car boot sale for £3.00 with no great expectation that it would work. The logo on the front 'Regulated Power Supply B' seems to suggest the outline of a power transistor - 2N0555 or whatever, so I mistakenly assumed that it would be solid state. However, when I removed the supply from its case, I discovered that it has three valves - an EL34, an EF86, and what appears to be a 150V regulator valve marked 'GD150'. The unit is solidly built to a good standard and has two transformers - one to provide 6.3V AC - the other to provide 150V fixed and regulated, (at only 7mA) and from 0 - 300V variable at up t0 60mA.

It has four fairly small metal rectifiers and on the rear of the main transformer there is a thermal trip set to trip at 400mA - far above the 60 mA that the unit is intended to provide.

None of the components (EG, electrolytics) have dates on them, and the serial number doesn't give a clue, but I guess it will have been made in the mid 60s. The manufacturer was Dukes & Briggs Engineering of Urmston, Manchester. Internet searches have drawn a blank - it would have been nice to have a circuit. One of life's little mysteries, and will remain so I guess. Quite how it found its way from Manchester to a car boot sale at Beverley Racecourse is another little mystery.

Luckily, to date, it's worked fine and often come in handy for such little tasks as powering the magic eye tester I've just made, so my £3.00 punt has paid off handsomely!

[Yorkie]

No sooner had I written that post, than I came across a circuit for it 'over the wall' at this link:


http://www.vintage-radio.net/forum/showt...hp?t=13142

[pwdrive]

Yes, classic choke input series pass jobbie, I knocked one up to power some of my receivers (using a 6080) does the job, not a lot to go wrong in the complexity stakes.

Lawrence.

[camallison]

I remember that power supply from my night school time when I did my HNC way back in the 60s. Valves were still on the curriculum and as bench supplies for "experiments" we used those. So maybe yours was originally from a local tech college David?

Colin

[pwdrive]

http://news.google.com/newspapers?nid=2507&dat=19651106&id=CmxAAAAAIBAJ&sjid=gaMMAAAAIBAJ&pg=3525,999643

Lawrence.

[camallison]

http://news.google.com/newspapers?nid=2507&dat=19651106&id=CmxAAAAAIBAJ&sjid=gaMMAAAAIBAJ&pg=3525,999643

Lawrence.

Then, in 1986, Endress & Hauser terminated the licence to manufacture and sold German-manufactured level controls through a sales office in Wythenshawe with staff recruited locally (perhaps from D&B?)

Colin

[pwdrive]

http://news.google.com/newspapers?nid=2507&dat=19651106&id=CmxAAAAAIBAJ&sjid=gaMMAAAAIBAJ&pg=3525,999643

Lawrence.

Then, in 1986, Endress & Hauser terminated the licence to manufacture and sold German-manufactured level controls through a sales office in Wythenshawe with staff recruited locally (perhaps from D&B?)

Colin

Ah... Wythenshaw, I remember it well, one of our main service departments was there, used to swim at Wythenshaw baths if we finished our TV field service calls early (don't tell the boss...)

Lawrence.

[Yorkie]

Thanks for your input guys.

It could well have been used at a college because on the same table was a little student scope (valves) which I also bought for £3.00 because it was a dinky little thing, the name of which escapes me, but will be known to other forum members no doubt (Serviscope?). Only about a 6" cube. I bought it on impulse - I didn't need it, and I got rid of it in one of my periodic clear-outs.

The circuit of the PSU at the link I quoted is a big help as it makes it obvious what the four metal rectifiers do - two half wave ones in each bridge, so should they fail at any time, solid state bridges could replace them. I didn't study the physical layout too closely when I took the pics, otherwise I'd have realised that that one of the 'transformers' is actually a choke.

I guess my 'best buy' at a stall was a brand new Weller TC1 solder station for a tenner about 15 years ago. The chap had six - maybe I should have bought all of them! (His firm had closed).