The first time you saw a solid state SMPS

[CJay]

Thorn 9000 SYCLOPS psu, bloody horrible things.         

@Kjelt, never seen an ST with an external PSU, didn't realise they made them!!

Interesting model I'd never heard of that one, by then I was in France, not sure many UK TV's got exported to France in those days.
I remember working on a (Nokia IIRC) chassis with a single power/LOP transformer it was infamous for it's thick film hybrid module controlling the SMPS, Grundig also made a model (better design than the Nokia) with a single power/LOPT.

Didn't know either of the Atari ST with external power...

I'd sure count a LOPT flyback as SMPS, wouldn't count spark gaps, vacuum tubes or vibrators as solid state though.

Not many did, PAL vs SECAM...

Might the 'Nokia' have been a Salora/Luxor set, with the IPSALO PSU, that had a thick film AFAIR.

Grundig had the venerable TDA4600 and TDA4601 SMPSU controller ICs, the PSUs could be really 'delicate' though, they went bang if anything drifted out of tolerance.
 

[shakalnokturn]

You're right CJay:
Salora/Luxor/Hitachi IPSALO stuff, the thick film (LF0059  I still have one hanging around) bears a Nokia logo on the back, that may be why I'm confused, I wouldn't swear I've seen it in a Nokia banded TV...

[chris_leyson]

Not sure if inverters count as SMPS, the HT inverter in a PYE Cambridge that was used to power the output tubes 2 x QQV03-10.

[spec]

In the 1960s we didn't have the cash to eat regularly and everything was expensive. Our TV was an eleven-year-old, 14" goldfish bowl Bush, in a beautiful veneered cabinet, the car was an ancient wreck, and all electronic parts were pulled from scrap equipment, mainly TVs.

Unlike, in 2018, car radios were only for the well-off, and in any case, they were valve with noisy, unreliable, mechanical inverters, or low voltage valves with no inverter and possibly a solid state output stage. The latest all-transistor car radios were way beyond the reach of the poor and, anyway, in those days, they didn't seem to have the performance of the traditional valve car radios, RF performance being all important to get Radio Luxembourg and AFN.

There was though, a few valve car radios with solid state inverters in place of the mechanical inverters and, as these inverters were dreadfully unreliable, there was a load of these faulty radios available for a song. Thus, my first carnal knowledge of solid-state switching PSUs was with car radio inverters around 1966.

IIRC, there were two types of solid-state inverter: single transistor fly-back, and two transistor Royer. After having no success with the single transistor type, I focused on the two transistor type, which were much more reliable and predictable.

To short a long story, after about a year of experiments and a mountain of  blown OC28 and OC36 PNP germanium power transistors, I eventually fathomed the workings of the Royer oscillator and  managed to get a set working reliably, but for some reason, after all the effort, the set never did get installed in the car.

[bd139]

I’ve actually just snagged a whole load of Mullard pot cores off eBay to try and make a Royer converter. Hope I have more luck

[spec]

I’ve actually just snagged a whole load of Mullard pot cores off eBay to try and make a Royer converter. Hope I have more luck

Royer inverters are great fun and are quite easy to do these days, providing you know their critical areas. The big thing is to avoid early core saturation and transistor overlap, where both transistors are conducting at the same time. This kills the transistors and greatly stresses the core, and was the great mystery in my early days before I got the theory of Royer inverters.

With modern chips cheaply available my advice would be to use an oscillator (555) and gate driver chip with dead time control.
You would then have a much more flexible design with a performance that would beat a Royer inverter by a mile.

Be a very good subject for a new thread on the forum. I'm sure it would attract a lot of interest and comments.

In any case, good luck with your Royer experiments and let us know how they go.

[bd139]

Thanks for the tips. Much appreciated. I’ll create another thread when I get to play with them. My intention is developing CRT bias and dual rails for a home brew scope with it ultimately but I’ll probably get bored by then

[spec]

Ha Ha Ha- my pleasure.

Following on from the car radio inverter experiments, I had a twenty-year on-going development program of designing and building scopes. The first scope used a CV138 ex military radar tube and mains transformer and valves from TVs.

But after that I moved to a lab next door to the SE Labs scope development department at work. I immediately got friendly with the engineers and they let me have a load of parts, including a four-inch round, flat face tube with high sensitivity x and y plates, complete with mumetal screen. That was the basis of my next scope which ran off 12V and used a Royer inverter for the EHT, HT, tube heater, +-100V and +-15V supply lines.

Then they let me have a 5" x 4.5" flat face graticule tube, which was the basis of the next scope. But I never finished that.

Then they let me have a practically complete pre production SM111 scope, less the cosmetic bits, like case covers and engraved front panel.

None of my home-brew scopes were totally complete, so finally I bought a faulty Gould OS100A for £5, and then a succession of other scopes. When we moved house a lot of my stuff went down the tip. Now I just have a Tek 2235A.

[bd139]

Excellent stuff. I've got a VCR139A tube sitting here waiting. It'll be a very basic scope but hopefully enough scope to tick the bucket list box

My father had an SE Labs scope for a couple of years. He really loved that but it was a leased one so had to give it back. I'd have killed for (and probably would today) for access to parts like that.

Collecting scopes here, perhaps unfortunately. Got 4 Tektronix and 2 Telequipment units floating around.

[BrianHG]

My Amiga 1000 power supply.  BTW, I just loved the quiet smooth deep sound of that true 120v AC fan with the heavy bearings instead of today's dinky 12v DC fans.  Also, the supply had very little to almost no leakage current to the mains.  Nicely filtered, or maybe a really small X cap value.

[spec]

Excellent stuff. I've got a VCR139A tube sitting here waiting. It'll be a very basic scope but hopefully enough scope to tick the bucket list box

My father had an SE Labs scope for a couple of years. He really loved that but it was a leased one so had to give it back. I'd have killed for (and probably would today) for access to parts like that.

Collecting scopes here, perhaps unfortunately. Got 4 Tektronix and 2 Telequipment units floating around.

What a great shame; six years ago I could have sent you a really nice  Xmas present as you live in the UK.

The biggest problem with a tube like the VCR139A is the low X, and to a degree, Y sensitivity. You can provide the volts, but it is a job to get much bandwidth. Modern components will help a lot though.

[spec]

I'd have killed for (and probably would today) for access to parts like that.

You know, your best bet is to get a faulty production scope. Very often the PSUs fail and render the scope uneconomical for a pro repair but, presumably your time is free, and the repair should not be too difficult.

Perhaps get in contact with one of the second-hand test equipment dealers or watch out for ads on ebay etc. Go or a basic scope though, or you may get stuck for specialist parts and difficult fault finding. One of the basic SEL scopes, for example, would be ideal.