Showpiece: valves and innards on show.

[SurreyNick]

Inspired by some of the homebrew sets I've seen I'm keen to have a go at making one myself, including a clear Perspex back with the innards on show, a bit like custom car enthusiasts chrome up their engines to show them off. I know this won't be to everyone's taste but each to their own etc.

I have no problem making the case and overcoming some of the other engineering challenges, but what I'd like to know is:

1. Can I employ identical looking valves with a nice bright emission?
2. Which large valves would members recommend?
3. Is it possible to adapt an existing 6-8 valve superhet to accept different valves and still retain decent performance?

Thanks.

1. I doubt you will find any good 'bright emitter' valves that work, even the 'semi bright' (thoriated) ones are rare and don't have very good emission now (I know, trying to find a good 'un for a replica radio).

2. Some of the 30's ones are quite pretty and not too expensive, I have a dud Philips 506 on the shelf, the replacement was cheap.

3. Yes, but finding a hexode or the like in big and shiny would be hard.

[camallison]

I know this sounds like sacrilege, but I saw such a homebuilt set a couple of years back with a novel solution to what you seek. The chap had put super bright LEDs, with the requisite dc supply, carefully hidden behind each valve, mounted in such a way that they looked quite bright at their base. Not quite genuine, but maybe a little kitsch - all the same, it had the required effect. He said he had played with the voltage until he managed to acquire the right level for his taste.

Colin

The heater supply would be good for this (rectified/smoothed etc.), saves a transformer! I wonder what it would look like shining up the base of a valve, easy for an all glass one or remove the tip of the spigot on things like an octal.

[camallison]

I should have added that he had indeed used the heater supply, suitably conditioned.

Colin

[paulsherwin]

The E1148/DET20/VR135/CV6 looks quite spectacular with its twin top caps and bright visible heater. It's a VHF triode used in very large numbers in the VHF section of the wartime 19 Set, so there are still lots of them around at low prices.

They were used in all sorts of homebrew projects including superhet radios in the postwar years because surplus ones were so cheap. I have a signal generator which uses a couple.

[SurreyNick]

Originally Posted by paulsherwin

The E1148/DET20/VR135/CV6 looks quite spectacular with its twin top caps and bright visible heater.

Originally Posted by merlinmaxwell

Some of the 30's ones are quite pretty and not too expensive, I have a dud Philips 506 on the shelf, the replacement was cheap.

Yeah, these are the sort of thing and also the valves on this beautiful looking homebrew set posted by merlinmaxwell. I have no idea what these valves are though.

Nick

[Ed_Dinning]

Hi Nick, those valves are fairly common triodes fron late 20's and 30's. Still being made in the 50's. Types such as HL2, HP2, PM1LF etc, etc. Try looking up any valve data book. They often goo cheaply on e-bay.

Ed

[SurreyNick]

Thanks Ed, will do.
Nick.

[FrankB]

There is a seller on ETSY which uses valves attached to USB sticks and the light in the USB stick illuminates the valve through the base.
Pretty cool looking, but spendy.

You might be able to get by placing a surface mount LED under the tube, fed by a 2 conductor ribbon cable, with the valve plugged in on top and operating. Just depends on the socket and pin grip of the valve, and the height of the SM led

[4cx250b]

How bright is bright enough?

What about using a 6AS7 as a voltage regulator? It is a very nice looking valve, with a high transconductance.

On the downside, the heater current is rather high - but something has to make the bulb light up!

[SurreyNick]

At the moment I confess I don't know which way to go

Option 1 - Mount the valves within a clear Perspex tube and light from beneath with a coloured LED (as in the sample pic from a nixie clock) - looks pretty but isn't authentic

Option 2 - Find bright valves which look identical, and which are suitable for each stage of the receiver - Will provide authentic illumination, but is impossible with my limited knowledge to identify the series of valves

Guess I will park it for the moment and return when I have a greater knowledge

Thanks for the suggestions to date though, it has been appreciated.

Nick

That is positively awful! I wouldn't mind so much if the 'gears' geared to another. No wonder these days people haven't a clue how things work. Yesterday I had the pleasure of getting a tour of a turbine research building, it was all beautiful, proper stuff doing proper things.

[SurreyNick]

Originally Posted by merlinmaxwell

That is positively awful! I wouldn't mind so much if the 'gears' geared to another. No wonder these days people haven't a clue how things work.

You don't think it's worth the $1,500 to $2,000 price tag then!!!?
Please don't think I was suggesting I'd copy this example, I was just illustrating the illuminated from below option.
Nick

[k_yller]

-red/orange glow from heater
nice big tubes russian 6c33c

[Radio Wrangler]

If the wanted light is not going to be faked, and to come from real bright emitter valves, then I'm a bit concerned that some old bottles are going to be removed from the population available for keeping the original radios which they were designed for going.

If the light is going to be faked, then where does the illusion have to stop? Some deceased valves of the right appearance could be used. LEDs could squirt light up into them, or you could even go as far as cutting the bottoms out of them and inserting small filament bulbs before glueing things back together. Some way of replacing the getter patch with non-reactive silvering would be needed. Run the vulbs a bit cool to get the right colour temperature and you get the bonus of the faked bottles running warm to the touch.

With dead bottles on show, the illusion of a functioning radio can be completed with circuitry under the baseboard. Dare I suggest period programmes on an ipod?

David

Some way of replacing the getter patch

Just clean it off, even nearer an old non gettered bottle.

[Heatercathodeshort]

Why not just 'over clean' an old working radio chassis and mount it in a Tesco plastic box? £3.99 and you can see all the guts glowing and actually working. There are some very interesting looking radio chassis obtainable for practically nothing.
Any 'glowing bits' that are fake do not do justice to vintage radio history. John.

[SurreyNick]

John, that is partially my plan. I intend to take a decent sounding set from the late valve era and re-house it in a custom art deco style wood cabinet of my own design. Why? Because I can and I like art deco.

I plan to affix a clear Perspex back panel to the cabinet so friends can see the innards and the valves in operation. The metal chassis will be custom built and highly polished, all other metal components likewise. The valves I simply wanted to swop for brighter emitters if necessary and if possible. Secondary illumination using LEDs is an option someone suggested and yes I could do it, but it's not my first choice.

Nick

[David G4EBT]

My younger son (not so young - 46) has a 'Little Bear' Chinese valve amplifier and pre-amp which both have all the 'workings' showing through a Perspex top, in both of which the valves at lit from below by blue LEDs. There are those who will instantly recoil at the sight of such offerings from the Orient as abhorrent cheap tat. Some will argue that 'form must follow function' and that anything which doesn't have a function (blue LEDs) should be denigrated as 'style over substance'. It isn't a view that I share and actually, these little amps look quite nice emitting their UV glow, but look a bit lifeless without it.

(The amps come 'flat packed' and have to be assembled).

The only problem my son had was due to intermittent connections which turned out to be flexing of the input/output sockets, attached directly to the PCB. I cured that by making some little polished brass end plates to hold the phono sockets firm. The first pic is before I added the brass end plates, the second is with the pre-amp switched on and lit up, the third pic shows the end plates I fitted.

Anyone who thinks that these Perspex and purple creations are naffolla is entitled to their view - it isn't a view I share. Don't like 'em? Don't by 'em!

Same goes for Nick's home-brew radio - if you don't like the idea of an art deco cabinet, exposed components on a polished metal chassis with illuminated valves, don't build one!

Both the pre-amp and main amp (of which I don't have pics), give a good account of themselves and have been in constant use since March.

When it comes to personal preferences, each of us will differ in our likes and dislikes.

Not everyone will like the unique amplifier (one of a pair) and speakers on display in the V&A, shown below, but I do.

I look forward very much to seeing Nicks home-brew radio when it's completed!