Narrow-Bandwidth Television Association

There's an interesting article in the current edition of Practical Wireless.

It's a mechanical replacement for a Magic Eye using a pair of green LEDs rotating about a central axis.

The whole contained in a small cylindrical tube.

Regards,

Graham

Sounds like a retrograde step to me from what you've said. Assuming you're referring to the likes of an EM84/87 etc (which had no moving parts) I can't see much reason for this except it requires lower voltages and no heater power...I wonder why it was developed? But novel I'll agree.

We don't get PW out here, in fact very few UK publications beyond newspapers which are delivered electronically anyway.

Steve A.

Was that anything like this one?:

http://www.hpfriedrichs.com/rr-magiceye.htm

You'll note that AC7ZL is a member here.

Gary, interesting...but is it that hard to find these tubes these days?...at a reasonable price? I picked up a clutch of NOS unused EM84s in the UK not that long ago for about a fiver each...far less in todays money than say in 1964. When you factor in inflation that's actually quite a bargain...however, I will concede that will not continue forever.

Steve A.

Steve Anderson wrote:Gary, interesting...but is it that hard to find these tubes these days?

Indeed it is - at least in Australia where everything is hard to get...

Steve Anderson wrote:...at a reasonable price?
Steve A.

*especially* at a reasonable price...


and before you mention buying online... think shipping... which seems to be the biggest price gouge of all in Oz...

What me cynical?

But in any case it is not a matter of availability - every one knows that a mechanical version of anything is a thousand times better than a glass bulb version - unless of course you have been indoctrinated by RCA...

Gary,

It's the same guy.

I seem to remember a posting/reference from/to him on this forum a while ago.

(Edit). Ah...Just read your comment about him being a member here.


Cheers,

Graham

Sorry Gary, It was Philips and Mullard I was impaled upon...notice I used EM84 (not 6FG6) and EM87 (6HU6)...and you think it's hard to get stuff in Oz, try it here! If it were not for my occasional trips to the UK I would be totally out of vacuum-state devices...and I'm not going to Hong Kong and paying their prices for cheap second-rate copies!

I totally agree with you on 'shipping' costs...what a farce!

Steve A.

Ah but it was RCA who started all the nonsense when we had a perfectly adequate mechanical system in place...

Actually I would probably put up with the HK quality if they offered free shipping which they often do for many other things.

Although I should have already said that I have never quite understood the point of "Magic Eyes"...

Yes, that may be true, but moves were afoot in the mid-late 30s whereby JLB must have realized the threat to his mechanical system, as wonderful as it may have been, were on the horizon. Witness his joining the CRT fraternity here....

I do not detract from what your drift is, but this man obviously recognized the threat of non-moving parts one way or another...

Do we camp out in the purely mechanical environ, or do put one foot each into either camp? He made a wise choice, investigating both, the rest is, as it is said, is history, politics, vested interests, and not the least, money.

As for myself I like tubes 'cos they are tubes, whether CRTs, small triodes or whatever...

Steve A.

Oh but Steve, JLB ventured into many things, inflatable soles, glass razors, jam, many of which, like CRTs, ended up as a dead end...

But mechanical displays live on and on... and get better and better...

I myself don't like valves (tubes, crts, whatever) because:

a) I can't make one

b) they are obsolete, collectors items, and ridiculously expensive.

d) They are adored by audiophiles who don't understand diddly-squat about audio.

c) I had zillions of them in the late 60s and, like my Marvel comic collection, grew out of them, and threw them away long before I appreciated their (somewhat dubious) future value

EDIT: hmmm, I suppose this is a kind of tube isn't it?

Yep, in varying degrees I agree...your points...

a) "I can't make one." Neither can I make a BC107, a 741 or an Intel P4.

b) "They are obsolete, collectors items, and ridiculously expensive." No different to anything that has been out of production for a while, say a Jaguar XK140 or a Piper Cub.

c) "They are adored by audiophiles who don't understand diddly-squat about audio." Now here I totally agree with you. The obscene sums of cash that changes hands for a 10W per channel amplifier...when two 2 quid TDA4040's can beat the pants off it...it's their power-bill too. If they knew just how the signals are handled in the studio, in production, editing, mix-down and all the rest they'd be a tad dismayed.

I too had loads of them in the late 60s, but with a move back to Old Blighty I had to jettison them all. I like tubes 'cos they're a link back to the past, the same could be said of NBTV which is the reason most of us are here, no? The system could (has been) improved to a point where we're as near as dammit at the limit of its potential whilst still retaining its simplicity.

Steve A.

Steve, I am sure you realise that I am being factitious regarding the use of valves (I prefer that term when referring to diodes, triodes, pentodes, etc. because that's what I grew up with). I in fact love them and encourage their use. I certainly would be using them if I had access to them (at a reasonable price). After all Baird's mechanical systems were not really mechanical, more of a hybrid. His systems would not have worked without them.

In fact transistors and ipso facto, the rest, are actually easier to build than valves (tubes) and do come into the sphere of "homebrew". Obviously a P4 is getting a bit much but a CPU built of homebrew transistors is certainly possible (even if it would make Albert's LED matrix seem a doddle).

AC7ZL's book

Instruments Of Amplification

Fun With Homemade Tubes, Transistors, And More

Is a good example of what can be done - that and The Voice of the Crystal are good reads - and I shall certainly be obtaining a copy of Marvelous Magnetic Machines when he releases it.

Note that he shows how to make valves (tubes) too, disappointingly all of those experiments require a fairly expensive vacuum pump.

However I am more serious with CRTs (which I know you love) and it is really those that I come at for various reasons not least, I can't make one.

No different to anything that has been out of production for a while, say a Jaguar XK140 or a Piper Cub.

Er, yes that was my point all right... Next time I swing by your place I'd like a look in the garage please...

Yes Gary, I do realize your antagonism....and it's all taken as tongue-in-cheek.

Sure, there's no way you can 'knock-up' a chip at wafer level at home, even if it were a humble BC107. But it is possible to replicate a simple processor using simple gates or even discrete transistors, quite a few have done it.

But why? Why would someone spend untold time and money making something that is obsolete? Even if a facsimile of the original. If it were a commission from a museum like Chris Long's mechanical television apparatus in Melbourne...that makes sense.

Here's a guy who has replicated the Apollo Guidance Computer using mainly TTL (or HC) variety gates...why did he do it? 'Cos he wanted to...

http://klabs.org/history/build_agc/

The whole thing could be replaced by a single Atmel or PIC processor these days.

Why in the UK is there a bunch of people wanting to resume in some manner or another the obsolete British monochrome 405-line standard? 'Cos they want to...and that brings us full-circle. We do this with a common aim yet different manners of doing it. I certainly don't decry mechanical methods...it's just I'm no 'kin good at it. Whereas for me a CRT is so simple...one might say no challenge therefore why do I bother? I dunno, 'cos I want to.

My garage is free for all to rummage through...if you can find it...in fact I don't even have one!

Steve A.

Oh no! not antagonism - just another point of view - tongue-in-cheek yes. I will always jack up a bit (in fun) if I hear a derogatory word against mechanical... whatever really.

But in truth the attraction to me is that, at least for NBTV, you can actually get a picture from something you have made almost entirely yourself. Maybe there's a bit of prepper in me but I have always preferred doing everything myself.

Re the garage, if you haven't got one where DO you keep the Jag and the 'plane?