Nice little 3-valve vintage designs

[David G4EBT]

Just came across a website with a facsimile of a Bernard's Book featuring several simple 3-valve circuits, one of which is a superhet, with full constructional details. Some used Wearite coils - others, wind your own, with instructions given, which could be used for other circuits such as the reflex RX under discussion in another thread.

Worth a squint:

http://www.***********/doc/26612658/3-Valve-Receivers

Hope it's of interest to someone.

David

[AlanBeckett]

Interesting, but you appear to need a Facebook account
No thanks.
Alan

[G8HQP Dave]

As I understand it, Scribd is supposed to be a site for self-publication i.e. books which have too limited an audience for a normal publisher to be interested. It also gets used for copyright infringement. I had to get my publisher to ask Scribd to remove a copy of a book I edited, which had been uploaded by someone who happened to buy the book. Scribd were fine about it, it is their users who are dishonest. This same person had uploaded a number of other books.

So unless the Bernards book was uploaded by themselves, or is out of copyright, then this is a bootleg copy. Sorry to sound picky, but the labourer is worthy of his hire!

[David G4EBT]

I hadn't appreciated that.

I got to it from a Vintage radio site - I don't have a facebook account, and I'm clueless about Scribd. I just saw the book, and had no problems scrolling down the pages. I'm not sure what the copyright status is, but there is a whole raft of stuff on the net for which someone must still hold the copyright - Radio Constructor mags are archived on several sites for example.

Much of it finds its way onto the forum.

And in the case of old Practical Wireless circuits, often referred to on the forum, Practical Wireless Publishing - unlike Radio Constructor - is still very much in business, and in fact seems to draw heavily on material from its archives of yesteryear.

I wouldn't want to second guess Rob Mannion's opinion, but it wouldn't surprise me if he was quite relaxed about this as it keeps PW in the limelight.

Questions of copyright never easy matter, but in many cases - the 3-valve radios I cited, the book is long since out of print, just as are circuits and manuals for vintage radios and test gear, and as often as not, the firm that originally produced them have long since disappeared.

If someone is re-producing or copying them wholesale on a commercial basis, that's a different order of magnitude from hobbyists sharing information with no financial gain involved, and no deprivation of income from the original copyright holder.

Or so it seems to me!

The little booklet concerned, was first printed in 1952, and last reprinted in 1960 - 50 years ago Price, 1s6d). From the poor dog-eared state of the book, it looks like it's been kicking around in someone attic for most of that time

(I've just tried to link again - it opened up right away).

David

[AlanBeckett]

I've tried another few times, and in various ways, but it still wants me to join Facebook. There is a hint on there that you can be an existing Scribd subscriber, which of course I'm not. Perhaps the methodology has changed recently.
If it is in the Public Domain could someone Post it?
Alan

[rmslt56]

It took a little while to download,but all the circuits are ther to view.
I do not have facebook.
regards Doug

[Herald1360]

I looked and you can see the book on the site, but when you go for a pdf download it asks for Facebook details, which I'm not inclined to share.....

[David G4EBT]

Thanks for reading my post, and for your comments guys.

I've been away from home in London for a few days - on our way back, presently having breakfast at M1 Service Area, Donington, using my laptop and their free wi-fi access. Hence, I don't know whether or not I'll be able to print the document - not being a Facebook member. I'll give it a spin when I get home later.

However, I accessed the site in 3 secs, told my laptop to print, and it sent a print instruction to the printer, but of course it can't print from here, but it does look as though it would if in range of the printer.

I thought it was an interesting little circuit, with a clear and neat constructional layout.

Haven't had a soldering iron in my hands for a week or more, so I'm getting withdrawal symptoms

David

[David G4EBT]

Got back home earlier this evening and found that as others have said, when you ask it to print, it invites you to join Facebook or scribd. Dreeam on pal - no chance!

So I got the booklet up on the screen, right clicked on each of the eleven pages of interest (namely pages 14 - 24, which cover the 'push-pull' three valver, and the 'all-wave' three valve superhet), and saved the pages in MS Word. I had to re-size them by pulling in the corners to fit onto an A4 page, but printed them off fine and saved them.

(The 'push-pull' three valver uses three 6SN7GTs - twin triodes, (so in effect, rather like using six valves) and gives coil winding info to wind your own coil, which could be of interest in other homebrew applications that call for coils such as Denco, Wearite etc.

(The other two circuits in the book didn't interest me - a battey valve receiver and gram amp).

Hope that helps.

David

[AlanBeckett]

Thank you David, PM sent.
Al;an

[AlanBeckett]

David sent me the scans, and splendid they are
Thanks again.
One of these days .....
Alan

[David G4EBT]

Interesting little booklet - I didn't bother copying the first two articles, namely, an 'RF' gram amplifier, and a battery radio. The battery radio design used pre-war valves, with 2Volt heaters and bases that are long since obsolete - one a 5-pin, the other 7-pin.

The 'RF' gram amp is interesting from a technical standpoint. The article states:

The record player needs no direct connection to the radio receiver - it can be placed anywhere in the room which is convenient. It doesn't matter whether the receiver has pick up terminals as the signals are picked up in the same way as a normal broadcast programme. In reality, it is a low power transmitter for which no licence is required as it's radiation can be calculated in a few feet. The aerial length needs to be calculated by experiment and can be laid under the carpet.

Obviously written in pre-RA/Ofcom days, (1950) but I didn't know that there was ever a time when it was legal to use unlicensed (ans unlicensable) low power transmitters on broadcast frequencies.

Safety?

A neon is fitted as a warning that when it glows, the chassis and gram motor will be live at mains poptential, so no attempt should be made to use it in that condition. The mains connection must be reversed.

That's it then - safe as houses!

The booklet is an entertaining read, and with so many other half-finished projects, I'm having to restrain an irresistable urge to go scrabbling about in the loft for bits and bobs, and launching into building the three-valve 'push pull' receiver with three 6SN7GTs!

David.

[Valvewhiz1]

Hi David,
6SN7's are fetching silly money on Ebay these days, audiophiles buy them!!

Amanda

[David G4EBT]

Hi Amanda,

There are lots of these little vintage rx designs around - I've got most of the bits together to build a nice little one called the 'Discovery' which has four stages using two valves, which featured in Radio Constructor March 1970 and uses a twin triode ECC83 and a triode pentode ECL82.

It's on my 'to do list'.

With Denco coil fetching upwards of £18 on e-bay, I'm lucky I've got some, otherwise it would be a 'wind your own' job to christen my almost made Morris Gingery coil winder, built from scrap. I'm a war baby remember - brought up on make do and mend, not paying daft e-bay prices for anything.

So that's it then - if the audiophools who pay £300 for a mains lead and a kings ransom for oxygen free speaker leads are into them, I'll butt out and find some other twin triode that will do just as well. The 12AU7 is similar, but not identical, in electrical characteristics to the 6SN7s. Do audiophools drool over those too?

I've just had a quick look on t'internet and spent an amusing few minutes reading a comparative report on the perceived audio quality of various makes of 6SN7s as though they're connoisseurs comparing fine wines. I wonder if they'd come up with the same results in blind testing, where they didn't know which make they were listening to?

Nuff said - this is the homebrew section.

David

[neon indicator]

But all copper wire is oxygen free and always has been. Copper with oxygen in it is brittle.

Would it spoil the design to use non-denco coils? say miniature AM pocket radio ferrite rod and aerial coil. Should be tunable to 450kHz with a 330pf capacitor approx.