Getting a 1hz signal from 50hz mains using only logic gates / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

Getting a 1hz signal from 50hz mains using only logic gates

previous 1 2 3 4 next

Move Thread

LAN_403

Download

Fri May 11 2012, 08:05AM

Registered Member #561 Joined: Sat Mar 03 2007, 02:46AM
Location: Adelaide Australia
Posts: 230

That might cut out 30 odd valves from this. I'll try to find a book on this in my Uni library. Any suggestions for what to search under?

Steve Conner

Fri May 11 2012, 08:10AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I have a couple of tube-era textbooks that describe these old tricks. I think I even saw the phantastron in there somewhere.

In particular I remember there was a recipe for making a binary counter of however many bits, out of Eccles-Jordan bistables, and a technique for making it reset at any number you wanted, eg 10 instead of 16.

I'd scan the relevant parts if the books weren't all in storage while my living room gets replastered.

But at least it shows that these things were standard practice.

Edit: "Principles and Practice of Radar" was the one with a chapter on the phantastron.

The other one was "Engineering Electronics". I forgot the author, but it was from the McGraw-Hill International Student Editions series, and the cover photo showed a vacuum tube between the jaws of a micrometer.

It also had a good chapter on designing power triode oscillators for induction heating, that might be of interest to VTTC builders.

Download

Fri May 11 2012, 08:13AM

Registered Member #561 Joined: Sat Mar 03 2007, 02:46AM
Location: Adelaide Australia
Posts: 230

Got the names of the books? I might be able to find them Australia-side

It seems rather hard to find stuff on tubes

This one?

radiotech

Fri May 11 2012, 08:04PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

The phantastron scaler goes back to the nuclear age birth, where the need for electronic counters
was quite important. Your comment about reducing the number of tubes is exactly why it
was used.

The circuit depends upon a "dynatronic" kink in the pentagrid tube which employs
a negative resistance portion of the tube. That yields an especially fast transition depending
on where in RC discharge it switches. If you look at the circuit, the capacitor size changes
by a factor of 10 in each stage.

Here is some sample waveforms:

1336766667 2463 FT138169 Phantastron Waveforms

Nicko

Sat May 12 2012, 08:27PM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

Download wrote ...

I've been thinking of building a mains synchronous clock, with a catch; using only digital logic, vacuum tubes, and nixie tubes. The biggest problem I foresee, besides the large number of tubes I will need, is turning a 50hz signal into a 1hz signal for timing, I know you can get IC that do it but I wanted to do it using tubes. Has anyone seen anything that might help? or if it's even possible?

I probably won't be able to get round to this till I've got some surplus cash, but for now I'd like to get this problem of my mind :P

Digital vacuum tubes just seems so odd to me, which i why I think it will be an interesting challenge, before anyone asks

Several people have done this already e.g.

(using trigger tubes) or

or very scary

(in German, but get Google to translate it) - there are several others, even one that just uses neon bulbs -

...

Unless you really really understand tubes, do a trigger clock. Note that Grahame's first clock using XC18s had problems working in the dark (basic photoelectric effect issues - i.e. no reliable triggering without ambient photons), so he's moving to Z700Us which have a keep-alive electrode so they work in the dark reliably. We discussed using XC24s (which allow the rings to be reset) but I've never managed to find any - I have several 100 XC18s and Z700Us waiting for my next clock...

An all-tube nixie clock is a major project, even for those of us who have spent many years working with tubes and nixies. Morris Odell, one of our members (who is also Australian) has designed a 1Hz Phantastron timebase for 50Hz mains...

There are standard academic works on nixies, valve (tube) logic and counting circuits etc. The main one is Dance, J.B. (1967), Electronic Counting Circuits, London: ILIFFE Books Ltd, LCCN 67-13048. A copy of Weston, G.F. (1968), Cold Cathode Glow Discharge Tubes, London: ILIFFE Books Ltd, LCCN 68-135075, Dewey 621.381/51, LCC TK7871.73.W44 would also be great to have.

Both of these books are pretty much unobtanium but over in neonixie-l we are creating PDFs of them as they are out of copyright. There are several other good books about trigger tubes and counting techniques (tube logic using dekatrons, trochotrons, triodes, trigger tubes, neons and others).

You might consider using dekatrons as the counters, or even trochotrons (which were specifically designed to both count and drive nixies directly).

If you are serious about this, you need to get over to the Google neonixie-l group where all the knowledgeable nixie types (many are professional engineers) hang out, include the authors of the clocks I've mentioned.

radiotech

Sun May 13 2012, 04:53PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Although the HP phantastron used tubes that may appear to be hard to get, in a pinch,
I have used common 6BE6 tubes as the pentagrid. Also 12BE6s will work too.

Imagine a clock that, if the mood strikes, gives time that may or may not be
correct.

Such were the readings on the 522b units sometimes..

Clever people know what time it is. Less clever ones need clocks.

1336928004 2463 FT138169 Hp 522b Auxillary Winter Heaters

Steve Conner

Sun May 13 2012, 06:14PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I totally agree. I'd just like to add: A man with one clock knows what time it is, a man with two clocks is never sure.

I have a cheap plastic digital watch that likes to reset itself to 12.00 now and again. My best guess is small static discharges from clothing.

Nicko

Mon May 14 2012, 05:27AM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

Steve Conner wrote ...

I totally agree. I'd just like to add: A man with one clock knows what time it is, a man with two clocks is never sure.

A man with a stopped clock knows exactly what time it is twice a day...

Download

Mon May 14 2012, 06:25AM

Registered Member #561 Joined: Sat Mar 03 2007, 02:46AM
Location: Adelaide Australia
Posts: 230

Thanks for the suggestions people, I'll look into those books and that Nixie group

Bored Chemist

Mon May 14 2012, 08:22PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Turkey9 wrote ...

I don't think that the frequency is stable enough to use as a counting source. Unless maybe you can calibrate it once and a while? Then again, the error wouldn't propagate as much as it would doing the same thing with an inaccurate 1MHz clock.

Perhaps it's a transatlantic thing, but the most accurate electric and electronic clocks in my house are the ones locked to the 50Hz mains (Ok and the one on my GPS but that's cheating).

They beat the quartz ones without any problem.
For the benefit of the terminally nerdy or insomniac, there's a website where you can check.

previous 1 2 3 4 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob