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Old 5th Jan 2020, 12:42 am   #1
Chris55000
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Default Pitman's Valve Symbols?

Hi!

Can anyone tell me why Pitman used those horrible zig–zag lines on their valve symbols to represent thermionic valve grids?

There's a very good reason the British chose the dashed line for them, in as much as the original idea behind circuit symbols was to suggest, as far as possible within reasonable drawing limitations, how the component functions as well!

No one will convince me that the rectangle depicts resistance as easily as the "zigzag" does, and to quoue another example, the fuse, our old B.S. symbol of an angled line touching the opposite circumference of two open circles depicts a fuse far better than that box with a line thro' it, and the horrible German "magic–eye" symbol the i.e.c. inflicted upon us doesn't portray them anything like as well as the angled dashed line below an open rectangle that denotes a fluorescent target, placed at the top corner of the "magic eye" symbol, that BS530 originally recommended!

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Old 5th Jan 2020, 12:54 am   #2
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Default Re: Pitman's Valve Symbols?

I know: quite inappropriate. Why the zig-zags for valve grids? Could be that since those grid wires are wound round and round, the zig-zag presentation is someone's idea to try to represent that physical structure, as opposed to a representation of what actually happens inside a radio valve.
Fortunately, in industry, etc., the 'zig-zag' never persisted.

Sometimes, when I'm sketching out a circuit that uses valves, the glass envelopes are often drawn as rectangles. By the same token, a rectangle for a resistance was chosen simply to make life easier for draughtsmen.

Al.
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Old 5th Jan 2020, 4:09 am   #3
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Default Re: Pitman's Valve Symbols?

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Originally Posted by Skywave View Post

Sometimes, when I'm sketching out a circuit that uses valves, the glass envelopes are often drawn as rectangles. By the same token, a rectangle for a resistance was chosen simply to make life easier for draughtsmen.

Al.
I still draw resistors as zig-zags, I find it easier. Naturally a 1M gets a zig or two more than a 10 Ohm.
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Old 5th Jan 2020, 8:26 am   #4
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Default Re: Pitman's Valve Symbols?

I have been drawing a zig-zag for a resistor for over 45 years and I am not changing now. I can read a circuit with rectangles for resistors without problems though. And a transformer winding or inductor is a chain of loops, not a thick bar as the Germans like to show it.

I also learnt that a 'square wave' wiggly line (as opposed to the 'triangular wave' used for resistors) was a wirewound resistor or heating element. I rarely use that although I have done when I need to make it clear that the component has to be wirewound.

For confusing symbols (if a little off-topic) look at the ones for logic gates. The old British symbols (all boxes, with an ampersand inside for an AND gate, etc you can find them in old Mullard databooks) are downright confusing and really slow me down when trying to understand a diagram. I first learnt the old German symbols (AND gate is the 'D' shaped thing you would expect, OR gate is the same but the input lines are carried across the symbol to the curved edge), but quicky changed to the common American ones we all use now when I started workng on (American) computers.
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Old 5th Jan 2020, 10:35 am   #5
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Default Re: Pitman's Valve Symbols?

I switched from zig-zags for resistors to boxes early in my career and still use them. It was quite a surprise when I recently started using ltspice to find zig-zags again.
Its just what you are used to I guess.

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Old 5th Jan 2020, 11:24 am   #6
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Default Re: Pitman's Valve Symbols?

Quote:
Originally Posted by TonyDuell View Post
For confusing symbols (if a little off-topic) look at the ones for logic gates. The old British symbols (all boxes, with an ampersand inside for an AND gate, etc you can find them in old Mullard databooks) are downright confusing and really slow me down when trying to understand a diagram. I first learnt the old German symbols (AND gate is the 'D' shaped thing you would expect, OR gate is the same but the input lines are carried across the symbol to the curved edge), but quicky changed to the common American ones we all use now when I started workng on (American) computers.
Even worse is the drawing of logic symbols using 'intentional' logic, where for example an AND gate might be shown as a low-active OR. It makes interpretation of the actual part a tad difficult!
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Old 6th Jan 2020, 7:29 am   #7
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Default Re: Pitman's Valve Symbols?

Hi!

I never use the "active" or "functional" symbol of a logic gate, only the traditional ANSI type – I do have those IEC 60617 contraptions in my sPlan symbol libraries but they're confusion worse confounded!

It was common drawing practice in magazines to use a lot of small closely spaced "zigzags" for resistors, particularly in the "sloping lettering" 1950s era of P.W. and P.T., altho' when P.W. changed to upright lettering in the Autumn of 1961 the number of individual "zigzags" per symbol was reduced a bit!

The "square–wave" resistor symbol was mainly an old Philips relic, the only use I see for it today is a "barretter", which I draw with a "square wave" in an envelope with a open circle or spot adjacent to denote p.t.c. characteristics.

The modern recommended IEC symbol for heater elements is a reasonable representation of what it does, so I use this plus three repeated small wavy arrows adjacent to it!

By and large, my range of circuit diagram symbols is roughly equivalent to BS 3939:1966 with modern ones (e.g. MOSFET & IGBT semiconductor devices) drawn to today's representations but with a filled in rectangle for semiconductor "bars".

Chris Williams
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Old 6th Jan 2020, 7:54 am   #8
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Default Re: Pitman's Valve Symbols?

PS!

I use 1975 as the transition date between the "zigzag" resistor and "overlapping loop" for inductors/transformers, anything made up to and including 1975 is drawn the "vintage" way, whilst anything first manufactured/released January 1976 on uses the "oblong box" and the "half–moons" – this is roughly the date BS3939:1975 came out, and UK setmakers like Decca, I.T.T., R.B.M. and Thorn/BRC started to change over to the "oblong box/half–moon".

The practice of "Television" magazine of combining "zigzag" resistors with "half–moon" coils & transformers, etc., first appeared in 1972 and a great many other mags. and setmakers followed that example!

EPE Magazine uses the "Silicon Chip" style of traditional symbols with judicious use of colour to highlight different voltage rails, specific parts of circuits, etc., but I wish the Aussies would use the open plate/filled plate symbol for electrolytics!

As to today's ghastly practice of drawing everything in "single line" representation, yuck, I hate it and refuse to use the practice!

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Old 6th Jan 2020, 10:56 am   #9
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Default Re: Pitman's Valve Symbols?

One modern symbol I really hate, often used in BVWS Bulletin articles, is a to show coils or transformer windings as a 'stack of pennies' rather than a continuous 'stretched spring' shape. To me it just smacks of laziness when using a computer to draw out the circuit.

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Old 6th Jan 2020, 11:45 am   #10
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Default Re: Pitman's Valve Symbols?

Hi Andy

I've never seen a stack of pennies, but I suspect it may also be used due to a lack of ability!

I've recently been looking at car wiring diagrams and they are completely ridiculous!


Cheers
James
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Old 6th Jan 2020, 2:02 pm   #11
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Default Re: Pitman's Valve Symbols?

Quote:
Originally Posted by jamesinnewcastl View Post
Hi Andy

I've never seen a stack of pennies, but I suspect it may also be used due to a lack of ability!

Cheers
James
Errrm, I think you'll find it certainly isn't 'laziness' nor a lack of ability.

Not sure how - if you've never seen it - you can make subjective assumptions about the ability of the person who drew the circuit.

You're about as wide of the mark as you could be James, as in Andy.

Firstly, the BVWS doesn't have a 'house style' for circuit drawing - it publishes articles as written by the author, with the draft agreed between the editor and the author prior to publishing, so variations will arise. I know of only one person who draws inductors and transformers in 'stack of pennies' style in the Bulletin. He's a multi-award winning restorer - one of the most respected in the UK, right at the top of his game. (He isn't a member of this forum incidentally). He undertakes total nut & bolt strip-downs and restorations, mostly of complex 1930s sets, far beyond the abilities of many of us. His restorations involve re-winding field coils, rebuilding mains energised speakers, cabinet restorations, creating artwork for complex dials and getting them screen printed, rebuilding coil packs and replacing band-switching.

The circuits that he draws from scratch are often from almost illegible originals or scruffy Trader Sheets. The 2019 BVWS Bulletin restoration article of a complex high end 1932 radio in which the circuit you alluded to appeared, covered 13 pages, and as well as the circuit included 30 colour pictures, and diagrams of the complex dial re-stringing arrangements. Restoration of that set involved rebuilding 13 metal box capacitors, re-stuffing the reservoir/smoothing capacitor, restoring the four-gang tuning capacitor, re-building the band-switch, stripping down and rebuilding the mains energised speaker, getting a bespoke volume control made as the original was unserviceable, Then having done all that, totally rewiring and realigning the radio.

Lazy? Lacking in ability?

I don't think so - more a role model to aspire to.

As an occasional author of more modest BVWS Bulletin articles, I've never yet included a scruffy Trader Sheet or manufacturers circuit. If I couldn't be bothered to make it look neat, I wouldn't bother to submit the article to the editor for consideration, (and for the same reason, I've never posted a hand-drawn sketch on the forum). Below in pic 1 is a clip of a scruffy Trader Sheet of a Unitra Figaro Special. The second pic is the same clip after I'd completely redrawn the circuit to include in my Bulletin article, (but retaining the Trader Sheet zig-zag valve grids). The third pic is how the Trader Sheet (incorrectly) depicted the mains transformer. The fourth pic is after I'd redrawn the transformer with the tags correctly identified and the windings shown as they are. (Sorry about the 'stack of pennies', but no - for the avoidance of doubt, I'm not the author of the 13-page 1930s restoration article - I'm much further down the 'food chain'!).

Hope that sets the record straight on what defines 'laziness and lack of ability'.

Oh, and one last pop - I don't give a hoot how resistors are drawn - I understand either symbol, but I don't like zig-zag resistors so I draw rectangles as they more accurately depict what a resistor looks like, unless it's a wire-wound resistor viewed with X-Ray specs.
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Old 6th Jan 2020, 3:51 pm   #12
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Default Re: Pitman's Valve Symbols?

Quote:
Originally Posted by David G4EBT View Post
As an occasional author of more modest BVWS Bulletin articles, I've never yet included a scruffy Trader Sheet or manufacturers circuit. If I couldn't be bothered to make it look neat, I wouldn't bother to submit the article to the editor for consideration, (and for the same reason, I've never posted a hand-drawn sketch on the forum). Below in pic 1 is a clip of a scruffy Trader Sheet of a Unitra Figaro Special. The second pic is the same clip after I'd completely redrawn the circuit to include in my Bulletin article, (but retaining the Trader Sheet zig-zag valve grids). The third pic is how the Trader Sheet (incorrectly) depicted the mains transformer. The fourth pic is after I'd redrawn the transformer with the tags correctly identified and the windings shown as they are. (Sorry about the 'stack of pennies', but no - for the avoidance of doubt, I'm not the author of the 13-page 1930s restoration article - I'm much further down the 'food chain'!).

Hope that sets the record straight on what defines 'laziness and lack of ability'.

Oh, and one last pop - I don't give a hoot how resistors are drawn - I understand either symbol, but I don't like zig-zag resistors so I draw rectangles as they more accurately depict what a resistor looks like, unless it's a wire-wound resistor viewed with X-Ray specs.
Shame about the IFT and the Osc coil cores.....

Your "auto transformer" schematic drawing doesn't look right to me, there's no mains "Neutral" end shown on the primary winding....

Lawrence.
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Old 6th Jan 2020, 4:07 pm   #13
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Default Re: Pitman's Valve Symbols?

David,
I made no comment whatsoever on the technical ability of any individual regarding his track record in restoration.

My comment was aimed specifically at the 'stack of pennies' symbol for a coil or transformer, which looks completely wrong to me.
If a circuit symbol is intended to bear some resemblance to the component it symbolises, then the 'stack of pennies' looks like a Zamboni Pile'!

I am unrepentant in disliking this symbol, but please don't add 2 and 2 to make 5!

Andy
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Old 6th Jan 2020, 4:28 pm   #14
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Default Re: Pitman's Valve Symbols?

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Not sure how - if you've never seen it - you can make subjective assumptions about the ability of the person who drew the circuit.
Quite easily David,

By using the words 'suspect' and 'may'. As indeed you use the words 'assumptions' and 'not sure'. I never made any definite statement about any individual. Also the description was enough for me to easily imagine what it looked like - and I was correct.

I know many experts in one field that can't draw for toffee. It's no shame, but it would improve communication if they could.

I also see circuit diagrams drawn with no sense that the author has considered how well they might be interpreted. Drawn as part wiring diagram and part circuit diagram.

There is one single graphical construction that increases confusion and so should be avoided if possible - a big hurrah for anyone who knows what it is.

The pennies you show are not even near conveying the electrical operation of the coils of wire - indeed they are short circuit turns! And I still suspect that it was easier for him to draw flat circles than to attempt a coil of wire.

Cheers
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Old 6th Jan 2020, 4:42 pm   #15
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Default Re: Pitman's Valve Symbols?

Quote:
Originally Posted by jamesinnewcastl View Post

There is one single graphical construction that increases confusion and so should be avoided if possible - a big hurrah for anyone who knows what it is.
Two wires (lines) crossing with nothing special about the crossing point? You don't know if they are connected or not.

I must admit I combine the 2 conventions on diagrams I draw myself. A little semicircle 'hop over' if they re not connected and a dot ('blob of solder'?) if they are. It violates the standards but it is clear what I meant.
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Old 6th Jan 2020, 4:57 pm   #16
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Default Re: Pitman's Valve Symbols?

Come come gentlemen! Surely we can all read or work out the details of a circuit diagram however it is written. Most of the variations come from the Continent but I've never had a problem reading any of them.
All the best for 2020. Regards, John.
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Old 6th Jan 2020, 5:33 pm   #17
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Default Re: Pitman's Valve Symbols?

Quote:
Originally Posted by Chris55000 View Post
Can anyone tell me why Pitman used those horrible zig–zag lines on their valve symbols to represent thermionic valve grids?
Not sure but the zig zag grid started quite early:

https://www.americanradiohistory.com...h=%22audion%22

Lawrence.
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Old 6th Jan 2020, 5:42 pm   #18
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Default Re: Pitman's Valve Symbols?

My big dislike is the American way of drawing valves on circuit-diagrams where they place the pin-out connections in numerical sequence round a circle, put the diagrammatic valve in the centre of the circle, then have a spider of lines joining the relevant electrodes to the relevant pins.

If the diagram's a bit fuzzy it can really be tricky to work out where the lines go, specially when it's a multi-element valve and several of the leads cross over in order to get to their relevant envelope-pin.
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Old 6th Jan 2020, 10:06 pm   #19
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Default Re: Pitman's Valve Symbols?

Quote:
Originally Posted by jamesinnewcastl View Post
Hi Andy

I've never seen a stack of pennies, but I suspect it may also be used due to a lack of ability!

I've recently been looking at car wiring diagrams and they are completely ridiculous!


Cheers
James
If you have problems with them try railway signalling drawings. No such thing as make or break contacts. I can't remember how a changeover is depicted .
Relays are shown as a rectangle at the end of a line, with any make contacts in it's operate path as contacts above the line and break contacts as contacts below the line.
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Old 6th Jan 2020, 10:31 pm   #20
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Default Re: Pitman's Valve Symbols?

I've just had a look at my copy of British Standard 530 "Graphical Symbols For Telecommunications" dated 1948, and found the following information:

The "square wave" style resistor symbol was for non-inductive types, defined as "non-reactive for the purpose for which it is used". The general symbol was the familiar zig-zag type.

The ziz-zag valve grid symbol could optionally be used for "a grid to which a varying potential is applied" instead of the usual dashed line.
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