UK Vintage Radio Repair and Restoration Discussion Forum

UK Vintage Radio Repair and Restoration Discussion Forum (
-   General Vintage Technology Discussions (
-   -   Drawing Trader Sheets back in the day. (

60 oldjohn 14th Sep 2020 10:16 pm

Drawing Trader Sheets back in the day.
I can not begin to imagine how these complex circuits were drawn accurately. I realise they would have had circuits from the manufactures, but TS had their own layout / style that makes them easy to follow and would need re-drawing. Would there have been a team? each doing their own set? How would they correct a mistake? Then I presume it would all have to be made in reverse for printing. Anyone know of someone involved making the TS.


Duke_Nukem 15th Sep 2020 6:07 am

Re: Drawing Trader Sheets back in the day.
Don't know what it was really like but it could be done by one person - there was just one circuit to draw per week. The consistency of the symbols might suggest a stencil would have been used, but having said that, when I started work in 1984 we still had draughtsman drawing circuits by hand and despite no stencils the circuits were very consistent. These were pencil drawn and reproduced photographically.


Cobaltblue 15th Sep 2020 9:20 am

Re: Drawing Trader Sheets back in the day.
1 Attachment(s)
I had a holiday job when I was at college working in the drawing office of a small Engineering company Liskeard Engineering 8 weeks in 1974 and 1975

Everything was drawn using rotring pens on a frosted plastic drawing sheet. Mistakes were scrapped off with a scalpel leaving the drawing medium more transparent and harder to draw on.

Circuits were drawn quite large usually 4 times oversized.

The copies were made using a Dyline copier giving the familiar blueprints it made the whole DO stink of Ammonia.

If the exposure wasn't set correctly the the errors would be plain to see as light patches on the background blue

Permanent copies were kept using a light box and a Camera.

I am not very knowledgeable about these cameras but the negatives were quite big around 4" by 5"

Obviously this is getting a bit hazy now but it was great experience :thumbsup:


Mike T

Radio Wrangler 15th Sep 2020 9:33 am

Re: Drawing Trader Sheets back in the day.
Same experience as Cobaltblue, except designers had to draw their own schematics on D-sized frosted mylar sheets. Most people used pencil for easy correction, a few od us used Rotring pens (still got my pens) Stencils weren't provided, A few people bought their own, but most used rulers with freehand for everything else.

Mechanical designers got draughting tables with protractor mounted rule sets. Electronics people taped their blank mylar to big mylar sheets with a permanent grid on them. These diagrams were used throughout development and for PCB layout, test and manufacture.

A separate department drew fresh, prettier diagrams for manuals, but these weren't used in manufacture.

THe R&D diagrams went onto microfiche aperture cards for archive.


Chris55000 16th Sep 2020 1:08 am

Re: Drawing Trader Sheets back in the day.

Yes, there was a stencil made by A. West & Partners under their "Uno" Brand for drawing Electronic Circuit Symbols, these were Refs. BB4 and BB5, I think I have a pair of these hidden away somewhere but I just can't find them at the moment!

They were designed to the slid along the top of a T–square an d the symbols drawn using the specified size of Uno Pen, then the lines added to join up all the symbols afterwards.

Easy enough for a trained draughtsman with semi–transparent drawing medium and a background grid underneath!

Amongst the publications that used these Stencil Templates were:-

a) B.B.C. Theory Papers and Engineering literature for their Valved Equipment;

b) Two books by Davie and Parr, "The Technical Writer", and "The C.R. Oscilloscope and it's Applications";

c) Solartron's Circuit Diagrams for their Valved Oscilloscopes;

d) E.R.T. Service sheets used them up until the late 1950s, then sent over to "Murphy Radio–esque" symbols which were hand–drawn after that;

e) Thorn/BRC used Uno Symbol stencils, but the heavy infilling they used on valve cathode–bars did tend to disguise them somewhat!

Of the UK technical magazines, only "Electronic Engineering" used Uno Electronic Symbol Stencils, all the other magazines had their own specially made stencil templates.

I can assure everyone that the standard lettering fonts used in those days were Uno tho!

Chris Williams

60 oldjohn 16th Sep 2020 9:00 am

Re: Drawing Trader Sheets back in the day.
I had one particular circuit I was altering, I tried drawing circuit out I just could not get it right, ended up making on Bread Board. It's not that I can not read a circuit, I can, but sometimes wonder if I have circuit drawing dyslexia. I suppose I may be better with training. Definitely not a job I could have done.


Nanozeugma 16th Sep 2020 11:18 am

Re: Drawing Trader Sheets back in the day.
More years ago than I care to remember, I used to draw circuit diagrams for myself using Rotring / Rapidograph pens with a variety of line widths and a range of coloured Indian inks. I still have the equipment somewhere, though i suspect the inks have probably dried up. The ink reservoir in the Rotring pens was a soft(ish) translucent plastic cylinder which seemed impervious to the effects of ageing - unlike the rubber bladder used to store ink the the fountain pens of the time.

mole42uk 16th Sep 2020 11:30 am

Re: Drawing Trader Sheets back in the day.
I was a circuit draughtsman in the late 1970's. Mike T has it pretty much bang-on except our Master copies were made in the same dyeline machine as the blueprints but on sensitised film.
Rötring pens & lettering stencils were standard where I worked with the addition of some in-house symbol templates made to cope with certain components which were not on the commercial stencils.
I used an A0X board with a draughting machine and we used A0 film for all circuits which were dyeline printed full-size, folded and placed in every product.

60 oldjohn 16th Sep 2020 12:05 pm

Re: Drawing Trader Sheets back in the day.
Its not the actual drawing I have trouble with, it's the visualizing. For example a bridge rectifier drawn with four vertical diodes much the same as it may appear on a PCB, Re drawn for Trader Sheets would be diodes in a diamond shape. Anything more complex and I would be struggling.


Radio Wrangler 16th Sep 2020 1:27 pm

Re: Drawing Trader Sheets back in the day.
The diamond shape is the quintessential bridge symbol, it just screams "bridge" at you. Drawn with carefully rectilinear lines and all diodes in the same orientation, it takes a moment to look as them, see how they are connected and think Bridge!

Once I spot a bridge (quickest with the diamond, of course) I then have to look at which way the diodes go. Do they point round in a circle, cathode to next anode? If so it's a diode ring mixer. Or do they form two strings pointing to a common cathode node... if so it's either a bridge rectifier or a sampling bridge.

You get a database of circuit subsections you've come across, or better yet used yourself, built up in your head. You then spot these and the whole circuit fills in the gaps and comes alive for you.

The human brain/eye is a pattern recognition engine par excelence. Build it a database, and let it fly!

That's why I like ziggy resistors, diamond bridges, diff pairs etc


saddlestone-man 17th Sep 2020 8:22 am

Re: Drawing Trader Sheets back in the day.
This thread has brought back the memory from when I worked at Plessey Edge Lane, Liverpool in the 1970s. The smell of ammonia from newly printed schematic sheets was great at clearing a blocked nose!

Am I right that the sheets had to be left in the sunshine for a while to develop fully?

best regards ... Stef

Cobaltblue 17th Sep 2020 8:51 am

Re: Drawing Trader Sheets back in the day.
I don't recall leaving them out other than to dissipate the smell of Ammonia the paper had a yellow coating and needed to be kept in the dark the rolls arrived in thick black plastic covering.

The machine we used UV light to expose the paper which was in contact with the original once exposed it was developed by the ammonia the sheets were very large A0 or perhaps bigger.

This mind you is memories from 45 years ago :thumbsup:

They were then folded down to A4 size I can't remember exactly how they were folded but it left them like a pouch so they didn't unfold and stayed flat.


Mike T

Uncle Bulgaria 17th Sep 2020 9:29 am

Re: Drawing Trader Sheets back in the day.
I find drawing circuit diagrams difficult because I have to go component to component, and then the common linking wire elements end up having to jump over each other and the whole thing becomes terribly messy. I imagine there are techniques that the professionals learned to lay out things neatly, or as David says, if you have the database then there are logical ways that one will know for how the subsequent components are going to link. A transformer connected to a bridge springs to mind - I can visualise that and draw it neatly all going horizontally. I imagine seeing it for the first time and tracing it out that it would be a mess of parallel diodes and confusing links.

At architecture school in 2012 I went to Manchester to pick up a free dyeline printer and some gallons of ammonia as I liked the drawing texture I'd seen in other architects' drawings I was studying at the time. We put it in the cellar and made great scrolls of tracing paper with drawings on so as to end up with a long dyeline sheet to stand out in tutorials. The paper is UV sensitive, so leaving it in the sun is a bad idea as it will fade to nothing. The ammonia sets the exposed paper so it is more resistant to UV, but it's not a permanent medium and if in bright light will fade markedly. I still have the printer as I hope to use it in more projects. With everything now drawn on computer the textural nature of dyeline, even if printed from computer plans, is very appealing and a bit more approachable for those not well versed in reading technical drawings.

Craig Sawyers 17th Sep 2020 4:02 pm

Re: Drawing Trader Sheets back in the day.
Ah - dyeline printers, Roneo printers - great memories. Thank heavens they are technologies of yesteryear.

Long stories about my quest to banish hand drawn mechanical assemblies and dyeline from Oxford Instruments and drag them kicking and screaming into the 20th century of CAD and CNC manufacture.


Chris55000 17th Sep 2020 10:21 pm

Re: Drawing Trader Sheets back in the day.

But my drawings won't be dragged kicking and screaming into 21stCentury Chinese jigsaw–puzzle format – the best circuit drawings came out of the magazines and Thorn/BRC at Enfield and that's where my styling stops – see my Hunts CRB3 diagram for an example!

Chris Williams

Craig Sawyers 18th Sep 2020 6:57 am

Re: Drawing Trader Sheets back in the day.
Two schematic-meisters were Tektronix through to the end of the 7000-series mainframes and plugins, and Quad.


Radio Wrangler 18th Sep 2020 10:06 am

Re: Drawing Trader Sheets back in the day.
As an object lesson in how not to draw a diagram, can I draw attention to the block diagrams provided for just about every Japanese amateur radio transceiver?

They are drawn as a regular array of identical rectangular boxes. All locations in the array being populated. You have to read the text in each box to find out what it is. Then the boxes are 'wired' together by lines squeezed together in the space between the boxes. The routing seems to always take the shortest route at first, then later ones add avoiding congestion to the rules, then later, when congestion can't be avoided, it all gets messed up.

Superb example of a diagram which contains the info you want but it is camouflaged to the point of uselessness.


m0cemdave 18th Sep 2020 9:01 pm

Re: Drawing Trader Sheets back in the day.
Mmmm, Yaesu service manuals...

Radio Wrangler 18th Sep 2020 11:04 pm

Re: Drawing Trader Sheets back in the day.
Stir in a quality of reproduction which can only be described as 'poxy' and you're left wondering it that is a dotted connection of just a copier blob.


All times are GMT. The time now is 1:27 am.

Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.