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August 13, 2016 / consort3

TTL & Microprocessors

TTL (that is transistor – transistor logic) is 50 years old–more-or-less–in-2014-

Good article on the history of TTL

A 4bit microprocessor built in TTL

An even simpler TTL processor

A more complex TTL microprocessor

See inside the 74181 ALU

A TTL processor that does not use the 74181 ALU also interesting web-ring

Not a lot of people remember the Signetics 8200 series and the AMD 9300 series TTL

While I am on a historical bent, this site is good on old microprocessors etc.

The z80 versus the 6502

Simple z80, 6502 and 6909 computer designs

The development of the 6502

and this on the 70s and 80s personal computer boom

Historical computer designs index

The modern way of designing a microprocessor using VHDL

These days you normally turn a 7400 TTL design into a FPGA. Here a designer has emulated a FPGA with 7400 TTL

People still use DOS

The 16 bit (2 byte) microprocessor came out in the mid seventies


I have not been paying attention to what can be squeezed into the humble 8 pin DIL package. How about the NXP LPC810M, a 32 bit ARM microcontroller or the Microchip 128K X 8 serial SRAM? Are they the most complex chips put in the package?

Cloning electronics hardware

August 12, 2016 / consort3


There has been a renaissance in beer brewing in the UK and US. I think it started with the Campaign for real ale (CAMRA) in the UK and spread to the US where it is called craft beer.  Dissatisfaction with the products of the large breweries in each country started the trend. With 1400 breweries in the UK and about 4200 in the US it has taken off.–finance.html

I recently found the best brown ale,  Lewes Castle Brown by Harvey’s of Sussex. I must go and see the Widmer Bros Brewery in Portland, Oregon since it combines 2 of my interests beer and trains.

Maybe us Brits know something about beer

Beer and a statistics pioneer

Reddit beer forum

I am only going out for one


This guy likes beer


Taxonomy courtesy Ratebeer


June 1, 2016 / consort3

Sallen & Key slope

The humble unity gain Sallen and Key filter can be versatile. Don Lancaster’s Active filter cookbook showed me some of the filter shapes you could get. By varying the damping you can get upward and downward slopes to the frequency response . A nice article by Kenneth Kuhn showed me how to calculate the component values given the damping and the frequency.

At step 4, here is where I deviate from the above by using this website

Enter the capacitor values and it will compute R1 and R2 as 6.2k and 18K respectively, as per Kuhn’s analysis. Here is a Ltspice analysis of the circuit showing the 6dB peak of the underdamped case, even though the op-amp is configured as unity gain! By swapping the capacitors we get an overdamped case.


Good article on the above:

Or you could use a Quad style tilt equaliser, if your overall system has a problem.

Very nice article by the late great Chu Moy on headphone equalisers including the tilt type


Archive of Chu Moys Headwize site:

Good website on headphone amplifiers

Talking of headphones, Bose Qc35

Back to Sallen and Key. an interesting analysis:

The damping factor on the High pass Sallen and Key is perhaps more interesting in that the ratio of the 2 resistors determines the damping. Von Recklinghausen of KLH observed that the family of curves you get by varying one of the resistors could be used in a small vented box loudspeaker to get good bass by varying the bass boost. It will not handle large bass signals, but by varying the boost the drive unit is not overloaded. This is called dynamic equalisation and was used on the KLH 3, they called it their Analog Bass Computer.

The Analog Bass Computer concept is comprised of three basic elements: A variable gain equalizer with equalization slopes that are also dynamically variable, a threshold circuit to determine the levels at which gain and slopes are altered, and a transducer analog circuit that examines the power amplifier signal returning from the loudspeaker for evidence of thermal overload or mechanical fatigue. The analog bass computer is in essence, therefore, an equalizer that changes its equalization curve continuously over a wide range of levels to protect the loudspeaker from damage that might result if a simple bass-boost circuit were used

April 24, 2016 / consort3

Rare pigs

Unusual  rare cute pigs

The result of American efforts to create a pig with Hereford cattle markings, the Hereford pig originated in Iowa


The result of Danish efforts to create a Sandy saddleback, the Danish protest pig originated in Schleswig-Holstein


What would you get if you crossed the two? A White faced saddleback?

This one is so rare it was initially rejected by the Rare breed survival trust, thankfully now approved, the Oxford Sandy and Black


Not cute but rare and interesting the Ossabaw island pig

September 5, 2015 / consort3

Flying Scotsman

The Flying Scotman the Cornish Riviera Express and the Brighton Belle are featured on this:
The Trains That Time Forgot: Britain’s Lost Railway Journeys
Timeshift journeys back to a lost era of rail travel, when trains had names, character and style. Once the pride of the railway companies that ran them, the named train is now largely consigned to railway history.
Writer and presenter Andrew Martin asks why we once named trains and why we don’t do so anymore. He embarks on three railway journeys around Britain, following the routes of three of the most famous named trains – the Flying Scotsman, the Cornish Riviera Express and the Brighton Belle. We reflect on travel during the golden age of railways – when the journey itself was as important as reaching your destination – and compare those same journeys with the passenger experience today.
A glorious, evocative, journey back to a lost era of rail travel, when trains had not only names, but also huge character and style. Back to a time when, instead of buying a ticket for a journey, you booked yourself on a ‘service’. If you were travelling to Bristol, the fortunate passenger could choose ‘The Bristolian’; to Sheffield, ‘The Master Cutler’; and to Dover, ‘The Golden Arrow’.

The launch of a named train was, for the time, a highly sophisticated marketing tool. They attracted the discerning passenger by giving them a markedly superior product offering than the competition. Yet, once the pride of the railway companies that ran them, the ‘named train’ is now largely consigned to railway history. An astonishing three hundred and fifty named trains have come, and mostly gone, in this country. Trying to resolve the conundrum of why we once we were in love with named trains and why we aren’t anymore, noted railway writer Andrew Martin Andrew embarks on three railway journeys around Britain.

He follows the routes of three of the most famous named trains: The Brighton Belle, from London Victoria to Brighton; The Flying Scotsman, from Edinburgh to London Kings Cross; and The Cornish Riviera Express, from London Paddington to Penzance. The contrast between travel during the golden age of railways and what many would consider as the bland and densely packed passenger experience of today, is palpable. An un-missable programme for anyone who cares about our rich railway heritage.

Confusingly the FS term can refer to the train or  an engine. The engine had a special tender with a corridor so the crews could change without stopping. At some time they ran with 2 tenders.

New livery for the Flying Scotsman
The Belle is being restored:
One of the technical achievements enabling the Flying Scotsman to be non-stop was the water scoop, picking up water from troughs in the track. The last time the system was used was in 1968

I found this on a forum:
“In UK there were many installations of water troughs. Without research I know of ‘West Coast Route’ say 390 miles long at four locations between London and Crewe. On the ‘East Coast Route’ I think there were similarly about three. The Great Western used them but not the Southern. If you want I can research and list. I used to spend many hours at Bushey Troughs on the WCR, 12 miles north of London, Euston. I was just a few feet from the track and enjoyed the frequent passage of fast and slow, passenger and freight trains collecting water on the move. The scoop needed lowering and lifting with skill. The fireman would need to be quick turning a screwed actuator. At commencement of the troughs the scoop would be quickly lowered energetically by the fireman who would then watch the tender water level gauge to estimate when to start lifting the scoop. If the lift was late then there would be an overflow, washing coal off the tender and soaking un-warned passengers in leading coach compartments. If there were two engines they would arrange to collect in turn, requiring more skill and co-ordination between two firemen. The scoop was fitted with a deflector which assisted the passage of water into the scoop mouth. Water troughs were first used and invented by the London North Western Railway, a constituent of the WCR and at its time the largest Joint Stock Company in the world. On reflection I seem to remember a list of about twenty UK installations. Locomotives were fitted with large deflector plates protecting leading small non-driving wheels so that water from the collection activity did not wash lubricant from bearings. Diesels were fitted with steam heating boilers for train heating with water tanks. Early deliveries of some classes were fitted with scoops. I worked a lot on diesels but am unaware of the pick up equipment ever being used. Later deliveries came without the equipment and it was soon removed where fitted. Some equipment and buildings associated with trough installation remain in place”

Overflow from the tender (courtesy Jimquest)


The trains consumed so much water which weighed a lot, so that carrying it cut down the payload, hence the scoop idea. It  is rather similar to long haul flights today where they have a reduced number of passengers so they can carry more fuel. The idea of in-flight refuelling has resurfaced.

Whether one wants these long haul flights also depend on sleeping arrangements as well I would have thought. How about this for an idea:

With a re-jig of the aisles, the economy class layout is 1:2:2:1 twin module so that everyone has access to an aisle, the idea would work. I was unaware that the Douglas DC3 was originally conceived as a ‘sleeper’ A typical overnight trip would be Newark to Los Angeles in 14 hours 40 mins

Stage 1 Newark to Memphis 945 miles, Stage 2 Memphis to Dallas 418 miles, Stage 3 Dallas to Phoenix 886 miles, Stage 4 Phoenix to LA 357 miles Total miles 2606

They are providing a sleeper bus service from SF to LA

A further program in the Timeshift series covered the diesel engine and mentioned the Deltic diesel. A beautiful concept and the Type 55 was used for the Flying Scotsman.

I found this on another forum: If you ever get the chance to hear a Deltic at full speed, do. The turbo  is huge and turns 140,000 rpm at full speed. It creates an incredible  shriek that I’ve never experienced from any engine other than a Deltic, not  even the sound of a Formula 1 car turning 19,000 rpm can equal it.

Youtube has let me down, I easily found the Vulcan howl (see Olympus) But the Deltic howl is elusive If anyone has a recording please let me know. Imcidentally the opposed piston 2 stroke diesel concept has been taken up by a company called Achates who claim better fuel economy.

Trains and boats and planes


August 27, 2015 / consort3


With the total blog reads exceeding the height of Everest (these days 29029 ft) I thought I would regale you with a story of another high peak, Olympus, more specifically the jet engine that bears the name. It was used on the Vulcan and the Concorde.
Although not originally designed by him, it will always be associated with Sir Stanley Hooker whose autobiography “Not much of an engineer” is a must read for engineering students. He made his name by doing some small modifications to the Merlin engine supercharger, increasing the power by 25%. Then he came up with the idea of using 2 superchargers in series, effectively doubling the power at high altitude. Mind you, it took Hives, the boss of Rolls Royce to suggest using it in the Spitfire!

As part of his Merlin supercharger activity Hooker and colleagues came up with a formula to predict engine power. He then coined the phrase, the pen is mightier than the spanner.

Hooker was the engineering mastermind behind the Harrier Jump jet, the Concorde and the RB211 jet engine.

Those projects would not have happened without Hookers leadership.
Having made such improvements to the Centrifugal supercharger he thought he was one of the world’s leading experts but then in 1940 he met Frank Whittle who he realised knew more than he did about the subject, Whittle having used the Centrifugal type in his jet engine. The mutual respect between the two led to the Nene engine, a derivative of which powered the Mig15. How the Russians got the technology is interesting but Sir Stafford Cripps was naïve in specifying that they should not be used for military purposes!
Interesting discussion on this

One of the opposing aircraft to the Mig15 in the Korean war was the P80 Shooting star which was also powered by a derivative of the Whittle centrifugal jet. The T33 trainer which derived from the P80 was built in substantial numbers and still used the centrifugal jet as did the Mig17 which had an afterburner. Hooker helpied the Chinese with their copy of the Russian copy of the Nene 25 years after he designed it! He joked that the Russians had even copied the mistakes

The Nene was the “needle” engine to American engine makers especially after Cripps’ mistake.

It was not until I watched the Guy Martin documentary on the last flight of the Vulcan that I was aware of the howl

This is the man whose idea it was to use the Vulcan to help regain the Falklands:

My Dad was in the same squadron as Beetham, 214. Dad was one of the few Brits who crewed the Boeing B17, hence my interest in that maker.

Fantastic teamwork to make it happen, see Rowland Whites book Vulcan 607

It has been 40 years since Concorde entered service. I wish I had taken one of those cheap supersonic flights, so that I could say I have been supersonic. Interesting background article:

It is the 80th anniversary of the first flight of the Spitfire. Mutt Summers was the pilot. See his Wikipedia entry for how he got the nickname. He is second in the number of types flown with 366. More famous these days for his test flights of Barnes Wallis bouncing bomb prototypes. Good obituary here:
His bosses would listen to his pronouncements on aircraft and act. Amazingly Bill Waterton at Glosters was not so priviledged with the Javelin.

Talking of unsung heroes, this is Nasa’s Korolev

Korolevs masterpiece Sputnik 1 went into orbit on 4th October 1957 triggering the space race

Another unsung hero, the man who invented aviation glues

Female unsung hero,  aviation pioneer got pilots licence in 1911, aged 47

Another female unsung hero, Johanna Weber mother of Concorde and Airbus!

Unsung hero aviation pioneer George Cayley

More aviation unsung heroes including Geoffrey Taylor who was Booles grandson and Hookers tutor.

Not aviation but worthy of a mention, Nils Gustaf Dalen, Nobel Laureate and inventor of the AGA cooker, being working class we had its cousin, a Rayburn!én

Unsung hero of the Dieppe raid

If you are an aviation enthusiast you might want to fly on Russian metal:

Methinks Hooker would have been proud of this  invention:

There is an intentional hint of a paean to leadership here, cometh the hour cometh the man.

July 15, 2015 / consort3

Ancient civilisations mystery

Updated 6 June 2016

I recently did a tour of the Scottish Islands and was struck by the henges erected 5000 years ago. A cult swept through Britain at the time. The climate was more favourable in the North then. But how did they transport themselves between the Islands and the mainland? The guide suggested animal skin boats similar to todays Coracles and Currachs:

I remember Tim Severin’s re-creation of St Brendans voyage in a Currach

The neolithic people were smarter than we give them credit for. A recently discovered example are the stone age man made islands in Scottish lochs.

Civilisation is older than you think

Interesting documentary on this

Drought affected the Indus civilisation

The Indus civilisation is older than first thought

Lost wax casting process is 6000 years old

Deciphering the Indus valley script

This civilisation was unknown to me

How the Vikings carved up England

The mystery of the Etruscans where they came from etc.

From 1565 to 1815 Spanish Galleons traded between Spain and the Philipines

Interesting theory about the Luwians (no, I had not heard of them either)

More on the Sea People theory

Another civilisation I had not heard of, the Kazars

Alcohol and civilisation 9000 years ago

Going back to the boat problem, one of the reasons the Phoenicians became an important civilisation were their longships

However the technology to build these was lost after the 3rd punic war:

Development of the Greek Trireme ship

What the Aztecs can teach us

Medieval Shangri-la or Utopia

Interesting Myceanean find at Pylos