I am always tweaking this blog. Unfortunately I tend to edit existing posts, so it is worth re-checking pages you are interested in, if you have visited before.
- TTL & Microprocessors
- Sallen & Key slope
- Rare pigs
- Flying Scotsman
- Ancient civilisations mystery
- Mystery of the Princes in the Tower
- Aviation mysteries
- The Maks
- Renaissance ramblings
- Raspberry Pi Part 2
- Simple Twin T oscillator
- MR16 Led bulb problem
- Darlington Pt 3 Serendipity
- Hi fi humour
- Cost effective darlington amp Part 2
- Raspberry Pi
- Metal dome tweeters
- Orwell festival
- My new amplifier
- active and passive elliptic crossover
- Car & plane concepts
- Warnock’s dilemma
- simple cost effective darlington amplifier
- overclocking the 555 timer
- Rhythm of the rails
- Mission Freedom & AR48LS
- 741 and some history of technology
- Fixing the 42PF7520D
- Pioneer Powerbass
- 3rd order low pass filter table
- X-max problems?
- Tweaking the DAP D3109
- LS3/5A Inspiration
- Homage to Tannoy
- W6-1139 & TM1A compact 3 way design
- Tweaking the Mission 762
- Loudspeaker projects
TTL (that is transistor – transistor logic) is 50 years old
Good article on the history of TTL
A 4bit microprocessor built in TTL
An even simpler TTL processor
A more complex TTL microprocessor
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
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
People still use DOS
The 16 bit (2 byte) microprocessor came out in the mid seventies
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.
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
I am only going out for one
This guy likes beer
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.
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
Talking of headphones, Bose Qc35
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
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
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
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!
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
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.
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
Another unsung hero, the man who invented aviation glues
Female unsung hero, aviation pioneer got pilots licence in 1911, aged 47
Unsung hero aviation pioneer George Cayley
If you are an aviation enthusiast you might want to fly on Russian metal: