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Craig Sawyers

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Craig Sawyers last won the day on November 23 2022

Craig Sawyers had the most liked content!

About Craig Sawyers

  • Birthday 03/02/1956

Profile Information

  • Location
    Oxford UK
  • Gender


  • Location
    Oxford UK
  • Interests
  • Occupation
    www.tech-enterprise.com , LinkedIn profile
  • Hobbies
    Copious squared
  • Headphones
    Stax Lamdas, SR007Mk2 DT990, K701, Etymotic FR4P, Old Koss ESP9
  • Headphone Amps
    KG Triode, Dyna-something, KG BH, T2 clone completed and sounding stunning
  • Sources
    Tent Labs, Meridian and Cambridge Audio CD, Garrard 401/SMEIV/Zu DL103, Logitech Transporter, Tortuga Audio LDR passive pre
  • Other Audio Gear
    Linkwitz LX521.4 speakers

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  1. Some British guys blowing up small electrolytic capacitors by putting too much voltage on them, in slow motion. Like they said "don't try this at home"
  2. He cut down on the booze in his later years. His last stage play, Private Lives, he did stone cold sober. He says in his diaries that it was the scariest thing he has ever done - everything you have ever seen Burton in, movies, plays etc he was boozed up just enough to overcome stage fright, without losing the ability to act. Acting: pretending to be someone else, for money.
  3. Burton died at the age of 58 from a cerebral haemorrhage, the cause been a life of chain smoking and a gargantuan amount of booze. I've read his diaries, and at one stage he congratulates himself for cutting down - from three bottles of vodka a day to just one. It is a wonder he lasted to 58.
  4. I seem to making a habit of posting about theatre trips! Went to the National Theatre in London to see The Motive and the Cue. This was about the staging of Hamlet on Broadway in 1964, starring Richard Burton and directed by John Gielgud. It was really about the way the two clashed during 25 days of rehearsals - Gielgud's interpretation was very mannered and formal (he performed Hamlet 500 times!), and Burton's was fiery and emotional. They eventually found mutual respect. Directed by Sam Mendez, and starring Mark Gatiss as Gielgud, Tuppence Middleton as Liz Taylor and Johnny Flynn superbly as Burton. https://www.nationaltheatre.org.uk/productions/the-motive-and-the-cue/ https://en.wikipedia.org/wiki/Mark_Gatiss https://en.wikipedia.org/wiki/Tuppence_Middleton https://en.wikipedia.org/wiki/Johnny_Flynn What is interesting is that Flynn is the same age as Burton was in 1964, and Gatiss at 56 is almost the same age as Gielgud, who was 60 in '64. Likewise Middleton - Liz Taylor was 32 and Middleton is 36. So the ages of the main characters were very true to life. If you want to see what the Broadway play with Burton was like, YouTube is your friend
  5. It is summed up in the last sentence: "I’ll choose magic, if only it didn’t come at such costs". And that sums it up - everything Dyson is a major investment. About the most affordable, and something I bought for MrsS, was a Dyson Supersonic hair dryer. It is still not cheap, but is is quiet, powerful and light. But would I spend three times that for a Dyson vacuum cleaner? Well no. I've just fixed our twenty year old Sebo with a new mains lead from eBay (the old one was chewed), and some duct tape over a hole in the base. It does the job, and the green thing is to keep it going until is really does keel over.
  6. Here is an interesting figure The bottom axis is in kPa-cm. Atmospheric pressure is 100kPa. Let's say that we use a shoulder washer that goes into the ceramic insulator 0.5mm, so the overall arcing distance is 1mm, or 0.1cm. So we are interested in 100 x 0.1 = 10 on the horizontal axis. That says that the breakdown voltage is about 5kV - so we should be OK? Well no. Those curves (Townshend curves) are taken between two parallel plates, so an ideal measurement arrangement - the result of a very careful experiment. The case of a small diameter screw thread, which has voltage stresses from each thread peak reduces the breakdown voltage significantly. And it is uncontrolled - tiny bits of conducting swarf and other grot possible too. So an 0.5mm insertion into the ceramic is getting marginal for 500V. Increasing the insertion to 1.5mm gives an arc gap of 3mm (0.3cm), giving a (ideal, parallel plate) breakdown voltage of about 10kV. Even if this was degraded by a somewhat outrageous factor of 10 (1kV), we are still safe at 500V. Which is the basis for using shoulder washers that are as long as reasonably possible
  7. because the OD of the washer extension is larger in diameter than the hole in the bracket and PCB, assuming they are nominal clearance holes for the fixing screws.
  8. Found the spec sheet in my T2 parts folder - looks like I used 7721-3PPSG . That has an extension of 3.81mm (1/8") and that clearly worked. Again Mouser - they have 11,500 of them in stock.
  9. You have that right - the T2 has some fearsome voltages knocking around - and detail for everything is the name of the game. To make the umbilicals connecting the power supply to the amp chassis took 8 hours solid work. That is typical of the length of time needed to not only make it work, but continue working as the months and years go by.
  10. Regarding transistor mounting. I'm thinking back a looong time to when I built mine. I used steel screws, because I could not get enough torque on plastic screws (I use a torque screwdriver and read the data here https://www.onsemi.com/pub/Collateral/AN1040-D.PDF ). But the trick is to use the AAVID long penetration washers. You need enough length to go through the TO220 tab, and penetrate most of the way through the 4171G insulator. Now the problem is that the thickness of the tab is extremely widely specified - somewhere between 0.5mm and 1.39mm. I've done a straw poll of TO220 devices I have, and the vast majority are between 1.25mm and 1.3mm thick. My 4171G insulators are actually 2mm thick (at the top end of the tolerance; they are nominally 1.778mm (0.07") +/- 0.254mm (0.1"). So mine are towards the top end of the tolerance band. Anyhow, it looks like the AAVID 7721-13NG (Mouser has 8,000 of them) is the man for the job. I can't find the remainder of the ones I bought to check, but I think I used those. The extension is between 2.71mm and 3.26mm. You need to check your tab and insulator dimensions, but under most circumstances the shoulder washer will go through the TO220 tab and most of the way through the 4171G. If the tolerance stack goes against you, that shoulder washer might actually protrude from the bottom of the 4171G. If that is the case you absolutely must trim the end shorter. Otherwise you won't make thermal contact between the transistor and the heatsink. That will enable you to use steel screws and nuts (don't forget the lockwasher!). Oh - and you absolutely must use heatsink compound! Craig
  11. I never thought this ridiculous product would see the light of day. What an awful concept. But Dyson have had much more serious products bomb. They developed a washing machine. Normally washing machines have a big block of concrete in the back to stop the spin cycle from making the machine jump around and shake itself to bits. Which is why washing machines are stupidly heavy. Dyson came up with a contra rotating drum and active stabilization. A superb idea - much lighter weight, quiet (because Dyson understand motors) - and so punishingly expensive that very few bought it. Let's not forget that James Dyson's first product was the Ball Barrow - the usual wheel on a wheel barrow was replaced by a ball - so you could turn corners more easily. Of course lots of companies make them now because Dysons' patent on this is long expired. But typical of the man - he took the concept of a ball on an axle to boat launching and other marine activities. But the product that came to define him was the cyclone vacuum cleaner. Developed in his back room of his modest house. Then Hoover took his patent, copied it and started making them. Dyson fought back, and won with massive punitive damages. But the reviews have it right for the daft headphone/filter thing. All Dyson's current products are to do with motor technology and filtration, and excellent product form and feel. And this massive headphone construct with the mask is no exception. For all its weight and laughable appearance, it is superbly designed and built.
  12. Actually two days ago. Went to see a play at Chichester, in the tiny Minerva theatre https://www.preevue.com/projects/minerva-theatre . The play was called 4000 miles, and we really went to see it because it has Eileen Atkins in it. A titan of theatre and movies. She was splendid, but looked a bit old (the character was of an old woman). It was only when we got home and checked: 88. Still treading the boards at 88! Hell she started as a professional leading actor in 1953 - three years before I was born. This is she - courtesy of Wikipedia https://en.wikipedia.org/wiki/Eileen_Atkins
  13. The Mad Max beyond Thunderdome movie was released (good grief) in 1985 - so Turner was an awesome looking 46 year old. Gibson was a whole lot younger at 29.
  14. We expect our icons to go on forever, and are shocked when they grow old and shuffle off. RIP Tina. On another RIP, Professor Vicky Neale at Oxford and a specialist in number theory, a broadcaster with Radio 4's More or Less, has died aged 39 from a rare form of cancer (and fuck cancer royally) https://people.maths.ox.ac.uk/neale/
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