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Member postings for Anthony Knights

Here is a list of all the postings Anthony Knights has made in our forums. Click on a thread name to jump to the thread.

Thread: The Workshop Progress Thread 2021
05/03/2021 17:22:19

I have now finished making enough components of the Stewart Hart beam engine to be able to fix them together to see what it looks like. (Impatient person that I am). Made a rough looking flywheel from MDF just to get some idea of dimensions when it came to making the plinth. There is still quite a bit to do, but I've already got a little guy to operate it when it's finished.

beam eng1.jpg

Thread: Skynet is Coming
28/02/2021 08:15:35
Posted by Hopper on 27/02/2021 09:19:49:

Then the old one is recycled. It's green, innit? Take a look at BMW recycling two year old cars and cry:

It would probably be "greener" to repair it, but in these days of double sided circuit boards with minature surface mount components that I can barely see, let alone identify, it's not really possible. It's 12 years since I retired so that's an epoch in the electronics game. Well before then, I stopped taking the likes of "Practical Electronics" when most of their projects comprised a PIC and a page of code. I have to admit that towards the end of my working life, I too became a board/equipment changer, but according to my friend who is still working, the new "engineers" can't even manage that.

27/02/2021 02:42:55
Posted by SillyOldDuffer on 24/02/2021 17:58:56:
Posted by Frances IoM on 24/02/2021 17:42:07:
The point I was trying to make is that the cost of these small PIC-like chips are very small + total cost considerably less than any design that requires components that cannot be autoplaced - the ability to use compute power to avoid components such as large value capacitors is another significant cost saving - added to these is the stocking cost of a single component vs many.

And not just small PIC-like chips. Rather powerful microcontrollers are, ahem, cheap as chips. Plus Field Programmable Gate Arrays and similar technologies capable of being mass-produced and told what they are later. As these things cost about the same as a discrete components of the same size and can do much, much more, there's been a rapid move away from discrete components. Many of them are getting difficult to find.

Bring back ECC81s and 6V6s. It's not proper electronics unless it glows in the dark and smells of hot Mullard!


These super chips might be "cheap as chips" but if you try to buy a new control board for say a washing machine, you will probably find the cost is not far short of a new machine. At least with discrete components, there was a good chance of effecting a repair. (Probably why they have gone down this route, or am I just being paranoid?)

25/02/2021 04:34:01

Valve TV's. Them were the days. A colour set had valves the size of jam jars, mains connected to the chassis, a lethal 25Kv final anode voltage and were a 2 man lift. How we survived without H&S I'll never know.

24/02/2021 14:13:46
Posted by Frances IoM on 23/02/2021 19:47:40:
No it sounds like a simple PIC processor - they will cost less than your 2 transistors which would probably need a capacitor for timing purposes (the latter being guaranteed not to last 10yrs unless quite expensive. Since you knew what it had to do program your own PIC
Great idea.I'll buy a PIC programmer and teach myself how to program a PIC. I might as well bin my box of electronic components at the same time.

Thread: Where to find a *good* optically flat mirror?
24/02/2021 09:21:21

Sheer speculation-how flat is a hard drive disk?

Thread: Skynet is Coming
23/02/2021 18:26:07
Posted by Nick Clarke 3 on 23/02/2021 11:17:03:

The most interesting part about this is the data retention time, presumably MTBF, of 10 years - so the design life is only 10 years?

It's worse than that. I'm told the device is 4 years old. If the microcontroller chip is faulty, there is no point replacing it, because I have no way of knowing how it was programmed. It may even have been programmed to commit suicide once the warrantry period was over. The manufacturer does not list the pcb among the spare parts, so it's bodge time. The simplest one is to bypass the relay driver transistor with a switch and control de-icing manually. Otherwise, build a trigger circuit with some hysteresis in it to monitor the ice sensor and drive the relay with that. Isn't technology wonderful.

23/02/2021 11:06:16

An example of technology for the sake of it?. Yesterday I was given a defunct dehumidifier, which appeared to work, but the compressor wouldn't run. Interesting starting arrangement with the start winding in series with a positive temperature coefficient resistor. Memories of the de-gaussing coil on a shadowmask crt. There was also a fusible link in the common supply, but both appeared OK.

The fault was traced to a small PCB, whose function was to interrupt the compressor supply, when a sensor told it the condenser matrix had iced up. Found the relay and its driver transistor which in turn was controlled by a 20 pin IC. Looked up the type number and came up with the following info (I have deleted the chip type number)


I could probably replace that lot with a couple of transistors and a few resistors. Is this just a lazy designer or was he told " We've bought 1/2 a million too many. Can you get rid of them for us?"

23/02/2021 10:20:52

Back in the 70's the company I worked for used to buy CCTV cameras and monitors from Japan. Every item had a user manual (more a 4 page leaflet actually) but came complete with a circuit diagram. Of course, that was back in the day when it was possible to repair stuff on site.

Thread: Guiness world record?
18/02/2021 20:46:23

Velcro is easier than laces.

18/02/2021 18:10:50

Hello Mr Pete Smith. What you need is one of these;-



My daughter bought me one, now I'm unfortunately on my own. I couldn't manage without it.

Regards Anthony

Thread: BA threads
31/01/2021 22:43:05

Thank you peak4 for an interesting read. So we copied the 47.5 degrees and all the fault of the Swiss.

31/01/2021 13:40:12

I am puzzled by the 47.5 degree angle between the flanks of BA threads. Was there some obscure mathematical reason for this value, or were the design committee split as to whether to use 47 or 48 degrees. Whatever the reason, I don't see how half a degree would make any difference one way or the other. If it was up to me, I would have chosen 48 degrees, purely on the KISS principle. 48 factorises to 3 x 2e4 and would be really easy to set up for grinding threading tools. Forgive me for asking stupid questions, but I spent my life as an electronics engineer, where one learns to think logically and learns something new every week.

Thread: Coronavirus death stats
17/01/2021 10:27:21


Hopefully I won't now be dying from covid, although I do have other conditions which could see me off.

Thread: New Covid Rules
13/01/2021 08:54:57



Edited By Anthony Knights on 13/01/2021 08:56:42

Thread: Angle grinder cut off stand
11/01/2021 14:39:51

This is an Aldi cut off stand, fitted with a 115mm angle grinder. I used it a lot until I bought a "Fermi" band saw. Still used for cutting HSS blanks. It has a crappy vice arrangement, but at least has a cast iron baseplate, rather than the steel pressing that a similar machine sold by Machine Mart had.chopsaw.jpg

Thread: Humbrol Enamels
10/01/2021 10:38:04

Thank you for your replies gentlemen. I'm not bothered about any matting effect as I will be painting figures and most clothing and skin is not glossy.

10/01/2021 07:58:38

I was recently given a large number of the small tins of Humbrol enamel, most of which have never been opened. On the tin it says to use Humbrol thinners. Is this a special composition, or would white spirit or some other solvent work? It has been many years since I made plastic models (moon shot) and I'm afraid I can't remember what I used back then. It is presently so cold in the workshop, I thought I would try something I can do in the house.

Thread: A white xmas
29/12/2020 10:52:42

I woke up this morning to snow on the ground (North Yorkshire). The freezer has needed de-frosting for some time, so I bagged up the contents and dumped them outside. Then did the defrost (aided by a heat gun). Freezer is now refilled, neatly for now, but it won't last. Another round tuit job done.

Thread: Stewart Harts Grasshopper Beam Engine
29/12/2020 08:48:58

Hi there. I am building the same engine and Stewart sent me the original plans. Does this Help?


Regards Anthony.

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