Member postings for Geoff Theasby

"Rule Britannia"!

Geoff

Regarding LED lamps, this is not strictly relevant, but the info contained may be of help to someone, Everyday Practical Electronics, Sept 2016, page 30 et al. This is the current issue. Build a party strobe light, using a mains powered LED floodlight bought online for about £10.

Geoff

Andrew, indeed. Part of the problem with practical analogue filters for amateur purposes is finding or creating a design which could be built with easily available components, esp. capacitors. As you say, digital filters are, by contrast, extremely good and unbelievably effective.

Ian, Yep, the very same! Twice as old now and twice as ugly, but no wiser (See current Club News)

Geoff

Andrew, indeed. Part of the problem with practical analogue filters for amateur purposes is finding or creating a design which could be built with easily available components, esp. capacitors. As you say, digital filters are, by contrast, extremely good and unbelievably effective.

Ian, Yep, the very same! Twice as old now and twice as ugly, but no wiser (See current Club News)

Geoff

Andrew, some of my radio gear has different filters available. Whilst being 'different', the actual sound and filtering effect are very similar. In an undemanding condition, perhaps so. Maybe not something we actual mortals need worry about overmuch. I built a Comb Generator, and wrote it up for PW. It used the propagation delay between gates of an IC to generate a signal going into the UHF region with a 10 MHz cheap crystal,

Geoff

Hmmm, no it doesn't! Anyway, as a practical radio user, I know that to transmit a true square wave, as in keying Morse code, you need a circuit that will respond without rounding off the corners or spreading out the signal,. This means creating a wider and wider bandwidth in order to accommodate all the higher harmonics, thus getting further and further away from the ideal. Too square and it will 'ring' or oscillate at the 'corners;' of the waveform, giving 'key clicks'. Too round and it will sound muffled and indistinct.

Also, re PW, they also do CDs of collected simple articles and projects, plus two books on Technical for the Terrified, etc.

Muzzer, you too, eh? Join the club! Rob Mannion was giving a talk at Otley Radio Club, and recognised me in the audience. I had to stand up and take a bow!

John, I never heard of a Dirac pulse before, although I knew who he was. Now, having read it up on Wikipedia, my head is spinning, but a picture is worth a thousand words. Just as my Geometry teacher said, "a line has length but no thickness," a Dirac pulse is one occupying zero time with a 100% energy content. Simples! Real life is not so simple though. Gosh, the things I learn in Model Engineering!

Bandersnatch, I have a small collection of books of this nature. Inc. one on how wonderful the new material called 'Radium' is! One on photography from the late 1890s, how to make your own 'Televisor' etc.

Geoff

If you want to understand simple electronics, Practical Wireless is good. Everyday Practical Electronics is too, and they produce "Teach Ins" on CD covering various aspects of electronics. PW is mostly amateur radio, but the same principles apply, and EPE is mostly microprocessors, which seems an overcomplicated response, but, I was brought up on valves, and regarded transistors with suspicion for many years.

If you want to build projects that work, the RSGB RadCom, again amateur radio, publishes work of a high standard, is peer reviewed and has access to real experts in the field, inc. a contact point with the IET.

Maplins sell good guides to electronics, depending on your interest, and the radio control magazines and associated model engineering societies like the Gauge 1, Gauge 3 and 2 1/2 inch gauge society cover the subject at times.

Geoff

Tim,

I once discussed metrication with an American who couldn't agree that a 1 inch diameter steel bar was also 25.4 mm across, or that you could produce metric items on an Imperial lathe. See upcoming Club News 4542.

Geoff

Martin,

I caused this one myself many years ago! My Triumph Herald developed a leaking fuel tank, so, in order to drain it prior to removal and repair, I applied a spanner to the drain plug, and when I applied pressure the whole drain pipe twisted out of the tank and dropped a couple of gallons of petrol into the plastic bowl hurriedly placed beneath. Petrol and polythene...? Not only that, but the petrol then began dissolving my Dad's tarmac drive!

Geoff

Martin,

I caused this one myself many years ago! My Triumph Herald developed a leaking fuel tank, so, in order to drain it prior to removal and repair, I applied a spanner to the drain plug, and when I applied pressure the whole drain pipe twisted out of the tank and dropped a couple of gallons of petrol into the plastic bowl hurriedly placed beneath. Petrol and polythene...? Not only that, but the petrol then began dissolving my Dad's tarmac drive!

Geoff

Hi all,

I couldn't find it last night, it may have been on a computer since demised, although I kept the hard discs and can access them. I'll try again today, or at least find out who published it and when. Meanwhile, the Wikipedia entries are good, I even learned a few things myself!

Geoff

Swarf, Silly... The N/BNC/TNC/C connectors were indeed named after their designers Neil & Concelman. I wrote an article for the Amateur Radio press on this basis, many years ago, and if you will allow me time, I will resurrect it for you.The idea is that, not only are they mechanically rigid & stable, but that they *look* like an ordinary piece of coaxial cable to the passing signal, ie., they are 'constant impedance' as well as coaxial. (Signal wire runs through the centre of a round, wire mesh, earthed screen) NB, red insulation on 'UHF' connectors is a No-No. Bin them! White insulation is better, preferably Nylon, or PTFE, but that connector is not a good one anyway, above about 30 MHz.

Geoff

Weren't round teabags introduced by BR on this basis? Mind you, one MD of mine never bothered about minor theft, he said (Specifically about ball pens) that "eventually you reach saturation". This may have been OK for a small satellite communications company, but could otherwise have resulted in BR supplying half the nation with tea! AND the satcoms company went bankrupt...

Geoff

Having an understanding wife...

Mike, I notice you don't have any oil holes in the main bearings. Perhaps a 1mm drilling from the top, with a countersink to hold a drop of oil?

regards

Geoff

Mike, I notice you don't have any oil holes in the main bearings. Perhaps a 1mm drilling from the top, with a countersink to hold a drop of oil?

regards

Geoff

Thomas, look in Smart Tools for several Android apps, inc screw thread details.

Geoff

Thomas, look in Smart Tools for several Android apps, inc screw thread details.

Geoff