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cliff park

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    : Great Yarmouth

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  1. Just in case it helps, MDF will reliably take a thread. Obviously not for heavy loads, nor for repeated screwing in and out, but for an assembly like this it would be better than woodscrews
  2. I have in the past used a drop shelf instead of a raised one. Obviously the shelf length must be less than the floor to layout height. It does restrict the doorway by the thickness of the shelf, say 4", and it helps if there is nothing sticking up on the top of the shelf, say telegraph poles, loading gauges or buildings. But for the 'tidal creek ' I would have thought it would work well. The barrel bolts can also be used to operate a relay so that when the shelf is down track either side of the shelf is dead
  3. I have tried to put some notes together to answer the kind of questions that come up for people who have no electronics experience. LEDs and resistors are cheap. You can experiment without worrying what it will cost. Resistors are robust, mechanically and electrically, LEDs are not. LEDs can be destroyed by heat, don't solder too close to the body, and don't keep the iron there for too long. A good idea is to use chocolate blocks to try different resistor values, and solder once you're happy. LEDs are polarity sensitive, resistors are not. It does not matter a scrap which leg of the LED the resistor is in, BUT if you always put it in the same leg it makes life easier when wiring them up. LEDs with a resistor in series will not be harmed if connected the wrong way round, they just won't light up. Resistors are measured in Ohms, symbol Ω. If using resistors in series simply add the values together, so a 10KΩ (ten thousand ohm) plus a 10KΩ in series equals 20KΩ. Putting resistors in parallel is more complicated, but for this simple example a 10KΩ and a 10KΩ in parallel equals 5KΩ. Resistors come in preferred values. So you will not find a 5KΩ resistor, you must use 4·7KΩ or 5·6KΩ, but don't worry, when it comes to LED brightness those difference will not make a huge difference. You will almost certainly only ever need ¼ watt, the power rating, as the current used by LEDs is very small. Start off with high value resistors, the LED will be dim, reduce the resistance until it looks about right. Don't forget an LED sitting on the bench looks different once installed into a building.
  4. As another (retired) electronics engineer I suspect that the sledgehammer brigade are just frightened of things they don't understand. I have told this story on here before. My first experience with a PAT guy was when we brought in external contractors, instead of doing it ourselves. He cut the mains plugs off half a dozen monitors and condemned them because there was no earth continuity to a metal screw he found in the case. They were all double earthed with no earth connection.
  5. When I worked in the tech department of a high school we had lots of problems with photos of projects stuck into folders then having to be sent away for adjudication. On arrival lots of the photos had come free from the folders. After experimenting we found that of all the available brands Pritt Stick was the best and lasted the longest. Eventually, about 3 years, even they dried up, but that was paper on paper.
  6. Saturday was market day in Norwich in the 1950s, I can remember as a child vast numbers of cattle being herded through the streets down to Trowse station to be loaded on the trains. I assume it had always been Saturday.
  7. Not easy to see your circle, so if you don't mind I have highlighted it
  8. They certainly use that trick to spray car panels and other metal parts. A place near us specialises in spray painting office furniture, frames for school desks etc, and I've seen that in action. Quite remarkable the way the paint is attracted to the metal.
  9. Just noticed this post. Try asking in the 'Electrics non-DCC' forum. Lots of stuff on HM6000 units there
  10. So the BT one and the APD one together add up to 1.15A approx. But this is only when 'loaded 'up. Ie most of the time they take negligible current. It wouldn't hurt to uprate your cable if you have multiple sockets, there is always the chance somebody will plug a fan heater or something similar in, or at least make sure the fuse in the plug is 3Amp.
  11. A little GPO story. Many years ago, when telephones and Royal Mail were all GPO, a local Telephone overhead gang had to renew a rotten pole, which had a post box mounted on it. So they contacted the local postmaster to send someone with a key as the hoops which held the box on had nuts on the end inside the box. By the time they had disconnected the dozen or so telephone lines and got everything ready to go no key had turned up. So the decision was made to fell the pole, saw it off just above the post-box and knock the hoops upwards to remove it. Slide the hoops onto the new pole, place in ground, add steps, arms, reconnect all the customers, great. It was only as they drove away they realised because the new pole was slightly thicker the letterbox was now ten feet off the ground.
  12. Don't forget that an ammeter is in series with the supply. So if you feed the ammeter through a bridge rectifier then the supply downstream of that will always be one way, you would need another reversing switch after the ammeter. Digital meter sounds the way to go. How about two 4mm sockets in one leg of the feed, plugging the meter in, in current mode, would read whichever way the current is flowing. You could then bridge the two sockets, short link of wire with a 4mm plug on each end, and remove the meter completely for use elsewhere when not required.
  13. One point that has always struck me is when photographing anything moving, or in the case of a model vehicle, potentially moving, the subject should look like it has somewhere to go. So for the two photographs of the goods train, photo 1 looks like the train is moving into the space on the right hand side, whereas in the second picture it is going to run out of track. I'd be a little worried about your photographer friends, if they become very good you could be out of a job.
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