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2mmMark

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    http://www.nn3.org

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  • Location
    A stone's throw from 70B
  • Interests
    2mm Finescale, Nn3 narrow gauge

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  1. Weeds, you say? Well... 2mm scale, 6.5mm gauge, so unfortunately not eligible as not standard gauge. Strange rules.
  2. Rummaging through my box of miscellaneous electronic components, I found a little digital LED voltmeter, 0 to 99.9v range plus a strip of PCB. A little while later I had a useful track tester for 9.42mm and smaller gauges. The attached photos should be reasonably explanatory. I think I got the meter from eBay. It's polarity sensitive which is actually a benefit as it shows up any crossed feed wires and if the controller is wired up to the "right hand rail positive" convention. The insulating gaps on the PCB were simply cut with a scriber. I did isolate the fixing screws of the meter but it's not strictly necessary, just good practice. It was tempting to cut the strip a bit shorter but I realised that having it a bit longer allows it to reach down into restricted access spots. The contacts are a couple of bent-over strips of nickel-silver.
  3. A lot of people will indeed stay at ohm.
  4. Thinking laterally, might this help with social distancing at exhibitions?
  5. if you do use the Guideline Publications website and register to buy, a tip - it only allows simple passwords containing A-Z, 0-9. No special characters allowed
  6. One of the things I've been intending to do is provide an integral controller for British Oak. For some time now, I've been trying out various small and inexpensive PWM speed controllers. There are a wide variety now available, sometimes also labelled as LED dimmers. The most useful I've found are the type called "Mini DC Motor Speed Control Driver Board 3V-35V 5A PWM Controller / LED dimmer" or some variation thereof, usually costing between £3 & £4 from a UK seller on eBay, cheaper from overseas. It's important that the controller has a PWM duty cycle of 0% to 100%, which means that at the lowest setting, no power is applied to the track. Some don't go right down to 0% which can leave a small voltage present causing some motors to creep. If you're very interested in PWM, then a pretty good explanation can be found here https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019OkFSAU Suffice to say that the controllers I've used give a precise degree of control, very good slow running and don't cause any noticeable motor heating or noise, unlike the feedback controllers which rely on low voltage AC input to provide a waveform at 50 or 60Hz. These controllers typically have a PWM frequency of 10KHz and require a DC feed. This means they can be used as battery controllers if necessary. For this application, the control pot usefully includes an off switch. Ths photo below gives some idea of the size. Being a bare controller, a reversing switch is required. For British Oak, I tapped into the 12vAC feed already provided for the plug-in controllers I use, like the Pentroller. The AC feed is taken to a small solid state bridge rectifier (the black box at the bottom of the case) and from there, the rectified feed is fed in the controller, which has screw terminals to make the job easy. The output from the controller is taken into a DPDT reversing switch with a centre-off. This serves to isolate the controller when a plug-in unit is in operation. If this is not done, there is a strong possibility the two controllers will interact with each other. Just to be on the safe side, I added some sleeving to the terminals of the rectifier. The controller also has screw terminals for the output. The wiring follows my particular convention of red & black for track power, green for AC and in this case I used orange for the DC where the polarity is changed by the reversing switch. It all fitted into a small project box which is screwed to a convenient location in the fiddle yard. Incidentally, those who joined in the 2mm VAG Zoom conference the other day will have seen an unusually tidy workbench. Below is much more typical, although there's actual bench still visible, not always the case... Mark
  7. All three arrived this morning so if you have a VL subscription, it's probably in the UK postal system. I also got the email with the link to a Zinio online copy. I did try it but it confirmed my view that Zinio is a slow and clumsy system which is best avoided. A simple PDF download is a much better option, although granted it's open to abuse by people sharing the file.
  8. ...just like buses, you wait ages and then three arrive at once... I'm more than usually grateful to all those who made this happen.
  9. Enough to fill a special edition MRJ 278½
  10. Not if they are glued and sealed into clumps as I suggested.
  11. How about adapting the technique of making static grass clumps? Spread some PVA glue onto waxed paper in the appropriate shapes then sprinkle on the relevant bits of swarf. Sealing the scrap clumps with a coating of dilute PVA as you would with ballast ought to insulate them. Then paint to suit, peel off the paper and glue into place. As for material, the shavings generated by using Olfa P-cutter blades on plastic sheet could be useful. Sawdust from a coarse saw blade might also be suitable.
  12. I got caught out by the change to 4-issue subscriptions. I found a renewal form tucked in 276 that I'd overlooked so re-subscribed very close to the due date of issue 277. Everything went fine. 277 was with me the same time as everyone elses.
  13. The interesting thing about the GE section of the Eastern Region is that it was extensively dieselised well before the Beeching cuts. This meant it had a great selection of the various 1st gen mainline locos and also a healthy variety of various shunters. For a brief but happy period for modellers, it was a traditional "common-carrier" railway. We're fortunate that Dr. Ian Allen was around to capture it. A good DVD on traditional freight operation in the region is this: https://transportvideo.com/product/pick-up-freight/ Mark
  14. "These newsagents are small, the ones outside are Biggar"
  15. Perhaps see if anyone makes etched brass letters, which you could polish up to make the pub name. A coat of varnish would be needed to stop them tarnishing.
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