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  1. Nick Mitchener

    Source of Bench Mounted Pulleys

    I was brought up with cramps. Not sure if it is a regional thing. We had some pretty hefty ones where I worked.
  2. Nick Mitchener

    Source of Bench Mounted Pulleys

    I've overcome that by putting the pulley on a bit of wood and clamping the wood with a G cramp.
  3. Nick Mitchener

    Source of Bench Mounted Pulleys

    We bought some cheap ones, black with red wheels. The axles were hollow brass cylinders, made from rolled sheet no join. They started failing pretty quickly. I modified them by fitting a machine screw and locking nut through the axle and they have been fine since, still much cheaper even with...
  4. Nick Mitchener

    Grant JB1 waterbaths with plastic lining

    Perhaps you could help me by getting the dimensions I need as I'm no longer at work? I'd like the thickness from inside the bath to the outside, plus the internal legth and width. I reckon we could get a plastic channel profile that would fit, cut mitred joints and seal it.
  5. Nick Mitchener

    Grant JB1 waterbaths with plastic lining

    These plastic linings seem to go brittle at the top and a bit of rough handling can leave open holes where water could get down to the electrics. Grant have no more liners abailable so I can see a lot of baths being made unusable by this fault. It occurs to me that there must be a way of...
  6. Nick Mitchener

    Dynamics Trolley wheels

    One option that comes to mind is convert them to 4 wheel trolleys, then tou can fit what you like.
  7. Nick Mitchener

    Dynamics Trolley wheels

    I think the problem is always the third wheel, getting replacement wheels is easy for the outer two but getting one that fits in the thirdwheel space was always the issue for me, as all three need to be the same diameter I drew a blank.
  8. Nick Mitchener

    Investigate thermistors

    The NTCs I had were around 23k ohm at room temp. However we only used them with DMMs set to measure resistance. I would question the need for 6V, if you use DMMs (Digital Multi Meters) you won't need to worry about the current being small.
  9. Nick Mitchener

    Tap!

    I'd call it a hose tail, or more correctly a male hose tail adaptor , though presumably they don't actually solve the problem, everybody gets soaked if you use one on a lab tap with a vent.
  10. Nick Mitchener

    Mammal Trap

    I see they do longworths with shrew holes now, we used to put catfood in to keep them alive!
  11. Nick Mitchener

    Big rainbow

    I used a slide projector and a spherical flask to make a single raindrop rainbow. I don't see why that would not work with an OHP. You need to collimate the light source, that's all.
  12. Nick Mitchener

    National Grid demo

    Obviously not because the technicians would step in to stop it.
  13. Nick Mitchener

    national grid simulator help please

    I think they are bulgin https://uk.rs-online.com/web/p/compact-power-connectors/0486319/
  14. Nick Mitchener

    national grid simulator help please

    I don't think those are audio plugs/sockets though.
  15. Nick Mitchener

    national grid simulator help please

    250V at 500mA is more than enough to kill.
  16. Nick Mitchener

    I'm thick at maths, plz help! :P

    When I look at a ratio like that I add the two together to find how many parts there are, so that makes 10 in this case. You know that the bit you know about is 9/10 and you want 1/10 for the other bit so that's why you divide the number you know by 9. It might be a simpler way of looking at it...
  17. Nick Mitchener

    Electron tubes

    I have the instructions for all the tubes on file including some ideas for experiments. If your EHT supplies have both 6.3V and 12V outputs start by filling the 12V with hot glue.
  18. Nick Mitchener

    mystery apparatus

    At the school I worked at till last week they no longer have them all hanging around as they were mine, now they are all here taking up space!
  19. Nick Mitchener

    mystery apparatus

    Yes Seebeck's that's the plate with holes though this one seems a combination with teeth on the outer edge like a savaerts. The frame with the handle is a whirling table, designed to stand vertically or horizontally as shown. (£2 and 2 shillings in 1924)
  20. Nick Mitchener

    mystery apparatus

    The multi tooth set is a savaerts wheel. Early form of sig gen, a strip held against it will produce a sound. A very large one was used to prove the existence of ultrasound. The one with holes is a siren. You need a glass tube with a narrow bent end, air passed through it goes through the holes...
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