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cliff park

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About cliff park

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    : Great Yarmouth
  1. Having a supply capable of supplying more than you need is never a problem. The unit will only draw what it needs and the power unit will be running at less than capacity, so will be happy
  2. Surely the simple way would be a relay, with changeover contacts such that when operated controller A is connected, when released controller B. Then each operator has a button. Operator in position A is a make button and operates the relay, which then holds over a spare contact. Operator's B has a break button which releases the relay. Another spare contact could be used to light appropriate LEDs.
  3. Slightly off topic. My Dad was a carpenter and was over the moon when PVA glue appeared on the scene, after a lifetime of preparing scotch glue. He used to dilute the PVA with water in a jamjar and one night he went to bed leaving a residue of diluted glue, and an old tablespoon in the jar on his sawbench. The next day he had to smash the jamjar to get the spoon out, then chisel the remains of the jar off his sawbench. The point is PVA is much more useful than you may realise, even diluted.
  4. Also what sort of level are your woodworking and electrical skills, and what access do you have to machinery , tools etc ?
  5. I recently bought Draper's temperature controlled iron and am very happy with that. I agree fully with junctionmad's comments as well.
  6. Fitting some LED interior building lighting I was looking for some very fine wire and remembered varnished wire. I am talking about the sort used in motors, solenoids, relays, even loudspeaker coils. The picture below is of the mechanism from an extension telephone bell. It looks like bare wire, but is of course varnished otherwise the turns would be short circuited. The varnish is actually the biggest problem. It is surprisingly difficult to remove. I use a small piece of fine sandpaper or emery cloth gripped between finger and thumb and drag the end of the wire through it. It must be removed before the wire can be soldered. The varnish does not take paint particularly well either. The picture below shows an LED powered by the two wires which are threaded through the eye of a needle (don't tell the wife I borrowed it). OK it is a darning needle, but still a small space. This wire, from the coil above measures 0.3 mm according to my vernier. In case you feel it can't take much current remember that motors, solenoids etc take quite a hefty current, and with only varnish for insulation there is no fear of it overheating. (Excuse the crude wiring, all done in a bit of a rush). So don't throw away your old solenoids, motors etc, strip them down and have a play.
  7. I think the mF on the diagram means μF, ie microfarad. So 4700μF would be correct
  8. The standard with fuses is that they blow at twice the rated current (don't ask me why) and will carry near to that value forever. They will get warm, maybe even hot, but not blow until twice the rated current. I have had plugs get hot, even good old MK, if the wires are loose or poorly terminated. eg only one or two of the cores actually terminated, or the screws not really tight. It does pay to go round your house about once a year and check all the screws and terminations where you can get to them , particularly those carrying heavy current like heaters, kettles, immersion heaters, washing machines, dishwashers, tumble driers etc. (And there will be an awful lot of them)
  9. Um......3 x 1.5 v is 4.5 volts. Why not solder 2 wires to the battery connections? Or make two dummy batteries, one for the first and one for the last, with a screw in the end of each and connect the wires to those. That way you can always revert to batteries easily.
  10. If the voltage is too high don't forget the simple option of half wave rectification. In other words one diode in series with one of the supply leads, and forget the bridge rectifier. It may work better with a bigger capacitor, depending on how much current the LED's draw.
  11. This is akin to a magician telling us how the trick was done and spoiling the illusion.
  12. One problem with all of these calculators is that they don't take account of 'preferred values'. In other words if the calculation says '395 Ω' then the modeller tries to buy one he will come unstuck. Always go up to the next preferred value, and if in doubt start high, if it's too dim come down. Unless you are feeding a lot, or they are very high powered, a ¼ watt should always be adequate. Several companies sell a selection pack fairly cheap, they always come in handy.
  13. In essence it is as you describe. And if it goes wrong it can cost several hundred pounds to put right, ask me how I know. They would not be feasable on solenoids anyway, and it is probably possible to adjust voltages on any other motors, including servos, to achieve a similar effect.
  14. Don't forget that asbestos is fine until you break it, saw it, drill it etc. The elements in these kinds of devices were usually ceramic, not asbestos. I know they look similar, butI have never seen an element with asbestos in it .
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