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cliff park

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  1. Many people find the idea of using a multimeter quite daunting. But it shouldn't be really. Using it for the basics of DC voltage and Ohms should be very simple, and you can find out about other ranges as you grow in confidence. Plenty of people on here will help.
  2. It works just as well with contacts. It is the suppression of the arc that matters. The diodes can, of course, be fitted at the switch if that is more convenient.
  3. The standard arc reduction for this sort of situation is a diode wired in reverse across the solenoid coil, to catch the back emf induced by the collapsing field. The arc is when you take the probe off, or release the switch.
  4. Obviously your existing arrangement will only work with the track voltage one way round. If you want it to work either way round, and almost essential if you are thinking about stay-alive electrolytic capacitors, is to wire a small bridge rectifier, or four diodes in a bridge, after the pickups.
  5. I'm puzzled by the universal dislike of chocolate blocks, and the perceived problems. I have, I estimate, somewhere in the region of 400 screw connections in my house in mains sockets, lights, distribution boxes etc. If the screw terminal was such a problem why aren't these failing all the time, and should the electricity supply industry be using them?
  6. Try to imagine that each controller's output is floating. It is not tied to ground, or the mains or any other controller. The transformer ensures that. Connecting one leg of its output to another controller via the common rail just means the whole lot is floating. But if you have a common transformer winding then the controllers are connected in two places:- before the electronics and after. Effectively a short circuit. If that doesn't help please feel free to ignore.
  7. It is because they are bulbs. They get hot. LEDs run cold. Very often a bulb run at a lower voltage looks more authentically yellow than bright white. But if you run them at bright white they will get hot, it is the watts being dissipated. Nothing you can do will make them run bright and cold.
  8. I have followed this topic from the first post. I would like to make an observation. Not a criticism, I have no grounds to criticise. But sometimes I look at one of your pictures and I am there, in the station, in the farmyard, on the dockside. And then I look at another one , and it's a model railway. I have tried to analyse the difference, and I have come to the conclusion it's the camera angle. Low level pictures look real, high levels makes it a model. I guess it's because we see real scenes from ground level, and invariably we see models from a high angle, looking down. And the mind assoc
  9. Many years ago now I built some kit for audio use where the mixing took place a long way from the stage. Basically op-amps (running in something like an emitter-follower mode) reduced the impedance from the 50KΩ of the mics to a few hundred ohms, down a long cable, mixed at low impedance then back up another cable, converted back to high impedance to match the input of the amplifier. Now this was all analogue audio, and a long time ago but it seems to me that something similar is needed for the servos. Thinking about the original applications for most of these servos they are physically close
  10. There is a tendency to think that electronics is a precision discipline. It definitely is not. Resistor values is a case in point. You pick the nearest preferred value to the one you have calculated, and that probably has a 10% tolerance. (By the way if you buy a bag of 1000 1KΩ resistors at 10% tolerance NONE of them will be close to 1KΩ because they will have been removed and put in the 5% or 1% bags). A lot of it is trial and error, don't get too bogged down in detail. Experiment and you may burn an LED or two, but you will learn from experience, the best way.
  11. When measuring voltage you first set the range switch to an appropriate high range. Eg DC volts 200. Then place the probes across the circuit, ie one probe to each 'rail'. Then reduce the range until you have a sensible reading. Obviously most of the time you guess it's going to be say 12V so you set it to the next highest range, perhaps 20V or 25V. Much of this will be irrelevant if you have a self ranging meter. Measuring current is a whole different ball game. The meter has to be in series with the circuit. So disconnect a wire, connect one meter probe to the wire you just took off, and the
  12. Connect the battery to the terminals marked 'ac input', it doesn't matter which way round. You will have a very smooth output, no ac ripple, but it should work.
  13. Microswitches in particular are very robust and free from dirt problems as they are virtually sealed, and cheap
  14. The point is the RF suppressor is directly across the motor, which to all intents and purposes is a short circuit. It will never be subjected to the output of the high frequency cleaner. If the motor is connected to the rails then the cleaner will not be operating.
  15. As far as I can find 1976, which feels about right, quite recent.
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