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  1. duke37

    DC step down

    With a wide range of input voltage, it is likely to be a switched mode supply. It should be possible to alter the feedback resistor to give 32V but it will not be possible to increase the current capability from 3A to 5A or the power from 144W to 160W.
  2. duke37

    12v Step-down?

    The 7809 or LM317 wil do about an amp and may need a heat sink. You can get switch mode buck convertors which are more efficient (less heat) and can provide higher currents. They may be a bit dirty and produce noise on radios.
  3. duke37

    Measurement device

    Do you need a measure of difference between two points or an accuracy of distance? To measure to an accuracy of 1/32 inch over 10 inch, then you will need an accuracy of about 1 part in 1000 which will be difficult to do with a potentiometer system.
  4. duke37

    Measurement device

    How does a digital caliper work?
  5. duke37

    Code Reader?

    There are computer programs to do this which can decode morse and other codings. I have not investigated them. I made a morse code reader many years ago using a Acorn Atom (6502), The more I sent to it, the more accurate it became.:) I am now using the G4FON Koch morse trainer to try to relearn...
  6. duke37

    What's this called (knob attachment)

    Let's have a cup of tea:)
  7. duke37

    Light chaser

    I think it would be easier to use 10 more leds each with a resistor and switch to your battery. You will not need more leds if you use steering diodes (two per led) Will the battery be able to supply the current for ten leds in parallel?
  8. duke37

    AC Adapter Help

    If it is AC, then polarity is irrelevent
  9. duke37

    AC Adapter Help

    What does that connector that you are holding plug into? What is the 'device'?
  10. duke37

    Sherwood AM-7040 No Left Channel

    You can connect in a different order with little loops of wire. Give details of the four types you have quoted. Voltage, current and pinout.
  11. duke37

    Sherwood AM-7040 No Left Channel

    Repeated fuze blowing will tell you nothing. Use a lamp limiter (a 40W bulb in series with the mains). so that a voltage can be applied without blowing the fuze. Compare the voltages on the good channel and bad channel. I would think that the output voltage should be near 0V, There may be an...
  12. duke37

    AC Adapter Help

    Show us a picture of the broken 'cord' and how it is terminated at each end.
  13. duke37

    Please help to buy those components

    Look at the circuit diagram, there are two coils so four ends. One coil will have many turns and is tuned by a variable capacitor. The other will have few turns and will be connected to the transistor, this one will be wound over the top of the other coil for close coupling. You can find which...
  14. duke37

    Please help to buy those components

    Ferrite rods are available from many hobby stores but cost a considerable amount. Get a long one for maximum sensitivity. As has been suggested, get one from a scrap AM radio which will have the coil already fitted. To wind your own coil, you ideally should use Litz wire with cotton (or other)...
  15. duke37

    Component

    That looks like a potentiometer with a plug at the end. What is it out of? You could check this with a DMM (meter).
  16. duke37

    AC Adapter Help

    It looks to me to be a plug/socket/voltage adaptor followed by a 230V to 24V transformer and a switch. I would get a US wall wart with 24V AC output and connect the output through the switch. What is it driving? Perhaps a 24V DC supply could be used which would give an extra option.
  17. duke37

    How do

    I'm old so, ey up me duck. Plenty of snow in Ilson today:).
  18. duke37

    Heating coils with a 9v, why doesn't this work?

    Maximum power output will be when the source resistance equals the load resistance. The heating in the battery and load will be the same. Treating a battery like this however will give a it very short life.
  19. duke37

    Transformer primaries in series, secondaries in parallel -- ok?

    There are transformers made which have identical primary and secondary pairs, these can then be connected in parallel or series as required. Two separate transformers could be near enough, it is easy to measure the differences.
  20. duke37

    Solar powered fan

    I do not know what you are trying to achieve. If it is to control temperature, then do this directly using a thermistor and a comparator.
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