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  1. duke37

    fluctuating magnetic field generator design

    I do not have the ability at present to show a schematic. Before a schematic can be developed, it is necessary to know the requirements. I suggest that you calculate the strength of the field and the area over which it is effective. Make a coil and measure resistance and inductance.
  2. duke37

    fluctuating magnetic field generator design

    Hope springs eternal:) Energy is needed to generate the field and this has to be dissipated to reduce the field. You will need to know the resistance and inductance and the frequency to be used. You will need a power supply, oscillator, switch (MOSFET), protection device (diode?). You might...
  3. duke37

    common mode choke

    You should be able to find the break in a fat wire like that and repair it. I do not see any signs of heating. Are the circuit board tracks continuous?
  4. duke37

    How an electromagnet can calculate kilogram

    According to Wikipedia the pound is a measure of mass which equal 0.453 592 37kg I got all tied up in school with trouble understanding the poundal:)
  5. duke37

    How an electromagnet can calculate kilogram

    No idea what a Kibble balance is , we used to kibble grain for animals to eat. The kilogram is a unit of mass, not weight so gravity does not enter into it.
  6. duke37

    what is the different between speaker wire and power wire

    As I said before, it will NOT be an alloy but just commercially pure. The only copper alloy used for wire that I know of is copper-beryllium (very nasty) which is used where strength is required. The wires do break if flexed too much and I often chop a piece off the end of the cable of portable...
  7. duke37

    what is the different between speaker wire and power wire

    Surely the other way round with the copper cladding the aluminium core. Never used it myself. With two metals, corrosion cann occur if moisture is present, try to keep to all copper. An alloy will not be used in a cable since alloys always have higher resistance than pure metals. Adding titanium...
  8. duke37

    Simple multitester

    You can use normal npn transistors if you put a diode (1N4148 etc) in series with each emitter. I would have thought that R5 would be better in the emitter of V3 to control its current.
  9. duke37

    Modifying a battery powered light to hardwired.

    Read #3
  10. duke37

    Modifying a battery powered light to hardwired.

    A wall wart is a lump which plugs into the mains and outputs a low voltage in its tail. Such a device is used in most low powered equipment as the equipment can be standard, only the wall wart needs to be changed for different power supplies. They give isolation - they will not give a shock on...
  11. duke37

    Modifying a battery powered light to hardwired.

    Welcome to the forum, you are doing right to start with low voltage, low power equipment. You can work up to lightning generators slowly.:) Look at the current demand of the light and select a fuse somewhat bigger than this. You probably need a 100mA one or so. A delay fuse that is one marked T...
  12. duke37

    Blowing fuses

    Valve amplifiers should never be run without a load. Semiconductor amplifiers should never be run with a short circuit load but should be OK with no load. To stop blowing fuses over and over again, then power up through a bulb (40W), this is known as a lamp limiter. This will limit the current...
  13. duke37

    How Is This RC Circuit Dropping Voltage

    There is no way of determining the input voltage, it could be 240V and 50Hz or something very different. The CR circuit will control the current (see #2) and the Zeners will clip the voltage to approximately +/-15V peak, passing excess current.
  14. duke37

    Trying to identify something that resembles a transformer!

    Lamp limiters as you propose are often used to start old valve radios and will limit the current. I have just used one to find out why a radio/ampmlifier was blowing fuses. It was a shorted diode in the diode bridge. I was very pleased at how easily the fault was found. The connections appear...
  15. duke37

    Newbie scope question

    Many measurements of high voltage ignition systems look at the voltage producing the spark but this voltage will only be present if there is no spark. A better mearurement would be the current which would be present during the spark. An isolating current transformer would protect the scope and...
  16. duke37

    Unresolved issue related to power-in

    A few more components in the Cockcroft-Walton multiplier will be smaller, lighter and more convenient than an external transformer.
  17. duke37

    Trying to identify something that resembles a transformer!

    The voltage depends on the number of turns. The resistance depends on the number of turns and the length of each turn. Outer turns are longer than inner turns. The label shows blue as 0V Brown is 50% up and red is 100% Blue to brown = 7.3 Brown to red by subtraction = 15.1-7.3 = 7.8 Not far...
  18. duke37

    HOW DO I SHIELD MYSELF FROM A NEIGHBOURS SMART METER?

    Look up "Faraday cage". You could line the party wall with aluminium foil but the longer wavelength radiation will get around the sides. Just live with it or find a submarine.:)
  19. duke37

    Casio Privia Px330 Piano Keyboard power adapter input

    The PSU is rated at 12V DC 1.5A with centre pin positive.
  20. duke37

    Flashing LED problem

    What is a Gainclone amplifier? Draw a circuit diagram of what you have and the specification of the capacitor. Is the power switch in the mains or low voltage supply?
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