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  1. duke37

    Antique Automotive Resistors

    What does the kill switch do? does it short the ignition to earth. If so, I would look to see if the switch is working. Measure the voltage at both sides of the switch relative to chassis and again when the switch is 'tossed'.
  2. duke37

    Marx Generator

    If you are willing to use a higher voltage, then neon bulbs would make consistent spark gaps. They will fire at about 80V but will stand only a very low current. A Zener diode used to switch an SCR may do the job.
  3. duke37

    Power supply problem

    As you say, the power supply does not seem able to supply sufficient current. Give us the type numbers of the five devices attached to the heat sink. The current passes through these.
  4. duke37

    Critter Zapper

    I have managed to beat Steve on one occasion only, he is fast on the draw.:) I have repaired several fence energisers, the normal circuit is to charge a capacitor to 300V or so and then to discharge this through a 1:20 step up transformer. The high voltage is necessary to punch through furr and...
  5. duke37

    Woo-Woo Electrical R of a plant leaf vs. human thought

    I would not have thought that the specification of the stainless steel would be important. Stainless is used to reduce corrosion by the salt. There is plenty of stainless around, cutlery, razer blades etc. I have a stainless strip found on the road from some car bling.
  6. duke37

    Hall effect switching info needed

    My father's uncle had several patents dealing with caterpillar tracks. He did not have enough money to keep the patents active and never made anything out of it. I worked for an organisation which patented everything for a time but never made anything out of them so decided to publish instead to...
  7. duke37

    Hall effect switching info needed

    Electric motors have been optimised over many years, you are not likely to make anything more efficient. The magnetic gap can be very small, of the order of 1mm. It sounds as if your system uses pistons sliding in cylinders so you will have a large magnetic gap and large friction losses. I...
  8. duke37

    Finding Distance for Boundary btw cell towers.

    You have D4, does this mean D^4?
  9. duke37

    Hall effect switching info needed

    I have some electromechanical counters rated at 4V, they can stand 4V continuously. In order to get higher speed, I intend to run them on 12V pulses so they only pass current for some of the time and should not get hot, I will see if the maximum count speed will be much higher. The insulation...
  10. duke37

    Hall effect switching info needed

    The problem will be the inductance of the coil. You will need a short pulse which will need a high voltage to turn the coil on and a high voltage will be generated when turning the coil off. You will need to experiment with a short puse at say 100V and a fet which can stand 500V. The coil will...
  11. duke37

    What is this device

    That glass thing looks like a flash tube. They need a high voltage trigger close to the tube. What sort of electricity did you connect it to? Beware, they bite.
  12. duke37

    Question about radio waves and signal propagation

    At very low frequencies, the signals are attached to the ground and long and medium wave transmitters are placed where there is good ground to get good range, they go over hills. On short wave, say 2MHz up the signals tend to be more line of sight but there are ionised layers in the atmosphere...
  13. duke37

    Ignition coil driver.

    I do not know what you mean by a flyback core. Perhaps it is the core from a line output transformer. If so, it will be made from ferrite and suitable for high frequencies. You are then feeding into a car ignition coil which is relatively a low frequency device. The ignition coil has a laminated...
  14. duke37

    Ignition coil driver.

    You may be able to use it, you do not say what the output voltage is. A normal ignition system builds up a current when the points are closed and then when they open a large voltage is generated due to the inductive current. The voltage is defined by the capacitor across the points and is about...
  15. duke37

    Efficiency in DC motor

    Efficiency is power output/power input. At zero speed there is no power output so the efficiency is zero. Operating a motor outside its rating is not advised but this is always done on switch on when speed is zero or very low. The motor will not last long if held in this state. DC motors are...
  16. duke37

    Efficiency in DC motor

    The efficiency will be zero at zero speed and zero with no load. There will be a maximum with an intermediate load. Losses are due to windage and resistive losses. The optimum load will have the motor running close to its maximum speed so windage will not change much. I would think that...
  17. duke37

    Help with transformer for Lumenis Laser

    Is this a new transformer or one that has failed? Do the windings have connections as shown on the data sheet or are the colours wrong? Is the transformer energised properly? Put an iron screwdriver near the transformer. Does it vibrate?
  18. duke37

    Help with bridge rectifier

    I think that you have to look at the ground connections. If the current consumption of the +21V is higher than -21V then the votages will not stay similar. Give details of what windings are connected to ground. Are all windings floating?
  19. duke37

    Kenwood TS 830S

    How did you determine that the shorted turn is on the HV winding? Shorting to an adjacent turn will make very little difference to the winding resistance and all windings are inductively coupled so it is difficult to find the origin.
  20. duke37

    Replacement Motor - Sewing machine (Stepper or Servo?) More torque needed

    I wonder what the difference is between using AC and DC on a universal motor. I would think that the inductance would limit the current on AC and there would be no current limit on DC so, with no losses, the speed would go up to infinity:). A low voltage DC motor will have a strong correlation...
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