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  1. duke37

    Battery charger Diode question

    If bolting direct to the plate, then the diodes will need the correct polarity. I would have expected three diodes to be connected to one plate and three of opposite polarity to be connected to another plate with the output from the plates
  2. duke37

    Mobile linear amplifier

    Run it for a few seconds then use a digital temperature detector (finger). I suspect than the PSU cannot supply the voltage at 55A so the heating may be low.
  3. duke37

    Something small and loud needed.

    Get a ferret transmitter.:) I have made an oscillator using a 4093 in a 35mm film container. This is not waterproof.. I have connected it to an underground cable and followed it with a medium wave radio.
  4. duke37

    High voltage air cored transformer

    You will need a core to keep the primary energising current under control unless running at very high frequency. I would suggest you look at the construction of TV line output transformers which use a hjgh frequency, ferrite core and many turns. Note that in this case the volts/turn can be...
  5. duke37

    DC power over coax

    I have repaired a few electric fencers which have been damaged by lightening. They only have one wire running into them. Of course a loop could be worse.
  6. duke37

    Running house LED lights on AC

    If you wish to improve efficiency, get rid of light shades.
  7. duke37

    Transformer primaries 90 degree phase difference

    Putting rectified AC through an inductance gives a steadily increasing current. If the resistance is zero, the current will rise to infinity. Not likely to be obtained in practice. With a large inductance such as a motor, the pulses will be smoothed to give an almost constant current. An AC...
  8. duke37

    Transformer primaries 90 degree phase difference

    The bridge rectifier will put DC through L1 which will saturate and burn out. C1 will charge up and stop current passing through L2. You will not get 90 degrees offset, you may be able to approach it with certain capacitor values and loads. Have you tried a simulation?
  9. duke37

    Running house LED lights on AC

    If you use two LEDs in inverse parallel on AC then they can be overrun a little since they will be resting for half the time. Where do you get a 6V LED? A current controlled supply can be quite efficient and more efficient than a resistive dropper.
  10. duke37

    How to wire tweeter to speaker

    Please define what you mean by speaker. You have a stereo system with one amplifier driving left and the other driving right. The tweeters are normally connected to the amplifier through a capacitor. These will not be in the pf range, such values will be used for radio frequencies.
  11. duke37

    Variable time on/off switch circuit, for model tree-house project

    If the leds are run at their maximum permitted current, it may be adequent to pulse them on for 50% of the time thus doubling the lifr of the battery.
  12. duke37

    FM & LED shop lights

    So, how was this miraicle achieved?
  13. duke37

    Use Xbox one X (US) in Europe (Voltage converter)

    A transformer can change 240V to 120V but will not be able to change 50Hz to 60Hz. This may not matter, it depends on the type of power supply the Xbox uses. Remember that plugs and sockets differ between european countries and also Canada. 1kW should be enough, it will be a big, heavy lump...
  14. duke37

    Rutland ESB57 Energiser low voltage help!

    Good quality capacitors can be obtained from RS comonents or Farnel. The 3.3μF capacitor has a hard time and there are special expensive capacitors available used in Gallagher fencers Edit: RS components Vishay polypropylene 600V 3.3μF, £6.16
  15. duke37

    Rutland ESB57 Energiser low voltage help!

    I would check the voltage on the 3.3μF capacitor. I expect it should be about 400V. Do not kill yourself:). There is another component nearby with a yellowish patch, possibly just a trick of the light. The next thing to check is the EHT tranformer, this may be the transformer with the twin...
  16. duke37

    Help with an inductive heating circuit!

    You have some funny units, perhaps you mean 140kHz, not 140KHz. Please post the latest circuit. Do both fets contribute to the output? A thermocouple or a varistor could detect the temperature. You will need a matching circuit to stop the oscillator, how this is done depends on the specific...
  17. duke37

    Crystal sets - How do they work? :) (with real diodes)

    The 0.3V for a germanium diode to conduct is only a rough approximation. I am sure someone can come up with the logarithmic equation for a more accurate result. Capacitors should have very low loss and the circuit Q will depend on the coil. Do not get mixed up between circuit Q and loaded Q. To...
  18. duke37

    Basic understanding of low pass filter

    The circuit you show is a potential divider. If a divider is made from two resistors, the value of the resistors will determine the output voltage. If the 'bottom' resistor is replaced by a capacitor , then the impedance drops as the frequency rises so the voltage drops. There is significant...
  19. duke37

    Graph the output waveform of a MOSFET circuit

    So am I :) But I am too old to learn now.:confused: To get the output you want, Q1 should be changed to a resistor or constant current source. In any case to simulate the circuit you will need voltage input and fet characteristics, neither of which are specified.
  20. duke37

    Graph the output waveform of a MOSFET circuit

    What is the circuit intended to do? What voltage is needed to turn Q1 and Q2 on. A normal fet will turn on with 12V or so on the gate. Assuming Q1 is on, this puts 12V on the gate of Q2, turning that on also. The voltage supply is shorted. Turning off Q1 will allow Q2 to turn off giving an...
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