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  1. duke37

    Identification

    If it is a triac, it must have adequate current and voltage characteristics. However, you will need to determine why it failed.
  2. duke37

    Identification

    It could be a TRIAC.
  3. duke37

    Building a Microphone should be easy, right?

    Wikipedia gives details of how a ribbon microphone is constructed. That would be quite a project.
  4. duke37

    I have the qualification electronics and i don't know it's occupation

    You could start by doing some woodwork which will teach you to do things carefully and not amputate your fingers. I spent some years running an electron microscope. This taught me that extreme cleanliness was essential and how to diagnose and repair electronic faults. A tip I give is not to test...
  5. duke37

    12v Automotive Cooling Fan Indicator Light

    Air conditioning in a 1966 MG Midget seems unlikely:) There is no information as to what is going on inside the control box to find out what is back feeding. Assuming the car has a 12V system, you could put a Zener diode in series with the led/resistor to drop 6V or so. Only when going fast...
  6. duke37

    12v Automotive Cooling Fan Indicator Light

    If the relay has two sets of contacts, use one for the fan and the other for the indicator. Alternatively, connect the led across the relay coil with a resistance.
  7. duke37

    Can anyone provide me a link or book how to make a woofer at home?

    I have an article by Peter Baxandall detailing how to measure speaker parameters such as cone mass and compliance. The speaker he evaluates comes out with an efficiency of 1.2%. * * Low cost hgh-quality loudspeaker. ....... Determining the electro-mechanical constants of the drive units. High...
  8. duke37

    Physical difference between low/high transformers?

    @cjdelphi If I upset you, I am sorry. This was not my intention, just that some typos are quite amusing. I produce lots of typos and try to correct them but one always seems to get away. I would disagree with Colin in one respect, The laminations are made as thin as is possible for assembly but...
  9. duke37

    Can anyone provide me a link or book how to make a woofer at home?

    The quoted impedance will always be higher than the resistance. Speakers are not ideal and the resistance can be substantial as you have shown. The resonant frequency and Q depends on the suspension which will depend on the cabinet. It would be interesting to see the measured impedance of the...
  10. duke37

    Physical difference between low/high transformers?

    I do not know the psychic difference between the transformers but here is a reading of my crystal ball. The frequency and voltage determines the flux which will be set by the numer of turns. The iron cores are split into laminations to reduce the eddy currents and the thinner the lamination...
  11. duke37

    Can anyone provide me a link or book how to make a woofer at home?

    A speaker is defined by its impedance which varies with the enclosure. The resisance as measured by an ordinary meter will be lower than this. Ideally it will be very low to get low dissipation and high power handling.
  12. duke37

    Help With Draining Batteries

    No pro here. Bulbs for a load would be the best since you do not have to supply a heat sink. A voltage reference and a comparator to turn off the load would be simple to implement. A timer connected across the load would give battery capacity. A switch would be needed, this could be done by...
  13. duke37

    help needed with electrical connection please

    In the colonies, they have an electricity supply of 120V-0-120V. Small appliancies connect to 0 (N) and one of the L connections. Larger appliances are connected between L1 and L2 to get 240V. Neither L1 or L2 are neutral, they have the same voltage but in antiphase. It looks as if the spa can...
  14. duke37

    Step Down DC Buck Capacitor Blow up

    Congratulations on your english. A led lighting up indicates the correct polarity. You may have had the polarity right but did you stuff 50V into the output?
  15. duke37

    (FAST) Finding the right power supply for an old boombox

    The AC power supply will not be 100% efficient so the radio is will use less than 28W. Also the batteries would not last long at 28W input. 12V regulated at 1.5 or 2A should be sufficient. Depends on how much sound you want out to annoy the neigbours.:)
  16. duke37

    Why would sections of an RGB LED string freeze animating after 30 mins?

    Possibly due to excess temperature.
  17. duke37

    Air actuated switches

    Yes, he is wanting to detect flow. Heated thermistors will change temperature and therefore resistance with flow. I used such a device to measure wind speeds on a vehicle close to the brakes. It became known as the bee catcher.:) Variation in ambient temperature may cause problems.
  18. duke37

    RF Field of PCB trace antenna

    Looks reasonable. You could try the program MMANA to model an antenna but I do not think the figures will be as pretty.
  19. duke37

    Improve smps

    Poor rat:) The SMPS rectifies the mains to produce DC for the switch mode to work. On switch on, there is a very large current until the capacitor is charged up. Sometimes a low value resistor is included to reduce this pulse but this wastes power and produces heat. Increasing the capacitor by...
  20. duke37

    Air actuated switches

    Consider a thermistor with a suitable circuit.
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