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  1. duke37

    advantage and disadvatnge of AC to DC converter circuit

    The input capacitor will define the input current. Use LTspice to determine this. The current is divided between the output and the zener diode. The output voltage will limited by the 9V zener and will drop if the output current demand is more than the input current. If you are going to isolate...
  2. duke37

    advantage and disadvatnge of AC to DC converter circuit

    1. It outputs 9V not ±9V so the 12V fan will run slow. 2. The output is not isolated so will give a shock if touched. 3. Very reliable high voltage components will be necessary. The input capacitor should be 1000V of the type which fails open circuit, not short circuit. 4. It is small, light and...
  3. duke37

    Resistor Question

    Except that K is degrees absolute and k is a thousand. These often get mixed up and m is used for a million when dealing with money.
  4. duke37

    Drive an heating element for an homemade oven.

    I have a 50 year old cooker with pancake rings which seem to bw happy running red hot. If you put another similar element in series, then the power will be 750W and this will be split into 375W per element. You could investigate what elements are used in commercial pizza ovens.
  5. duke37

    Drive an heating element for an homemade oven.

    The element is intended for use in a fan oven. If it is not cooled by air movement, then the element will overheat and nasty things can happen. Do you have a fan in your pizza oven?
  6. duke37

    Electric motor on planer quits running after 1 minute

    Get the motor rewound and save the planet.
  7. duke37

    Wire

    I sometimes use a folded piece of emery paper. Old wire can have the insulation removed with a candle flame. You can get solderable wire where the insulation is removed by the hot solder. This is almost mandatory with small diameter wires.
  8. duke37

    Question about a rectifier PCB of a welding power supply

    It seems to be a circuit to turn on the relay when the input voltage exceeds 300V. There is an electrolytic capacitor across the relay coil so it is DC and needs a DC supply via D5. Probably nothing to do with transient protection. Perhaps slow start.
  9. duke37

    Heathkit Condenser Checker

    I would go for all three of your suggestions. Removing the 1626 triode will give plenty of room for an auto transformer. The power will be fairly low as no heater power is required for the rectifier. Perhaps the triode was chosen to give low voltage drop, it being intended to be used for power...
  10. duke37

    Blow fuse

    A lamp limiter will let you get some voltage into the TV to do some investigation if the fuse is in the mains feed. Get a circuit diagram (top right) to help you on your way.
  11. duke37

    Solenoid constant power supply

    The final calc was wrong. The coil is 19mm i.d. 30mm o.d. Say 24mm average Number of tirns 46X4 Wire length = 46X4X24Xpi/1000 = 13.9 m. 18 awg has 20mΩ/m So the resistance is 0.28Ω, say a third. power = VxV/R or IxV or IxIxR 1V will give about 3A so power will be 3W not 10W as suggested...
  12. duke37

    Solenoid constant power supply

    If my calcs are correct, Diam about 24mm Wire length 13.9 m Resistance 20mohm/m = 0.28 ohm With a resistance of about a third of an ohm, I would think that 1V would be enough. This would give a dissipation of about 10W so would get quite warm.
  13. duke37

    Ignition Coil Driver Questions

    When Q1 turns off, a large voltage is generated on the drain and if the transformer is connected as shown, a much larger voltage is generated at the lower end, The upper end must be connected to earth , leave or short D2. D3 passes the positive pulse to the output. There is little disadvantage...
  14. duke37

    Ignition Coil Driver Questions

    D1 to D4 could be replaced by a single diode if it were connected the right way round. A faster diode than the 1N4007 would be advantageous, I suggest a UF4007.
  15. duke37

    Stuff I can get but should I?

    Speakers with transformers in them are intended to be used in 100V lines (UK). The transformer is tapped and can be used to set the volume at the appropriate position. A powerful ampllifier which can stand different load impedances is used.
  16. duke37

    Soldering iron wire

    I did not say what the OP should do. I said what I would do. I presume (s)he has read the other posts. The flex cannot be repaired but the damaged portion can be discarded. If the house fuse is the only protection, then the system is very dodgy. I use 1A fuses in the power plug for low power...
  17. duke37

    Soldering iron wire

    I would chop off the damaged section and connect the remaining piece if it is long enough. Make sure the connections are correct. The break is due to excess bending of the flex adjacent to the soldering iron. I often repair the cable to a smoothing iron which is moved backwards and forwards when...
  18. duke37

    Understanding the fundamental component of a wave

    There is a line 50Hz below 1200Hz and another 50Hz above 1200Hz and so ad infinitum. I think the modulation only has odd harmonics but I could be wrong.
  19. duke37

    Understanding the fundamental component of a wave

    It looks to me to be a 1200Hz carrier which is FM modulated with 50Hz. At a certain level of modulation, The carrier disappears.. The harmonics of the 50Hz are 1,2,4,5,
  20. duke37

    Ignition Coil Driver Questions

    I do not see how the 555 can be damaged from the fet but there is an input through the 56Ω resistor. A big fat capacitor across the supply may help.
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