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  1. Alec_t

    Home circuit fault feeding back into speakers?

    Are you sure no current is being drawn from 'your' system by the occupier of an adjoining flat?
  2. Alec_t

    How to use LTspice

    I'm surprised the power diodes are that badly matched. 570 and 580 seem rather low and 832 seems high; I'd suggest replacing those. I've just checked a mixed bunch of power diodes in my spares box and they're all around 700.
  3. Alec_t

    I want to use a single power supply to operate two resistors alternately

    Try a standard Resistor-capacitor snubber.
  4. Alec_t

    How to use LTspice

    You should have nearer 22V DC if there's a reservoir cap. Those diodes look cooked. Have you tested them with your DMM's 'diode test' function? Have you reflowed the solder in case there's a dry joint?
  5. Alec_t

    I want to use a single power supply to operate two resistors alternately

    Interrupting a 10A coil current will result in a HUGE voltage spike, unless you include suppression components across the magnet coil.
  6. Alec_t

    Where can I find a timer circuit?

    Welcome to EP! Googling "off delay timer" or "time delay relay" will give you many choices.
  7. Alec_t

    Wanted: Electronics components

    If you're willing to use scavenged parts, then old TVs and Hi-Fis will have through-hole components with enough lead-length to be useful.
  8. Alec_t

    How to block Magnetic field coming from substation and underground power to property beside it

    Agreed. And if you use a mobile phone, how will you shield yourself from its much stronger field?
  9. Alec_t

    Electrical gauges

    Different driving techniques for moving coil and moving iron type meters might be required, as the latter usually need a good bit more current. (Amps rather than microamps).
  10. Alec_t

    How to block Magnetic field coming from substation and underground power to property beside it

    Why are you worried about 1mG (differential) when the Earth's field is ~ 500mG?
  11. Alec_t

    HP Printer doesn't work anymore

    Do you have a genuine HP cartridge?
  12. Alec_t

    Exercise Bike Computer doesn't work

    Welcome to EP! If it worked, what needs fixing? Just give it 5V again.
  13. Alec_t

    how PWM IC UC2843 works?

    Read the datasheet and any Application Notes you can find.
  14. Alec_t

    Boost converter

    As Bob said, the IRF520 needs about 10V Vgs to turn on fully.
  15. Alec_t

    How to use LTspice

    What goes into the 3 clips? Looks like a scorch mark on the pcb by the top clip.
  16. Alec_t

    Why are actuators inductive?

    Not all actuators are inductive. A brake slave cylinder, for example, is an actuator and is operated hydraulically. What do you understand by the term 'actuator'?
  17. Alec_t

    3-pin PC case fan -- power from alternative source?

    Perhaps the fan speed is set by a voltage (or average voltage, if PWM derived) on the third pin.
  18. Alec_t

    Grid Tie Inverters connecting 2x1000w

    Your grid energy supplier will need to authorise any grid connection, in the interests of safety. I suspect they will only allow the connection of approved gear.
  19. Alec_t

    How many red 5mm leds i can power with a 12 V 1.5 A AC-Adapter?

    This is how you could use the LEDs, arranged in strings of 5, each string having a resistor. Only 2 strings are shown here. With the resistor value shown, the LED current would be about 17mA per string, so you would be able to have 1.5A/17mA = 88 strings in theory. In practice, allowing for...
  20. Alec_t

    How many red 5mm leds i can power with a 12 V 1.5 A AC-Adapter?

    Welcome to EP! The number you can drive will depend on how much current each LED draws. Most LEDs like that will take 20mA ok, but you can choose a lower current and hence increase the number of LEDs used. Yes, you will need some resistors. Does your mains adapter provide a DC output or an AC...
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