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  1. Hero999

    Replacement for 2sk1058

    What are you using it for?
  2. Hero999

    Solenoid driver circuit

    How much current does the solenoid need? What's the current rating of the push button switch? You might be able to omit the MOSFET and drive the solenoid directly from the switch.
  3. Hero999

    Combining power supplies query....

    It depends on what power supply you want to use? The simplest way is to run the 3V device from 3.7V via a low drop out regulator or for greater efficiency use a switching regulator. Another way would be to use a boost converter to run the 3.6V device off 3V which would probably give the best...
  4. Hero999

    12v 3a Transformerless Power Supply

    No because it's not practical. Take a typical transformerless power supply circuit: For 3A@12V C1 would need to be 47uF.
  5. Hero999

    Stereo Power Supply Core Problem

    Are you sure you don't have a shorted turn? Did you touch the primary? You should leave it as is. Does it get hot off load? Measure the primary and secondary current. Is there DC in the secondary? You should always use a full wave rectifier with a transformer powering a high power circuit...
  6. Hero999

    help about parts

    I ahd a quick look for the bandpass filter in RS and Farnel without any luck. The other components shouldn't be hard to find or make.
  7. Hero999

    how do i fix laptop shorted adapters

    You generally don't bother, buy a new one. If you want to bother then check the main filter capacitor, then the switching transistors, followed by the rectifier on the output stage, then the bridge on the primary side.
  8. Hero999

    help about parts

    Don't create duplicate threads. Where do you live? It's impossible to help you without knowing the suppliers in your area.
  9. Hero999

    0-30V Stabilized Power Supply

    It's a matter of opinion. I like using a 10 turn pot so I can have course and fine control with one pot but having to turn it ten times to go from one end of the range to the other might annoy some people.
  10. Hero999

    lookin' 4 switch with reset

    There are plenty of ways to do this. It depends on what components you have access to? You can use the 555 timer, some inverting gates (NOT, NAND, NOR), CD4013, 74HC7474, a comparator/op-amp (LM311, LM393, uA741) a microcontroller or even a couple of transistors. Here's how to do it with a 555...
  11. Hero999

    Please help me to build-up this circuit

    Just use a mains transformer and relays. Using triacs means having ro use a transformerless power supply which isn't very safe because the whole circuit is at mains potential. With a transformer only the primary of the transformer, relay contacts, light and fan are at mains potential. If you...
  12. Hero999

    Push button start help

    ?
  13. Hero999

    Please help me to build-up this circuit

    I don't see any need for more diodes. It depends on what you want to do. I forgot to remove the 9V zener which is no longer needed.
  14. Hero999

    Please help me to build-up this circuit

    I told you before: you only need one relay to power the light, a total of two relays. Yes, a 9V 600mA transformer will do. The current consumption of the relays can be calculate using Ohm's law. There are many other redundant components in the circuit . I've removed them all. Here's the...
  15. Hero999

    Please help me to build-up this circuit

    The transformerless PSU won't be able to provide enough power to drive the relay coils. Why are you using two relays for the light? Yes, either  use a power transformer based PSU or replace the relays with TRIACs.
  16. Hero999

    Oscilloscope overshooting in RC high-pass filter

    Could yoube confusing  peak voltage and peak to peak voltage? If the V/division setting is 1V the signal should occupy two squares. You might also be using complementary outputs on the signal generrator (180 degree phase shift) so you'll see double the voltage, than you'd expect from the...
  17. Hero999

    DC-DC converter with limitations

    Why are you running a motor from a regulated power supply? An LM7805 will stop regulating (the output voltage will fall below 5V) when the input voltage falls below 7V and the battery will still have plenty of charge left in it. Why do you need a limting resistor? A resistor will slow the motor...
  18. Hero999

    Why diode voltage is 0.7V?

    Thye voltage is dependant on the temperature, current and materials. 0.7V wasn't chosen, it's due to the band gap of silicon. Germanium has a lower bandgap so the forward voltage is much lower 0.3V. Here's a link to an experiment you can do yourself...
  19. Hero999

    timer to trigger latch

    You're paying all that money for one good reason: safety. It's designed to be reliable so it doesn't fail exposing you to harmful cancer causing UV radiation. The product you've linked to seems like good value for money, it will be guaranteed to reliably and safely filter dangerous UV radiation.
  20. Hero999

    Switching Power Supply Repair Training

    Contact your local college. I'm not aware of any specific courses. The only real way to learn is to do an apprenticeship but doing a generic electronics course (A-level, HND, degree level) and some independent study will certainly help.
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