Search results

  1. Hero999

    Design new 0 to 30V power supply.

    You're right, attachment edited. You mentioned simplifying the rectifier part of the supply; I don't think this is possible because two voltage doublers are required. I think it's probably best to just minimise the size of the capacitors. I don't see any point in going below 10μf, for the...
  2. Hero999

    Design new 0 to 30V power supply.

    Here's the latest .asc I've experimented with a current limit delay by increasing the value of C5 to 100nF. Connecting C5 to 0V just resulted in oscillation. The short circuit curve is not pretty, first there's a short transient spike caused by C7 and C5, then an exponential decay with some...
  3. Hero999

    Design new 0 to 30V power supply.

    The recovery from a short circuit at the higher voltage settings is slow and ugly because it takes awhile for the filter capacitor to charge when it's switched to the higher voltage. This is an inherent problem with reducing the input voltage at lower output voltages. I don't think it matters...
  4. Hero999

    Design new 0 to 30V power supply.

    I had a feeling you lot would jump on me for posting that circuit with a 9V zener. ;D That was never my intention, it was just a circuit I've already drawn. I'm using an ordinary silicon diode to provide a negative voltage of 0.7V. I might look into using a cheaper op-amp as there's no point...
  5. Hero999

    Design new 0 to 30V power supply.

    Seems overkill when all is needed is a couple of capacitors and diodes.
  6. Hero999

    patulong nmn po sa pagprogram ng pic 16f84.

    There's a Filipino forum similar to this one which people confused this place with. godspeeder18, This is an English speaking forum, try using an online translator if you don't speak English,, as mentioned above.
  7. Hero999

    Design new 0 to 30V power supply.

    You mean a negative supply? It's certainly doable, 0.6V will do but it's more components, at least the doubler capacitors can be smaller.
  8. Hero999

    Transistor base current

    A schematic would be nice.
  9. Hero999

    AC power outlet

    It depends on what you mean by a conventional power supply. I assume you're talking about an unregulated power supply consisting of a transformer rectifier and capacitor? If so you're right, a battery is better. But if you're talking about a regulated power supply i.e. one made with an LM317...
  10. Hero999

    Active filters

    Providing the schematic might help us answer your question.
  11. Hero999

    Amplifier feedback

    Sorry but I don't know what you're talking about. In future please provide as much information as you can when asking questions: preferably example schematics and a detailed description. Amplifier stability is mainly about gain and phase shift.
  12. Hero999

    Final stage amplifier

    It depends on the design. Lots of amplifiers use ICs for the output stage, TDA2003, TDA2050, TDA7294 etc.
  13. Hero999

    Design new 0 to 30V power supply.

    I agree, I would have hoped it would be lower but I looked at the datasheet and the worst case is 25mV, 10mV  is typical and 5mV typical with 600R resistor. It doesn't look right to me, the PDF you posted says the voltage before the MOSFET is 88.8V which is much too high. So you're having...
  14. Hero999

    Projects for a newbe

    I also use Crocodile Clips, Tina, Electronics Workbench. see the schematic attached (left to right). They might not be the best simulators, but they're good for schematics. Always use GIF or PNG for schematics, never JPG as it can be fuzzy especially after multiple saves. Reducing the colour...
  15. Hero999

    Design new 0 to 30V power supply.

    LTSpice is annoying me. I'm testing the stability of the over-current protection by connected it to a constant voltage linear ramp. The first thing I noticed is it was taking ages. I attributed this to it being unstable when the power supply voltage is really low. To get round this I set the...
  16. Hero999

    Voltage Controlled Switch

    In order to get someone to do it for you, you need a proper specification first. What are you going to be powering it from? A 5V regulated supply, a 12V bike electrical system? How much current does the relay need to switch? What is it switching? What value is the adjustable resistance? Or do...
  17. Hero999

    Design new 0 to 30V power supply.

    In theory that's fine. In practise, I'll always design the output voltage to be a little be higher than 30V because it's possible that component tolerances could limit the voltage to less than 30V. I could include a trimmer so the user could trim to exactly 30V but I don't see the point. I...
  18. Hero999

    Projects for a newbe

    I use LTSpice which is good because it has a simulator built-in. You need to have a few custom libraries before it's really useful as there are some components it doesn't have I disagree with audioguru, MS Paint isn't very good for schematics, there are much better programs. MS Paint is only...
  19. Hero999

    Voltage Controlled Switch

    I doubt you can buy the whole thing pre-made unless you're willing to pay someone lots of money to design it for you. Any relay can be connected to a comparator which will allow a variable resistor to be used to adjust the threshold; read the articles linked above.
  20. Hero999

    UPS

    No offence intended but I think you need to think more before asking questions. How much power can the normal mains supply? Does your adaptor get work out when you plug it in to the normal mains supply? How much power does a typical computer use? What difference could it possibly make? Why...
View older results
Top