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  1. Alec_t

    efficient batteries.. help!

    Welcome to EP, Tom! You do realise an entire battery-building industry has been attempting that task for decades? We can't design the battery for you, or do the years of research necessary. Come back here if you have a specific question we can help with. Best of luck.
  2. Alec_t

    12V adapter + resistor = 9V adapter?

    So he is. :oops:
  3. Alec_t

    Electromagnetic Fields

    Wikipedia will have the answers.
  4. Alec_t

    12V adapter + resistor = 9V adapter?

    Be aware that the LM7809 has a quiescent current as high as 8mA (the 78L09 is lightly better at 6mA), so your pedal would need an on/off switch to avoid running the battery flat quickly. It's possible that your pedal would work ok from 12V directly, but without a schematic we can't be sure.
  5. Alec_t

    12V adapter + resistor = 9V adapter?

    I can't believe a flange pedal designed to run from a 9V battery (presumably a PP3 size) would draw more than a few mA. Therefore a zener-based regulator would probably suffice. A 7809 looks like overkill. Do you have a schematic for the pedal?
  6. Alec_t

    Switching power supply

    I agree with duke37. The internal components are unlikely to be rated for 36A. In particular, the inductor may saturate if the current is greater than 30A. That could lead to catastrophic failure of the supply.
  7. Alec_t

    JBL Home subwoofer ES150P/230 buzz noise

    Welcome to EP! That's one sad-looking dead electrolytic capacitor. It's neighbour doesn't look to happy either. With a bit of luck and a following wind, just replacing the caps will solve the problem; but the chances are that its/their failure will have caused collateral damage to other components.
  8. Alec_t

    How single phase meter work

    The meter uses a microprocessor.
  9. Alec_t

    Arduino Air flow meter (low speeds)

    Unfortunately fuse wire has a very low coefficient of resistance change with temperature. Instead of a hot wire I wonder if a tiny bead thermistor, having a much greater coefficient, would do the job? Since the air flow would be reasonably constant the thermal mass of the thermistor, even if...
  10. Alec_t

    Circuit Help :) - LDR LED Cube (Urgent)

    Also consider whether you have the pot wired correctly and what are the consequences if it gets twiddled to either extreme position. And welcome to EP!
  11. Alec_t

    Arduino Air flow meter (low speeds)

    A hot wire type mass air flow (MAF) sensor may meet your needs.
  12. Alec_t

    DC motor design

    Which mechanical part?
  13. Alec_t

    Low power inverter circuit

    I would guess your transistors, or the 555, can't handle the current demand of the transformer primary. Is that a hand-wound transformer? How many turns on the primary and secondary?
  14. Alec_t

    Music Keyboard - Increase Sustain/Decay Time

    I doubt you'll be able to modify the piano the way you want, unless it's a prehistoric one with analogue circuitry defining the ADSR envelope. Most instruments these days do things digitally, so any mod would require software changes.
  15. Alec_t

    Connector for satellite docking mechanism

    I second the magnetic connector. Something like the Apple Magsafe.
  16. Alec_t

    Help needed on simple short circuit protection

    That's not what your diagram shows :confused:.
  17. Alec_t

    Does electron die?

    Generating electricity doesn't actually create electrons; it just causes existing electrons in conductors to move around a circuit.
  18. Alec_t

    How to read and solve passage?

    Look at and listen to, for example, the BBC's World Service.
  19. Alec_t

    How to read and solve passage?

    Consult Wikipedia?
  20. Alec_t

    How to delay the relay

    Here's one option: (Not shown are the 9V supply regulator, transient suppression components and supply decoupling arrangement).
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