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  1. Alec_t

    Looking for a 12v 3.5+A MOSFET

    73's, your link is just to the home page. Did you have a particular FET in mind?
  2. Alec_t

    How to improve upon this comparator driven LED circuit?

    Something like this, perhaps?
  3. Alec_t

    Can anyone help help me with a Gear Ratio?

    If you're talking tops, then the same amount of finger movement in a given time would make the 4mm diameter one rotate faster, but would require greater force to do so.
  4. Alec_t

    Ultrasonic sensor working underwater?

    What code? If it's something relating to measuring distance in air then you would need to reduce timing values to acount for the higher speed of sound in water. Of course, you might also need to adjust those values as a function of temperature, salinity etc.
  5. Alec_t

    Voltage multiplier

    100V and 50mA can be LETHAL, especially for anyone with a weak heart or pace-maker!! You should take great care when using this.
  6. Alec_t

    How to improve upon this comparator driven LED circuit?

    What is the buzzer voltage rating? Do you want LED1 to be on when LED2 is off, and vice versa?
  7. Alec_t

    n-mosfet replacement on Qnix lcd monitor

    The two pins at the 'back' are gate and source. The bigger tab is the drain. So all 3 are important! But the biggger tab also plays a big part in conducting heat away from the FET.
  8. Alec_t

    Class D amplifier - Power issue?

    How much space does this 'place' take up? If it's more than a cm or so of heavy conductor (not just a single veroboard track) it could be a problem.
  9. Alec_t

    Pocket Laptop (I'm new here...)

    Isn't it called a smartphone or a tablet?
  10. Alec_t

    Class D amplifier - Power issue?

    Are you using a star ground system, so that analogue ground, power ground left and power ground right are all brought together at a single point only? If not, the heavier current from using both speakers could be causing ground bounce and introducing undesirable feedback.
  11. Alec_t

    n-mosfet replacement on Qnix lcd monitor

    It looks well and truly cooked :(. Unfortunately the copper pad on the board is relied on for conducting heat away from the FET. If you can remove the green protective pcb coating in that region you may be able to attach a new pad to the board, made from a bit of thin copper sheet.
  12. Alec_t

    Class D amplifier - Power issue?

    I can't see anything on the battery label to indicate the battery output current capability. Where did you see the '1-2.4A output current' info? On the charger?
  13. Alec_t

    Can anyone help help me with a Gear Ratio?

    You seem to be talking about the circumferential linear speed, not the angular rotational speed. If you have two stepped/tapered shafts interacting (e.g. linked by a belt) as Minder says, then you can establish a 'gear ratio', like this.
  14. Alec_t

    Bicycle gadget

    Welcome to EP! Since this is your project, we don't do it for you but can give guidance. You are expected to show your efforts. What thoughts have you had so far?
  15. Alec_t

    Class D amplifier - Power issue?

    Battery labels are more likely to specify the Ampere-hour (Ah) capacity than the maximum current they can provide. Can you post a link to the battery spec?
  16. Alec_t

    Potentiometer as a Variable Resistor

    Yes, if it's dissipating several Watts without a heatsink or forced air cooling.
  17. Alec_t

    Need help with fet circuit

    AC or DC field? If AC, what frequency range?
  18. Alec_t

    PWM frequency and LC filter

    For your purpose the output PWM frequency = the triangular wave frequency = 2kHz.
  19. Alec_t

    Volts to ohms for fuel sender

    ??
  20. Alec_t

    Ultrasonic sensor working underwater?

    The link doesn't give enough info to judge. Looks like it's intended to operate just in air but be weather-resistant.
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