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  1. Alec_t

    I want to connect a water sensor to a speaker

    Welcome to EP! A length of screened cable would do the job.
  2. Alec_t

    Replacement Motor - Sewing machine (Stepper or Servo?) More torque needed

    Personally I'd go for a DC motor with PWM speed control. PWM has the advantage that torque is fairly constant over a wide speed range.
  3. Alec_t

    Headset music volume dimmer

    It would probably be easier circuit-wise to switch the music off entirely rather than reduce the volume.
  4. Alec_t

    Tank water level sensor.

    .... and the reed switch method that Minder suggested can easily be extended to have several reed switches at different depths.
  5. Alec_t

    Activating a pump based on water flow

    You could try a standard 'power-on reset' arrangement. Connect pin 4 of the 555 via a high value resistor to the +ve rail and via a fat cap to ground.
  6. Alec_t

    I'm trying to create a energy grid monitoring system using Arduino

    I think you're right; but whether or not the utility will do anything to overcome public protest is unknown :).
  7. Alec_t

    Measuring an IC's input resistance

    Anything from 1V to 10.5V is allowable.
  8. Alec_t

    LED or CFL flickering with motion sensor in circuit

    Not everyone. Re-read post #8.
  9. Alec_t

    I'm trying to create a energy grid monitoring system using Arduino

    Welcome to EP! You could use a transformer with a low voltage secondary, e.g. 3VRMS, to monitor the mains presence/absence/voltage/frequency. Even if you do monitor the mains, is the power company likely to accept your readings?
  10. Alec_t

    Broken server RAM gold plating

    Looks like severe over-heating caused failure of the bond of the pcb track to the substrate. Not surprising if you're hot-plugging/unplugging the RAM!! What a mess.
  11. Alec_t

    Sort of baffling what happened after a thunderstorm

    Welcome to EP! My guess is the night light switch desn't always make a good connection. Btw, doesn't your keyboard have a "." character? Your post is very difficult to read with no sentence breaks.
  12. Alec_t

    Immersion water heater in a metal cup

    Not to me. No earth and not double-insulated.
  13. Alec_t

    How do I replace this pot with 2 knob pots, coarse fine.

    Either would work, but would determine the direction of adjustment needed for increase/decrease.
  14. Alec_t

    How do I replace this pot with 2 knob pots, coarse fine.

    Yes, a 1 megOhm resistor and a 1 megOhm pot. I think you've already tried the option below and found it didn't work?
  15. Alec_t

    How do I replace this pot with 2 knob pots, coarse fine.

    You could try this :
  16. Alec_t

    How could I convert/boost PWM frequency? 500Hz to 25kHz?

    Can you post a link to the fan datasheet?
  17. Alec_t

    Beginner needing help - Simple timer circuit for reversing 5v motor

    Yes, IMO.
  18. Alec_t

    Beginner needing help - Simple timer circuit for reversing 5v motor

    Agreed, but during that brief period (~1uS in simulation) the supply is effectively shorted. While that may not harm the FETs it may upset some other part of the circuit.
  19. Alec_t

    Beginner needing help - Simple timer circuit for reversing 5v motor

    Consider T3, T5. With a 5V supply, both will need to have a Vgs(th) of magnitude a good bit less than 5V to ensure full turn-on. There will therefore be a common gate voltage at which both FETs will conduct at the same time.
  20. Alec_t

    Beginner needing help - Simple timer circuit for reversing 5v motor

    With the circuit shown there will be a high shoot-through current.
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