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  1. Alec_t

    Help : PWM generation

    Welcome to EP! This circuit may meet your needs. Duty cycle is voltage-controlled but the frequency is controlled with a variable resistor.
  2. Alec_t

    I cant measure voltage on 100 picofarad capacitors on multimeter

    What about them? The resistance of any atmospheric moisture surrounding them immediately makes their high value rather pointless :).
  3. Alec_t

    I cant measure voltage on 100 picofarad capacitors on multimeter

    I doubt it. Do you know of a multimeter with a response time less than 2mS?
  4. Alec_t

    Need Help with simple 9V circuit design.

    It will take more than a pot for speed control. I suggest you google for some tutorials on 'PWM speed control'.
  5. Alec_t

    Trying to get laser sensor to activate jqc-3ff-s-z relay coil

    Try adding a pull-up resistor (e.g. 1k-10k) between +5V and the sensor output.
  6. Alec_t

    Sound waves travel

    Are you planning to annoy your neighbours? :eek:
  7. Alec_t

    Help current mode control and flipflops

    If you use a 3823 to generate the PWM signal and use that signal as the clock input to a flip-flop you can then use the complementary flip-flop outputs to do the logic Harald specified.
  8. Alec_t

    Help current mode control and flipflops

    Show us how you are driving your H-bridge. You would normally have one driving signal the inverse of another driving signal, but with a certain dead-time between them to prevent 'shoot-through'.
  9. Alec_t

    Help current mode control and flipflops

    The output duty cycle on either channel as shown is only half the input duty cycle. Is that what you intend?
  10. Alec_t

    DIY Hot Wire Foam Cutting Table (not working)

    If I'm reading your drawing correctly, your steel rod is a short-circuit across the heating wire.
  11. Alec_t

    Ultrasonic pest control

    There is also the possibility that the ultrasound could attract pests (e.g. if it mimicked the mating call of a mosquito or whatever :D).
  12. Alec_t

    source of replacement potentiometer

    If you intend to have only a 'set and forget' function you could just replace the pot with fixed resistors, or even by-pass the pot altogether.
  13. Alec_t

    Ultrasonic pest control

    I doubt you'd get whole house cover with a single transducer, as ultrasound is fairly directional and tends to be readily absorbed by furnishings.
  14. Alec_t

    Toggle between 2 LEDs on separate circuits in the same circuit?

    Perhaps the car's MCU which manages the fans detects the additions and refuses to power the fans?
  15. Alec_t

    replacing control panel on Treadmill with potentiometer

    Totally agree, but we don't know what is on the 'power board'.
  16. Alec_t

    replacing control panel on Treadmill with potentiometer

    How many wires go from the control panel to the power board? Any more than 3 and you'll need more than a pot for controlling the motor. Even with just 3 there's no guarantee a pot would suffice.
  17. Alec_t

    Monitor is damaged (not physically)

    Any chance you could have unknowingly contacted the screen with a mug, mouse, door key or belt buckle etc when moving near the screen? Do you have a cat or dog?
  18. Alec_t

    Monitor is damaged (not physically)

    That may well be the case, but I don't see how you can prove that to Asus. If damage of the type described, by over-insertion of screws, is even a theoretical possibility then it comes down to your version of events versus theirs. You can only hope that goodwill on their part will prevail. Might...
  19. Alec_t

    Need Help with simple 9V circuit design.

    Are you sure you have the LP2950 wired correctly? The middle pin should go to ground according to the datasheet. Your choice of colours for the wiring in your schematic is unfortunate in that it differs from convention so can lead to confusion..
  20. Alec_t

    Adding a trim pot to a fan motor

    A trim pot won't handle enough current for that task. You could try an incandescent bulb (not a LED or CFL bulb) in series with the high-speed winding. One of e.g. 60-100W rating might do.
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