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  1. Alec_t

    How to control the speed of a 24vdc pump from circulating water temperature?

    Set the pot about half way to start with, then adjust it to get the outcome you want when the thermistor is at the required temperature. If no adjustment gives the right outcome then try swapping the pot and thermistor positions in the circuit.
  2. Alec_t

    Power Relay needed

    Why? That will require at least a precision voltage reference and a precision comparator. VDC would need to be extremely stable, so that LED current doesn't pull it down, otherwise the circuit would go into oscillation. What is your budget for this?
  3. Alec_t

    New toys today

    Very nice. What do they do?
  4. Alec_t

    Power Relay needed

    How much tolerance on the 1.5V? 10%? 1%? 0.001%? ...... What is the LED spec?
  5. Alec_t

    Power Relay needed

    Welcome to EP! Depending on the LED spec, it may be easier/cheaper to use a transistor instead of a relay to turn on the LED. How accurate does the '1.5V' really need to be? It would be very simple to use a transistor plus diode to have a 1.2V (approximately) threshold instead of 1.5V.
  6. Alec_t

    Repairing tumble dryer: what is this part?

    Looks like a thermal fuse. If you are getting ~ zero resistance continuity between all 3 wires then the device is probably ok. Is the pink wire thinner than the two black ones (if so perhaps it is used to sense fuse tripped)?
  7. Alec_t

    Simple Circuit Design Help

    This is a Homework problem, so what is your best effort so far at solving it?
  8. Alec_t

    Salvage haul - 7/11/16

    You've got enough nice bits there to build a ....... power supply :D.
  9. Alec_t

    Partially shaded solar panels

    You could get a fair amount of energy by burning them :D.
  10. Alec_t

    Pin 7 of 555 timer doesn't discharge

    I second the CD4060 approach. It could drive a logic-level power FET directly, but a buffer transistor would be needed for that IC to drive a relay.
  11. Alec_t

    Simple Motor Controller Circuit

    SMD types are very small.
  12. Alec_t

    How to control the speed of a 24vdc pump from circulating water temperature?

    It's probably not counter-intuitive to the Chinese manufacturer :D. Don't they read from right to left in China?
  13. Alec_t

    How to control the speed of a 24vdc pump from circulating water temperature?

    Do you mean the black wire now goes to ground and the red wire now goes to +5V?
  14. Alec_t

    Generating electricity from cell phone tower transmissions

    I'd be surprised if there were much energy to harvest or cause health problems if you're that close to the tower. The antennae are highly directional in the vertical plane, so you'd probably be in a radio 'shadow'.
  15. Alec_t

    doubts on projectors

    Welcome to EP! So, by 'projector' you mean simply a display?
  16. Alec_t

    How to detect very high frequency sound ?

    Acccording to this article you might be lucky using an electret mic up to ~50kHz.
  17. Alec_t

    How to slowdown capacitor discharge

    Google 'dynamo torch'. Those gadgets have been around for years. The dynamo charges a re-chargeable battery (which provides a more stable voltage than supercapacitors do).
  18. Alec_t

    How to slowdown capacitor discharge

    I'm not surprised if you apply 235V or more to a 2.5V motor :eek:. If you added resistance to the circuit to slow the discharge then much of the stored energy in the cap would be wasted as heat in the resistor. Your step-up circuit also wastes energy. It would be more efficient to run the motor...
  19. Alec_t

    How to slowdown capacitor discharge

    What is the rating (Volts, stall current) of the motor? 47uF doesn't hold enough charge to run a typical mains-rated motor for long, with or without a resistor.
  20. Alec_t

    Needing help with a 555 timer switch

    Here's how you could do it with a CD4013 or other dual D-flip-flop :-
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