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  1. Alec_t

    Need help repair dead switching power supply

    It may be a trick of the light, but in that first pic in post #14 the two lower pins (i.e pins 1 and 2) of the NEC2501 (opto-isolator) look blackened. If so, check if there's a dead diode between those pins.
  2. Alec_t

    Is it possible to power relay and relay circuit with same battery?

    Since the Arduino can take 12V on its Power-in jack and has an internal 5V regulator, here's how I'd do it. M1 is a power MOSFET (logic-level type) to switch the solenoid directly (no relay used). D1 protects against the back-emf pulse when the solenoid switches off. D2, R1, C1 and C2 provide...
  3. Alec_t

    How to make a trap?

    How will you know when to spring the trap, if you're miles away?
  4. Alec_t

    Simple LED timer circuit

    Your standby current, plus average LED current over a year, is probably now less than the internal leakage current of your battery ;).
  5. Alec_t

    Why do I see random people on websites giving answers that make no sense?

    You need to follow the correct charging profile for lithium batteries or they can overheat, catch fire and explode! Check out www.batteryuniversity.com.
  6. Alec_t

    Simple LED timer circuit

    I'd go with the HEF40106 and wire all six inverters in parallel in dorke's circuit.
  7. Alec_t

    replacement 4 lead fan.

    Could the original 4-lead fan have a 2-phase or 3-phase BLDC motor? That would be expecting pulsed power, not steady DC.
  8. Alec_t

    DIY pyrography tool question.

    Success or otherwise would depend on the design of the wall-wart. Some may object to having their output effectively shorted and go into shut-down mode. Others may have no in-built current-limiting and so self-destruct in a spectacular fashion.
  9. Alec_t

    How to stop a motor from running when it is physically stopped

    Some form of brake will be necessary unless the motor is driving its load via a high-ratio reduction gearing which has lots of friction, e.g. a worm-drive.
  10. Alec_t

    Help powering Arduino!

    What is the Arduino being used for and what current draw would any attached devices have? Does the solenoid operate just once per day? A small 12V SLA battery would seem best for this use, but would then need a DC-DC converter to power the Arduino. Ideally a second DC-DC converter would enable...
  11. Alec_t

    Rechargable Batteries Remaining Life

    As pointed out on another forum, the number of possible charging cycles can not be known, even by the manufacturer.
  12. Alec_t

    Trying to design a system that provides 0v-4v voltage on one wire, and invers 4-0v on another.

    I agree with Bluejets. It just remains to choose the pot value. 5k perhaps?
  13. Alec_t

    Need to supress 0.5sec pulse for 0.5sec, then output

    Does the output signal have to last 0.5 secs too? What sort of signal (volts, current) is the Relay expecting?
  14. Alec_t

    footstep power generator

    There's also the small problem of energy conservation. The energy you (inefficiently) put into charging the battery has to come from the food you eat. So any saving on your electricity bill will be more than offset by an increase in your food bill ;).
  15. Alec_t

    How to convert frequency to light

    I suggest you research 1) RF amplifiers 2) Rectifiers,detectors 3) Voltage to current conversion
  16. Alec_t

    Need to supress 0.5sec pulse for 0.5sec, then output

    Welcome to EP! Why the negative sign? Are these signal levels normally high (+12V), going to 0V (or -12V) for 0..5 secs? Are these already-debounced signals, or are they from mechanical switch contacts (and so would need debouncing as a preliminary step)?
  17. Alec_t

    logic level FET

    How about this ?
  18. Alec_t

    LED FLASH/ON

    Here's one way, using a 555. The blue trace represents the LDR resistance (for kV read kΩ).
  19. Alec_t

    Heating elements for own built terranium

    A phase-controlled triac does not reduce the mains peak-to-peak voltage; it chops the mains voltage and so reduces the RMS voltage. Depending on your measuring equipment you may not have detected that.
  20. Alec_t

    Lock on posts

    You can't.Moderators control locks.
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