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  1. Alec_t

    How To Prevent Short Circuit With A Simple Wire From One Outlet Prong To The Other

    A resistor having any finite resistance will prevent a short circuit which, by definition, has ~zero resistance. What you are looking for, I think, is a current limiter.
  2. Alec_t

    How To Prevent Short Circuit With A Simple Wire From One Outlet Prong To The Other

    A resistor would be one possibility. Or a lamp, or a motor, or ....... But mains voltage can KILL you. If you have to ask such a question you should NOT be messing with mains sockets.
  3. Alec_t

    New Product Prototype

    What type of charging socket are you using? It may be possible to rig something so that a dummy charging plug would switch the receiver off. A switched 3.5mm jack could do this, as used on some mains/battery portable radios.
  4. Alec_t

    Failure on oven control board

    Looks to me (looks can be deceptive) as though the cause could simply have been a bad (loose, poorly crimped?) connection from the red wire to the push-on spade connector inside the blue housing. High current through that relatively high resistance would have resulted in localised over-heating...
  5. Alec_t

    Identify an AC/DC Adaptor

    Looks like a 2-pin DIN socket to fit one of these plugs.
  6. Alec_t

    Please Help Me Assemble 10m Remote Ultrasonic Compact Circuit

    If this is for an alert, surely a loud audio-frequency signal is needed. Why ultrasonic? What transducer do you have available and what is its specification?
  7. Alec_t

    Curtis TV

    Only 50 hours. Is it still under warranty?
  8. Alec_t

    Unidentifiable radio interference on vintage audio (listen!)

    Do any of your neighbours have a cannabis farm, requiring high-power grow lights, powered by switch-mode supplies? :) :)
  9. Alec_t

    Power Supply for Mr Christmas Santas Marching Band - uk

    Is it possible the input was AC, from a centre-tapped transformer secondary; or two different voltages? Is the switch just a simple on/off one, or does it have some selector function?
  10. Alec_t

    4098 Rising and Falling edge detection

    What is the approximate supply voltage rise time at power-on? An R and a C with a time constant greater than that can be added across the supply (R to +, C to ground) with the reset pin connected to the R/C junction.
  11. Alec_t

    Help with Pot and LM3914

    You may need to use a signal peak detector to make the display more visible. See Fig 17 of the LM3915 datasheet.
  12. Alec_t

    Model Ship LED Project

    It's ok to connect the three non-flashing LEDs in series, with one current-limiting resistor, but I wonder if each flashing LED should have its own resistor and be individually connected to the 12V (or 5V) supply? The reason is that one turning off would turn off the other two if connected in...
  13. Alec_t

    Car phone charger with AD85063D. Does it deliver?

    Some phones recognise a 'genuine' charger by sensing certain voltages on the USB data pins. If those voltages are 'wrong' the phone may not accept a high charge rate.
  14. Alec_t

    What's wrong with circuit?

    Right. The voltage across the 220u cap (the 'supply' voltage for the transistor) is about 16V. The pull-down resistors on the transistor base keep it permanently switched on, drawing about 5mA collector current. Triac gate current (about 8mA according to LTspice) flows via the 390R resistor and...
  15. Alec_t

    Happy New Year!

    ... and from me.
  16. Alec_t

    DC magnetic circuit

    Since this is Homework Help, not "Homework Done for You", please post your best effort so far at a solution based on your class-work.
  17. Alec_t

    need help repairing a power inverter

    .... and the photos should be close-up, well-lit and focussed so that component markings can be read easily.
  18. Alec_t

    Floating current source

    Does that comma denote a decimal point?
  19. Alec_t

    Floating current source

    How accurate do you need the current control to be? The current transfer ratio of an opto-isolator is quite temperature dependent (e.g it could vary by ~10% over a 40C temperature range).
  20. Alec_t

    Charging 2x NiMH 9v batteries in series

    Can't you charge them separately? Whether or not a 9V charger could be modified would depend on the charger construction.
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