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  1. Alec_t

    Floating current source

    Agree with Gryd3. If the existing supply is isolated there's no point in adding opto-isolation.
  2. Alec_t

    Floating current source

    A current transformer won't work for DC currents. An opto solution would give a floating source if powered with a non-grounded battery.
  3. Alec_t

    What's wrong with circuit?

    Current through the 10uF cap?
  4. Alec_t

    Building a Microphone should be easy, right?

    That does not have the required contact positions if the PC has a 4-contact socket.
  5. Alec_t

    12v Automotive Cooling Fan Indicator Light

    You don't need a second relay. What has been suggested is that you connect the LED (which if rated for 12V already has a series current-limiting resistor) to the switched positive terminal of the coil of the relay which turns the fan on and off.
  6. Alec_t

    12v Automotive Cooling Fan Indicator Light

    Agreed. The simplest solution.
  7. Alec_t

    Capacitor explosion??

    Welcome to EP. When the pump was unplugged the start/run capacitor could have been left in a fully charged state and then discharged rapidly through the water. I'm surprised, though, that the water conductivity was high enough to allow sufficient current to cause an explosion.
  8. Alec_t

    Blown Canon LC-E6 charger for LP-E6 batteries

    The board around R1 doesn't look scorched, so it was presumably a short-duration overload which fried R1. I agree with Dave that the likely culprit is the switching transistor. It would also be worth checking what looks like a bridge rectifier, BD1, just above the circuit tracks with the...
  9. Alec_t

    Vibrating Butterflies how make them flutter?

    Be aware that these motors may not be intended for prolonged use, if they were originally designed for in-phone vibrators.
  10. Alec_t

    How to change LED flashing?

    .... and while you are re-programming it it woud be straightforward (to a programmer) to incorporate the fade-in fade-out feature.
  11. Alec_t

    Short Range Locator

    Welcome to EP. There are several ways to do this, but none would be easy or particularly cheap. E.g. 1) A matrix of pressure-sensitive pads/switches. 2) Scanned optical beams. 3) A grid of optical beams. 4) Scanning radar. 5) A camera and image-recognition software (arguably the...
  12. Alec_t

    Voltage regulators for magneto system mopeds

    Welcome to EP. Can you post a link to the magneto system circuit?
  13. Alec_t

    Solar powered plant waterer

    Welcome to EP. Couldn't you reverse that? Then you could omit the pump and use a solenoid valve instead. The power supply/control might be simpler.
  14. Alec_t

    Merry Christmas

    Happy Holidays!
  15. Alec_t

    Can anyone provide me a link or book how to make a woofer at home?

    Welcome to EP. I'm not aware that it's possible to buy a magnet of the right shape/polarisation, a voice coil and a cone separately, if that's your intention. I'd be interested to know the source if you have one. I doubt you'd be able to upgrade an existing 4 Ohm speaker to a 100W one, unless...
  16. Alec_t

    Motors

    ..... or if you want to shed a few calories after over-indulging at Christmas, how about making a pole lathe ? :D
  17. Alec_t

    AC Regulator for Bike Lamps

    That restricts the regulator to being a shunt one, with inevitable high heat dissipation (in the regulator and/or the coil). A series regulator could be more efficient, but would be more complex.
  18. Alec_t

    Auto switching polarity reversing switch

    Sounds like you're looking for an impulse relay, but they don't come cheap :( .
  19. Alec_t

    Resistor Value Identification Help

    Yellow, violet, green = "4, 7, 5" = 47x10^5 = 4.7MΩ.
  20. Alec_t

    Auto switching polarity reversing switch

    If you turn the power off, what is going to power the gadget that does the switch-reversal?
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