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  1. kellys_eye

    Amp-hours, computer desktop power backup duration

    The battery alone won't work at all - I'm presuming (because you didn't mention) that the battery is to be used in a UPS device? I'm also presuming you're referring to a 12V battery? Such details are important! A 350W PC power supply consumes 1.5A @240V (3A @120V) therefore will consume 30A...
  2. kellys_eye

    Camera flash error code after repair

    That's not a standard value capacitor - the nearest 'normal' value would be 220μF. If you can't find the exact replacement then you need to find one that's as near as possible to the value (μF) and AT LEAST 315V (350V or 400V would be the next voltage rating) that can physically fit! Use the...
  3. kellys_eye

    Help with fence charger schematic

    If you can't be bothered with the math(s) - and I usually can't either - there are online calculators that do the dirty work for you. https://ncalculators.com/electronics/capacitor-charge-calculator.htm Fence energisers work by discharging a capacitor through a transformer to 'multiply' the...
  4. kellys_eye

    Camera flash error code after repair

    Yes. It's the capacitors ability to discharge the stored voltage that's important and a high internal resistance reduces that ability. The voltage will still be as high as expected though.
  5. kellys_eye

    Cooling electronic circut ?

    I'm trying to find the datasheet for the controlling device - it looks to be an MP3500DM (? confirm) - but there's scant detail around. Do you have a link to the original supplier? You can only determine the 'proper' use of the device from the manufacturers data.
  6. kellys_eye

    Camera flash error code after repair

    Test the capacitors ESR (Equivalent Series Resistance) - there are cheap meters that do this - to make a definitive check of its operation. The meter costs around $10-20 (Chinese retailers) but you may not want to go to this trouble and replacement of the capacitor itself may be just as quick/easy.
  7. kellys_eye

    Help with fence charger schematic

    It's related to the energy stored in the capacitor - check out this website for the details: http://www.johnhearfield.com/Physics/Capacitor_energy.htm from this you can determine that increasing the charge (V) on the capacitor or increasing the capacitance itself (C) can change the joules.
  8. kellys_eye

    Quickshifter

    Hmmm, thought I'd posted a reply..... seems like it got 'lost'??? (mods?) Repeated, below: You have it wired for 'low' and it should be wired for 'high'
  9. kellys_eye

    Measure temp, humidity, brightness

    There are, of course, other methods however you have to convert the sensor data to a form that you can manipulate for serial transmission. 'Raw' sensors will have an analogue output which will require conversion to a digital signal hence the recommendation for the already-converted signals...
  10. kellys_eye

    Measure temp, humidity, brightness

    Arduino, appropriate sensors based on I2C comms, software to collect and send via RS232 port or USB-enabled serial link.
  11. kellys_eye

    Sony CDP302 won't read a lot of discs.

    Could just be the laser has worn out - it happens. The more hi-quality units have replaceable laser mechanisms - have you tried to find out its part number and Googled for a replacement module?
  12. kellys_eye

    Not transistor and weak electromagnet

    I think the OP is referrring to the 12V supply to the solenoid and the voltage at the collector of the transistor when it is switched on - ideally it should be 0V to get the full supply across the solenoid but because the transistor isn't being driven hard enough (isn't the Arduino digital...
  13. kellys_eye

    Quickshifter

    You are referring to a situation known as 'rising edge trigger' and 'falling edge trigger' - it may sound self explanatory but I'll expand anyway. Monostable circuits are triggered by a pulse that can be obseved as a squarewave shape that has a leading edge and a trailing edge. Depending on...
  14. kellys_eye

    Not transistor and weak electromagnet

    The transistor is not being driven into full saturation but using a MOSFET would improve the situation dramatically. Use a logic-level MOSFET for best compatibility.
  15. kellys_eye

    Connection between a device and a LoRa

    Are you ok with the bit rate capability of the LoRa device?
  16. kellys_eye

    Sound Dynamics subwoofer schematics

    The marking on the pot..... Conventionally this would mean 1MΩ log law.
  17. kellys_eye

    Remote shotgun blast sound

    Can't see a speaker standing up to that kind of abuse for too long though. Torn cone surrounds....??? But, now you mention it, don't farmers have such stuff as crow deterrents?
  18. kellys_eye

    Solar astronomy taken to a new level for me

    Count me in as one of 'those that consider'..... I have faith in the regularity of solar events and historical records are enough evidence to confirm the effects - kind of peeing all over the cAGW crowd.... Fits with the many claims that there has been no warming since 2000. I stopped...
  19. kellys_eye

    (1973) Imperial HIFI 2700 stereo decoder and memories

    Gotcha... Sounds to me like that single resistor at the bottom of the preset bank has gone open circuit or poor solder joint....
  20. kellys_eye

    Help with Mic activity LED

    Connect the LED across the speaker (with a limiting resistor and reverse-connected diode across the LED). The LED will flash with the audio regardless of the speaker being connected/working.
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