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  1. Alec_t

    LTSpice installation under w10

    Probably a permissions issue. Did you run the installer with administrator privileges?
  2. Alec_t

    Wattage on things

    Is 1000W the power consumed at normal running speed? Peak power needed at motor start-up could be much higher.
  3. Alec_t

    Will this be safe to test? Homemade Laptop Power bank

    So, the Mac needs >4.3A. The DC converter in the link is rated for 2.5A output only :( . The converter would have to boost 5V to 20V (the charger output voltage), so even if it were 100% efficient it would draw at least 4.3A x 20V/5V = 17.2A. That seems beyond the capability of your powerbank.
  4. Alec_t

    About the illegality of posting an essay for translation base reference

    Weren't you happy with the answers you (Karkas) had over at ETO?
  5. Alec_t

    Problems with RGB & LED tape light w/ Power supply - Buzzing/Pulsing

    Triac-based dimmers cause current pulses which, in turn, can cause transformer core laminations to buzz if they aren't adequately clamped or bonded together. Your driver includes a transformer.
  6. Alec_t

    Will this be safe to test? Homemade Laptop Power bank

    Welcome to EP! What is the peak current demand of the Macbook? What input voltage does the Macbook require? What is the voltage output of your powerbank? Will your Macbook recognise a non-Mac power supply?
  7. Alec_t

    Current variations.

    It can only do both simultaneously for one specific constant load resistance. A battery on charge is not a constant load, so a charger will usually provide a constant voltage or a constant current, depending on the required battery charging profile.
  8. Alec_t

    Need to reduce 5V 500ma to 3V 30ma

    The AAA battery has a quoted capacity of ~ 1000mAh, so if your keyboard is draining it completely in 3 hours it must be drawing over 300mA !! Conclusion: the keyboard is faulty.
  9. Alec_t

    741 op amp dilemma

    You appear to have the inverting and non-inverting inputs swapped. R6 as shown would provide positive feedback. You want negative feedback for an audio amp. R1 and R2 values are rather low, so the battery life will be short. The 741 is bad because (a) it is noisy and (b) it can handle inputs...
  10. Alec_t

    Relay with RTC control

    Something here suitable?
  11. Alec_t

    741 op amp dilemma

    Partly due to the 741 being an awful opamp (by today's standards) :) . Post a schematic of your amp so that we can spot any likely cause for your woes.
  12. Alec_t

    I need to power a synthesizer with a battery...Please Help :)

    Nice. Macgyvr would be proud!
  13. Alec_t

    How to calculate motor maximum acceleration with load

    Looks correct to me, providing the rated maximum torque occurs at start-up with the motor stalled.
  14. Alec_t

    Is this an inductor?

    If by that you mean the meter showed open circuit then the component is most likely a 39nF capacitor.
  15. Alec_t

    Help with sensing a stopped sprocket

    Isle of Wight :) . A relative of mine used to live there and occasionally received mail which was posted in the UK but was redirected from IOWa (your neck of the woods!) .
  16. Alec_t

    Electromagnet V vs Amp vs Turns?

    ..... but if the electromagnet space is restricted, then using thicker wire means you can fit fewer turns into that space, so you need to increase the current to maintain the field strength.
  17. Alec_t

    Need temperature sensor

    What do you mean?
  18. Alec_t

    Temperature In Household Electrical Line

    It shouldn't be more than a few degrees above ambient room temperature, but depends how much current you are drawing from the power point, and whether or not the power point wiring complies with the local code regarding wire gauge.
  19. Alec_t

    Subwoofer Amp blowing fuses

    I'd check for shorts on the varistors (those blue discs in the power supply section), the bridge rectifier and any fat semiconductors. Ideally they should be checked out of circuit, but a dead short should show up even in circuit (though might be confused with a very low impedance in parallel...
  20. Alec_t

    How can I swap a stock piezo buzzer for a louder 140db buzzer?

    Interesting that two of the battery cells face one way and the third faces the opposite way. That's an accident waiting to happen :eek:.
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