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  1. Alec_t

    Time reversal transformation

    An xxxxxxxxxxxx is one option. Is this homework?
  2. Alec_t

    Single pulse output

    Here you go :
  3. Alec_t

    400ma bipolar 12v 2 ohm drain

    You will need to make sure that back emf doesn't fry the computer if you start substituting inductors.
  4. Alec_t

    400ma bipolar 12v 2 ohm drain

    Do you know how the computer does its 2Ω check and its 400mA check? I think you would have to simulate those operations correctly, particulaly any voltage switching and timing constraints, to fool it into believing the stepper was attached. Assuming your stepper has multiple coils, does the...
  5. Alec_t

    400ma bipolar 12v 2 ohm drain

    In that case the 2Ω is irrelevant; a 400mA current source would suffice. How long does the start-up check take?
  6. Alec_t

    400ma bipolar 12v 2 ohm drain

    A stepper motor isn't a simple 2Ω resistor, even if that is its DC coil resistance. The coil has inductance which causes coil current to build up over time. I doubt the PCM will be fooled by a simple 400mA or 2Ω load (I could be wrong). Won't disconnecting the stepper have an adverse effect on...
  7. Alec_t

    Op Amp with a/c output

    The input voltage changes the base current of the transistor, which causes a bigger change in the collector current (that's the way transistors work) and hence a big change in the collector voltage. The output voltage change is bigger than the input voltage change and the power out (voltage...
  8. Alec_t

    Testing a diode with a 9V battery tester

    Because some diodes obviously have a Vf less than 9V.
  9. Alec_t

    Testing a diode with a 9V battery tester

    A 9V battery may not provide a high enough voltage to test all microwave oven diodes. The NTE517 diode, for example, has a rated Vf of as much as 14V, so would not conduct appreciably with only 9V applied.
  10. Alec_t

    As cheap as PWM duty sweep

    Thanks for the feedback. It's always good to know how close reality is to a simulation.
  11. Alec_t

    Magneto kill terminal...

    On simple magneto-generators, as used e.g. on motorbikes, I think the kill switch merely short-circuits the (low voltage) generator coil that powers the ignition circuit.
  12. Alec_t

    As cheap as PWM duty sweep

    If you want cheap ....... Only 2 of the 6 gates in the IC are used. 0% to 100% duty cycle sweep. R1,C1 set the sweep period. R3,R4 set the sweep amount. R5,C2 set the basic PWM frequency. Note: the frequency varies by a 2:1 factor over the sweep period, but this is immaterial for the fan control.
  13. Alec_t

    As cheap as PWM duty sweep

    Welcome to EP! Is this a school/college project? What pulse frequency? What will control the PWM? Potentiometer? Voltage? ...... ?
  14. Alec_t

    Solenoid Piston help

    Which way are your magnets polarised? Across a diameter, or orthogonal to the major faces? From your sketch it looks as though you are assuming the latter.
  15. Alec_t

    3D printer for replacement plastic parts?

    Don't use PLA filament if you want the printed article to withsatand heat or the environment. It has a low melting point and is bio-degradable.
  16. Alec_t

    Please can I have some help with a boost/buck convertor?

    It's possible that the inductance of lengthy wires to the pots is causing circuit instability/oscillation and consequent overheating of components.
  17. Alec_t

    Does someone here know what data a Chromecast delivers to the internet?

    Have you searched for "chromecast privacy policy"?
  18. Alec_t

    Post-soldering August ep 650 headphones, bluetooth mode doesn't turn on. Any hope?

    Don't try puncturing that thing with a needle: it's the microphone!
  19. Alec_t

    Post-soldering August ep 650 headphones, bluetooth mode doesn't turn on. Any hope?

    Is the 9th photo showing the Bluetooth module and its antenna? If so, how does power get to its two contact pads?
  20. Alec_t

    Electric Fence Charger

    Unless you unsolder and lift one leg of the cap, your measurement will be affected by any impedance in parallel with the cap. If you measure the isolated cap using an Ohms setting, you would expect a very brief low Ohms reading while the meter charges the cap. The resistance reading should then...
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