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  1. Alec_t

    How i can retrieve and change firmware?

    USB hub?
  2. Alec_t

    why open drain vs push pull?

    If you're turning the FET on only occasionally, the open drain plus pull-up resistor would be fine. It's when the FET requires high-speed switching that the push-pull driver comes into its own, to avoid the FET overheating as a result of it spending too long in the 'only-half-turned-on' state.
  3. Alec_t

    why open drain vs push pull?

    Open drain allows easy OR-ing of two driver signals if required, but needs a pull-up resistor. Push-pull provides a low impedance path to both rails.
  4. Alec_t

    Feedback loop for constant voltage amplifier. Simulated Aircraft Power.

    Does either the amp or the function generator have a designated gain/amplitude control input to accept a feedback signal? Are the amp and FG commercial units or home brew?
  5. Alec_t

    Components for small peristaltic pump

    That is the rated current when the motor is operating at full speed. At lower speeds the current will be more (it is at maximum when the motor is stalled or just starting up) because the back-emf generated by the motor is less. If you use PWM control, the motor will be drawing short bursts of...
  6. Alec_t

    How calculator Work

    Have a look at this.
  7. Alec_t

    Need Help With A Charging System On A Motorcycle. Have Schematic

    Looking at the post #1 pic, is the alternator 2-phase rather than 3-phase? I'm reading it this way :- The G wire goes to the field winding (shown in the external box), whose current is controlled by module 7 which is not only an ignition module but also a voltage regulator. There are 2 phase...
  8. Alec_t

    Output Voltage Selector

    If you haven't got room for those logic gates, perhaps use a BJT to clamp the 4V drive enabling signal, like this?
  9. Alec_t

    Where can I simulate "MAX1747"

    If no Spice model exists for that IC (I couldn't find one with a bit of googling) perhaps you could consult the datasheet and simulate the individual modules/functions within the IC, i.e. develop your own model.
  10. Alec_t

    Load control using PWM and temperature sensor

    You keep saying that +12V is connected to the drain. That is confusing, since it's not what the schematic shows. If you have indeed connected +12V to the drain, that would account for the FET frying. The +12V rail should be connected only to the diode cathode, to one terminal of the load, and to...
  11. Alec_t

    Oring of two Clocks

    Are both oscillators switching between 0V and 5V? How will you distinguish between an oscillator being in the 'logic 1' state and it being switched on? Is there some additional signal to indicate this? Welcome to EP!
  12. Alec_t

    Load control using PWM and temperature sensor

    +12V should not be connected directly to the FET drain. Do you have your load (lamp, LED with current-limiting resistor, other) connected in series between the drain terminal and +12V? Do you have the catching diode at the drain connected with the correct polarity (cathode at +12V)?
  13. Alec_t

    Output Voltage Selector

    Also, the OP wants to be able to select which source connects to the load, so an active switch is required.
  14. Alec_t

    Output Voltage Selector

    If all three FETs are on then current flow from the 6V supply back through the 4V supply will be excessive.
  15. Alec_t

    Load control using PWM and temperature sensor

    If Vcc=5V the 555 may be struggling to output 4V. With Vgs=4V that particular FET won't be turned on fully. You need either (a) a 'logic-level' rated FET or (b) Vcc increased to, say, 12V.
  16. Alec_t

    Problem with SD card

    Welcome to EP! If the card works fine elsewhere that suggests the problem is with the phone rather than the card itself. I'd return the phone if it's still under warranty. Have you tried a different card in the phone?
  17. Alec_t

    DC Motors and speed control

    To keep noise down I'd go for a brushless motor rather than a brushed one, and use belt drive rather than gear drive.
  18. Alec_t

    How is this Possible

    Have you actually measured 8VAC from the transformer secondary when the supply has no output load?
  19. Alec_t

    Help with powering immersion heater!!!

    If neutral wasn't connected to the element then it would not work. Please don't electrocute yourself. Working with unprotected connections like that is very dangerous.
  20. Alec_t

    Output Voltage Selector

    Oops! Well spotted. Forgot to flip the Spice symbol.
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