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  1. Alec_t

    Limit car battery current

    So which project requires 41A?
  2. Alec_t

    Automatic Triggering of a Water Pump with 12 volts followed by 7 volts operating voltage

    Here's another option, using a 555 to generate a PWM signal whose duty cycle drops over a ~1 sec period after power-up. This signal switches a MOSFET to control the pump motor, dropping its effective supply voltage from 12V to ~7V (adjustable with the pot) over that period. The advantage of...
  3. Alec_t

    Convert PWM output to variable frequency

    You could perhaps use something based on this sim, where V2 is a control voltage derivable by integrating the PWM signal :-
  4. Alec_t

    Automatic Triggering of a Water Pump with 12 volts followed by 7 volts operating voltage

    Assuming two of the pump pins are for 12V and ground, what is the third pin for if not for PWM?
  5. Alec_t

    AC generator

    Use the 'Upload a file' button to post the picture.
  6. Alec_t

    Beep once Circuit

    Try these changes: R1=10k C1=220u Forward biased diode across R2 (100k).
  7. Alec_t

    detecting shaft rotation

    You could put a paint mark on the shaft end and detect it optically.
  8. Alec_t

    Recharging water batteries

    What voltage does your 'alt water' battery (whatever that is) generate?
  9. Alec_t

    Simple inverter circuit

    What are the input and output voltage and current requirements?
  10. Alec_t

    DC current pulsator

    Welcome to EP! Have a google for "555 timer relay". Several schematics pop up.
  11. Alec_t

    Volts to ohms for fuel sender

    I suspect vehicle vibration would cause havoc with that. There might be safety issues too, with fuel tanks flopping around on hinges or springs or whatever.
  12. Alec_t

    audio amplifier

    Googling "AN214" gives a couple of circuits. Looks like the SF214 is a related IC.
  13. Alec_t

    Problem: Schmitt Trigger not giving ON/OFF output

    Should be fine (albeit expensive). As for offset-nulling on the 741, read the guidance in its datasheet. Some authors on some websites don't bother checking the datasheets :).
  14. Alec_t

    Underwater Wireless Communication

    Simply try it and see. Put a cell-phone in a watertight box, submerge it, then call it from another phone. Water salinity may be a major factor here.
  15. Alec_t

    Need Help finding inductance in a RL circuit

    There are two possible configurations of R and L within your 'RL Filter' module, so there are two possible answers to your question. This simulation demonstrates that a single inductance value would give two different results depending on the configuration.
  16. Alec_t

    Need Help finding inductance in a RL circuit

    Welcome to EP! We're missing a schematic. Where is the output taken from?
  17. Alec_t

    Volts to ohms for fuel sender

    Another option might be a circuit based on a LM3914.
  18. Alec_t

    AC/DC converter - If I cut/ splice the wire can I use it in my car?

    Yes, the brick provides 12VDC for the radio. Yes, you can cut/splice as you suggest; but be sure to note which wire goes to the connector centre pin (+ve) so that the polarity is correct. However, you might want to consider using a small box to house additional components for suppressing...
  19. Alec_t

    Volts to ohms for fuel sender

    Does your 90 Ohms correspond to full or to empty? What voltage does your instrument cluster run on?
  20. Alec_t

    Microwave inverter project

    That's definitely a high frequency (many kHz) transformer so definitely can't be connected directly to mains (50/60Hz).
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