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Circuit to drive a fuel injectors with NE555

Discussion in 'Automotive Electronics' started by milkoni, Feb 8, 2017.

  1. milkoni

    milkoni Member

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    Hi all,
    I have a question about my circuit. Which position is better to switch On/Off the injector?
    Or to build a driving circuit with NE555 for each injector?
    I'm attaching an image to illustrate.
    Thanks in advance!

    P.S.
    I've decided to use the signal after two transistors gate to MOSFET's gate, to switch injector On and Off. I've tested this on experimental board - it works fine I think.
     

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    Last edited: Mar 16, 2017
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    That could leave Q1 drawing excessive current. Why not simply disconnect the 12V supply, so as to eliminate any standby current?
     
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  3. milkoni

    milkoni Member

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    I agree Alec. I've changed the circuit.
    Thank you!
     

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  4. dave

    Dave New Member

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  5. shokjok

    shokjok Member

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    The circuit may burn the injectors open when you apply twelve volts this way. The internal MOSFET resistance can be supplemented with a resistor to reduce the injector feed voltage.
     
  6. shokjok

    shokjok Member

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    spec, capacitor C3 ( 220n) should be connected across 555 pins 1 and 8, not to pin 7 as shown, referencing your comment #4 in thread #4.
     

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