Inverse of Mosfet

Discussion in 'General Electronics Chat' started by Omais Ahmed, Aug 23, 2016.

  1. Omais Ahmed

    Thread Starter New Member

    Oct 4, 2015
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    Hello everyone,

    I need inverse of the attached circuit...means when I turn switch on led turns off as soon as switch off led turns on. LED should be on drain side as attached circuit shows. pls help me. circuit.png
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,501
    380
    hi,
    One option is just swapping R1 and the Switch over.?
    E
    We really need more information.
     
    Last edited: Aug 23, 2016
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  3. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    The silly answer is to put the switch across the LED so it shorts it out when the switch is on.

    Also, note that there is no current limiting (usually a resistor) for the LED, so unless the LED has it built-in, it will fail.

    To modify your circuit:
    1. eliminate R3 and connect Q1 emitter directly to GND
    2. connect R1 in series between Q1 base and B1 + terminal. This turns on Q1, Q2, and the LED all the time.
    3. connect the switch between Q1 base and GND. This turns off Q1 when the switch is closed.

    ak
     
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  4. Omais Ahmed

    Thread Starter New Member

    Oct 4, 2015
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    Thanks to both of you.

    I'm making ATS for generator when AC line will be disconnected then 12v battery supply turns on or vise versa...I dont want to use relay...I made ac to dc 5v circuit that will be connect to the below circuit as 5v signal.

    Both of you repled me I did the same that's working fine. but I need 5v switch when I apply 5 volt (ac to dc 5v) led turns off or 12v on low led turns on.

    also guide me please, I'm using arduino and driving solenoid and Ignition by mosfet taking 5v from arduino and switch 12v using mosfet. Is it safe?

    Thanks
     
  5. ci139

    Member

    Jul 11, 2016
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  6. Omais Ahmed

    Thread Starter New Member

    Oct 4, 2015
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  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    The SSR referenced in post#5 is called a "relay" but it is solid state, meaning it uses mosfets to do the job. It doesn't have contact points and a coil. Basically does what your asking in a ready made circuit that is a sealed module.
     
  8. Omais Ahmed

    Thread Starter New Member

    Oct 4, 2015
    7
    0
    For ac to dc conversion or isolation?
     
  9. shortbus

    AAC Fanatic!

    Sep 30, 2009
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