irf630 alternative

Discussion in 'The Projects Forum' started by markosillypig, Oct 27, 2008.

  1. markosillypig

    Thread Starter Active Member

    Jul 21, 2008
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    hi all
    can any one tel me if there is an alternative to a irf630
    it only has to be about 60ma output
    thanks all :confused:
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    It's rated at 9A. What do you mean? Please post your circuit.

    John
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    An IRF630 is rated for 9A with Vdss of 200. What's your Vdss requirement?
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    Fro 60 mills, use a device in TO-92 like a 2N7000 (if 30 volts Vds if enough).
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Actually, a 2N7000 or 2N7002 will go to Vdss=60.
     
  6. markosillypig

    Thread Starter Active Member

    Jul 21, 2008
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    hi
    it is to drive 2 led's at 25ma here is the circuit it is the top one
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Yes, a 2N7000 will work for that. You will still need current limiting resistor(s).
     
  8. markosillypig

    Thread Starter Active Member

    Jul 21, 2008
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    are these on the circuit ?? if not where do the go
    thanks
    marko
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    The circuit does not have an LED so it doesn't show a current-limiting resistor for an LED.
    a current-limiting resistor must be in series with each LED.
     
  10. markosillypig

    Thread Starter Active Member

    Jul 21, 2008
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    hi
    can the 2n7000 replace an irfz42 as well??
     
  11. beenthere

    Retired Moderator

    Apr 20, 2004
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    That depends on the function. If it is switching no more than 60 volts at less than 250 ma, then yes.
     
  12. markosillypig

    Thread Starter Active Member

    Jul 21, 2008
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    hi all again
    this circuit works fine but i was just wondering what the r2 100k has to do with this circuit as i have removed it and it does not make a difference??
    and finaly i would like to increase the output voltage to the led would it be possible to do this via a 2n7000 from the vcc+ to the 2.7v output and then to the anode many thanks all
     
    Last edited: Oct 29, 2008
  13. SgtWookie

    Expert

    Jul 17, 2007
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    R2 ensures that the input is pulled to ground if there is nothing connected. This is in keeping with good design practice when using 4000 series CMOS IC's; you must never leave an input floating. In the absence of an input signal, R2 would pull the input to ground.
    The reason the voltage to the LED is so low is that 4000 series CMOS logic ICs have very low source/sink current capability.

    Connect: a suitable resistor to limit current through the LED to Vcc. To calculate this value:
    Rlimit >= (VoltageSource - VfLED) / DesiredLEDCurrent
    Example: if you are using a red LED that is rated for 1.7Vf @ 15mA, and VoltageSource = 5V, then:
    Rlimit = (5V - 1.7V) / 15mA = 3.3V / 0.015A = 220 Ohms, which is a standard value.
    Connect: the anode (long lead) of the LED to the other end of the resistor.
    Connect: the drain of the 2N7000 to the cathode (short lead) of the LED.
    Connect: the gate of the 2N7000 to pin 12 or 13 using a 100 Ohm resistor.
    Connect: the gate of the 2N7000 to the source using a 10k Ohm resistor. This ensures that the gate will be turned off if the IC is removed.
    Connect: the source of the 2N7000 to ground.
     
    Last edited: Oct 29, 2008
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