FET and diode question

Discussion in 'General Electronics Chat' started by ducttape, Nov 10, 2014.

  1. ducttape

    Thread Starter New Member

    Nov 10, 2014
    4
    0
    upload_2014-11-11_10-48-20.png

    Hi there,
    Can anyone help me to find the purpose of the diode in the circuit?

    Thank you
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,957
    1,097
  3. ducttape

    Thread Starter New Member

    Nov 10, 2014
    4
    0
  4. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    The led or general resistance load don't need the diode, because they won't generate
    the emf.
     
  5. ducttape

    Thread Starter New Member

    Nov 10, 2014
    4
    0
    Hi there, Thank you for your reply.
    Yes that was what I was thinking and the circuit is actually from the actual product schematic. I found that S1D diode is a rectifier. Could that diode be used for filtering purpose?
     
  6. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    What kinds of diode you want to use, that is considering about the frequency, as relay is a low speed active parts, so you can using a 1N4000~4007, it depends on the voltage of relay, I will choosing 1N4007 and I just buy that one, because I don't have to worry about which one is 1n4001 or some others when they mixed together.

    When you see a switching mode power supply then you have to using a flywheel diode even don't thinking and just use it.

    Go check the datasheets for very kinds of the EE parts is the best way to do.
     
  7. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,129
    266
    The diode is important if the load is ever disconnected, as it would be in many real world applications.
    If the load is disconnected, the drain is left floating, it's very easy for the drain to be exposed to voltages beyond the device ratings (static electricity, etc) and be destroyed, even with the power off.
    This diode clamps the drain to the positive supply rail, providing a safe path for over voltages, and of course inductive spikes too.
     
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,030
    3,799
    Is it a small signal diode, a rectifier diode OR, a Zener diode. Check the part number, find the datasheet and report back. A Zener diode limits the voltage - and would be cathode to Vcc as in your circuit.
     
  9. ducttape

    Thread Starter New Member

    Nov 10, 2014
    4
    0
    It's a rectifier dio
    de
     
Loading...