controlled switch

Discussion in 'General Electronics Chat' started by ROILEVI, Mar 11, 2009.

  1. ROILEVI

    Thread Starter New Member

    Mar 11, 2009
    3
    0
    1. i want to built a switch (on/off) circuit .
    to controll with DC. voltage of 5v (from microcontroller).
    controlled curent 4-10 A / 220-240 V ac.

    i assume with triac and moc
    but don't know how?

    2. if i will use a simple relay can i simply connect the relay to the
    microcontroller or do i need a buffer or something ??
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    If the micro-controller can source or sink the current needed by the relay, then no driver will be needed. The probability is you will need a MOSFET or Darlington to drive the relay.
     
  3. ROILEVI

    Thread Starter New Member

    Mar 11, 2009
    3
    0
    i have got a 8051 microcontroller.

    should i connect the relay directly to the output port?
    or maybe to the dac ?

    i'm afraid of current leakage form the relay or something that will
    burn the micro...
     
  4. gotumal

    Active Member

    Mar 24, 2008
    99
    0
    8051 is a generic series. What is a specific part no, so that we would know the sourse/sink capacity of pin. But as thingmaker3 said, you probably will need a transistor to drive the relay. Don't forget to put a free wheeling diode across relay (to protect transitor and probably a microcontroller).

    P.S. : You also need to be sure about the state of µc pin after resetting to avoide chattering of relay during power-up.

    All the best.
     
  5. ROILEVI

    Thread Starter New Member

    Mar 11, 2009
    3
    0
    can i use a moc (photo)"moc3041" and a triac (BTA12)??
     
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