Problem with switching transistor

Discussion in 'The Projects Forum' started by ecka333, Nov 9, 2009.

  1. ecka333

    Thread Starter Active Member

    Oct 1, 2009
    76
    0
    I have made power regulator with pic16f84a. Everything works fine, while microcontroller DD1 supplies current to transistor VT1 base: VT2 is switching circuit VT2-Rap-VD1_VD4. Rap is load, in my case 100W incandescent lamp. If i remove PIC 16F84A supply (5 volts), but leave 220V supply to load, VT2 blows out in a moment and base-emiter junction becomes 0 ohms. Maybe there is a problem i VT1 and VT2 connection? Any ideas?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Your circuit is a lethal shock hazard. You remove the protection of the step down transformer by strapping the 5 volt ground to the AC line.

    VT2 should be a triac, and be triggered by an optoisolator. It's simply too dangerous to use as it is.
     
  3. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Wow, that is certainly scary! :eek::eek:
     
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