3 chips lost by single button press

Discussion in 'The Projects Forum' started by mah, Mar 7, 2014.

  1. mah

    Thread Starter Active Member

    Mar 15, 2010
    276
    2
    in the attached circuit i use analog signal to drive buck converter by atmega8 and it was working well . i connected MCP617 on the same breadboard to measure current in the circuit using zero ohm resistor . supply for atmega8 and the op amp from lm7805 where the input for lm7805 is 12 volt which was used as supply for IR2112 . when i add the op amp circuit i forgot to connect the negative terminal of the load to pin 3(+ve input) of the op amp then i switched on the power supply or the battery .i couldn't even see any signal the driver got very hot and the op amp ,but the atmega 8 didn't get hot but there was no output from it. i don't know what happened ,why did i lose the three ICs
     
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  2. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    Always measure output from voltage regulators before connecting.
    And use a LED, that will tell you abnormal voltages as well.

    If you are paranoid, use a zener diode 5.6V and a fuse. No seriously, it costs money and takes efforts to replace chips.
     
  3. mah

    Thread Starter Active Member

    Mar 15, 2010
    276
    2
    the output of regulator is 5 v and it can't exceed this value .i will lost my mind what is the reason that burnt those chips all of them and which one burn the others . please if any thing is n't clear you may ask
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,047
    Help me understand: The circuit above the red and green circled areas, everything other than the op-amp circuit, was working fine. You then added the op-amp circuit and did what?

    I also did not understand your reference to a "zero ohm resistor".
     
  5. mah

    Thread Starter Active Member

    Mar 15, 2010
    276
    2
    the driver got very hot and the op amp ,but the atmega 8 didn't get hot but there was no output from it.
    zero ohm resisitor (resistor in m ohm) .006 ohm
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,047
    I should have used a question mark:
    The circuit above the red and green circled areas, everything other than the op-amp circuit, was working fine?
    Please be precise about what was working, and then what you did that caused the problem. Reference your drawing. I still cannot follow your words.

    A photo of your build might also help. It is very easy to make wiring mistakes or to get a pinout wrong.
     
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